![Peter Zijlstra](/assets/img/avatar_default.png)
[ Upstream commit5e351ad106
] We can't invalidate xhlocks when we've not yet allocated any. Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Fixes:f52be57080
("locking/lockdep: Untangle xhlock history save/restore from task independence") Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
5151 lines
126 KiB
C
5151 lines
126 KiB
C
/*
|
|
* kernel/lockdep.c
|
|
*
|
|
* Runtime locking correctness validator
|
|
*
|
|
* Started by Ingo Molnar:
|
|
*
|
|
* Copyright (C) 2006,2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
|
|
* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
|
|
*
|
|
* this code maps all the lock dependencies as they occur in a live kernel
|
|
* and will warn about the following classes of locking bugs:
|
|
*
|
|
* - lock inversion scenarios
|
|
* - circular lock dependencies
|
|
* - hardirq/softirq safe/unsafe locking bugs
|
|
*
|
|
* Bugs are reported even if the current locking scenario does not cause
|
|
* any deadlock at this point.
|
|
*
|
|
* I.e. if anytime in the past two locks were taken in a different order,
|
|
* even if it happened for another task, even if those were different
|
|
* locks (but of the same class as this lock), this code will detect it.
|
|
*
|
|
* Thanks to Arjan van de Ven for coming up with the initial idea of
|
|
* mapping lock dependencies runtime.
|
|
*/
|
|
#define DISABLE_BRANCH_PROFILING
|
|
#include <linux/mutex.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/sched/clock.h>
|
|
#include <linux/sched/task.h>
|
|
#include <linux/sched/mm.h>
|
|
#include <linux/delay.h>
|
|
#include <linux/module.h>
|
|
#include <linux/proc_fs.h>
|
|
#include <linux/seq_file.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/kallsyms.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/stacktrace.h>
|
|
#include <linux/debug_locks.h>
|
|
#include <linux/irqflags.h>
|
|
#include <linux/utsname.h>
|
|
#include <linux/hash.h>
|
|
#include <linux/ftrace.h>
|
|
#include <linux/stringify.h>
|
|
#include <linux/bitops.h>
|
|
#include <linux/gfp.h>
|
|
#include <linux/random.h>
|
|
#include <linux/jhash.h>
|
|
|
|
#include <asm/sections.h>
|
|
|
|
#include "lockdep_internals.h"
|
|
|
|
#define CREATE_TRACE_POINTS
|
|
#include <trace/events/lock.h>
|
|
|
|
#ifdef CONFIG_LOCKDEP_CROSSRELEASE
|
|
#include <linux/slab.h>
|
|
#endif
|
|
|
|
#ifdef CONFIG_PROVE_LOCKING
|
|
int prove_locking = 1;
|
|
module_param(prove_locking, int, 0644);
|
|
#else
|
|
#define prove_locking 0
|
|
#endif
|
|
|
|
#ifdef CONFIG_LOCK_STAT
|
|
int lock_stat = 1;
|
|
module_param(lock_stat, int, 0644);
|
|
#else
|
|
#define lock_stat 0
|
|
#endif
|
|
|
|
/*
|
|
* lockdep_lock: protects the lockdep graph, the hashes and the
|
|
* class/list/hash allocators.
|
|
*
|
|
* This is one of the rare exceptions where it's justified
|
|
* to use a raw spinlock - we really dont want the spinlock
|
|
* code to recurse back into the lockdep code...
|
|
*/
|
|
static arch_spinlock_t lockdep_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
|
|
|
|
static int graph_lock(void)
|
|
{
|
|
arch_spin_lock(&lockdep_lock);
|
|
/*
|
|
* Make sure that if another CPU detected a bug while
|
|
* walking the graph we dont change it (while the other
|
|
* CPU is busy printing out stuff with the graph lock
|
|
* dropped already)
|
|
*/
|
|
if (!debug_locks) {
|
|
arch_spin_unlock(&lockdep_lock);
|
|
return 0;
|
|
}
|
|
/* prevent any recursions within lockdep from causing deadlocks */
|
|
current->lockdep_recursion++;
|
|
return 1;
|
|
}
|
|
|
|
static inline int graph_unlock(void)
|
|
{
|
|
if (debug_locks && !arch_spin_is_locked(&lockdep_lock)) {
|
|
/*
|
|
* The lockdep graph lock isn't locked while we expect it to
|
|
* be, we're confused now, bye!
|
|
*/
|
|
return DEBUG_LOCKS_WARN_ON(1);
|
|
}
|
|
|
|
current->lockdep_recursion--;
|
|
arch_spin_unlock(&lockdep_lock);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Turn lock debugging off and return with 0 if it was off already,
|
|
* and also release the graph lock:
|
|
*/
|
|
static inline int debug_locks_off_graph_unlock(void)
|
|
{
|
|
int ret = debug_locks_off();
|
|
|
|
arch_spin_unlock(&lockdep_lock);
|
|
|
|
return ret;
|
|
}
|
|
|
|
unsigned long nr_list_entries;
|
|
static struct lock_list list_entries[MAX_LOCKDEP_ENTRIES];
|
|
|
|
/*
|
|
* All data structures here are protected by the global debug_lock.
|
|
*
|
|
* Mutex key structs only get allocated, once during bootup, and never
|
|
* get freed - this significantly simplifies the debugging code.
|
|
*/
|
|
unsigned long nr_lock_classes;
|
|
static struct lock_class lock_classes[MAX_LOCKDEP_KEYS];
|
|
|
|
static inline struct lock_class *hlock_class(struct held_lock *hlock)
|
|
{
|
|
if (!hlock->class_idx) {
|
|
/*
|
|
* Someone passed in garbage, we give up.
|
|
*/
|
|
DEBUG_LOCKS_WARN_ON(1);
|
|
return NULL;
|
|
}
|
|
return lock_classes + hlock->class_idx - 1;
|
|
}
|
|
|
|
#ifdef CONFIG_LOCK_STAT
|
|
static DEFINE_PER_CPU(struct lock_class_stats[MAX_LOCKDEP_KEYS], cpu_lock_stats);
|
|
|
|
static inline u64 lockstat_clock(void)
|
|
{
|
|
return local_clock();
|
|
}
|
|
|
|
static int lock_point(unsigned long points[], unsigned long ip)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < LOCKSTAT_POINTS; i++) {
|
|
if (points[i] == 0) {
|
|
points[i] = ip;
|
|
break;
|
|
}
|
|
if (points[i] == ip)
|
|
break;
|
|
}
|
|
|
|
return i;
|
|
}
|
|
|
|
static void lock_time_inc(struct lock_time *lt, u64 time)
|
|
{
|
|
if (time > lt->max)
|
|
lt->max = time;
|
|
|
|
if (time < lt->min || !lt->nr)
|
|
lt->min = time;
|
|
|
|
lt->total += time;
|
|
lt->nr++;
|
|
}
|
|
|
|
static inline void lock_time_add(struct lock_time *src, struct lock_time *dst)
|
|
{
|
|
if (!src->nr)
|
|
return;
|
|
|
|
if (src->max > dst->max)
|
|
dst->max = src->max;
|
|
|
|
if (src->min < dst->min || !dst->nr)
|
|
dst->min = src->min;
|
|
|
|
dst->total += src->total;
|
|
dst->nr += src->nr;
|
|
}
|
|
|
|
struct lock_class_stats lock_stats(struct lock_class *class)
|
|
{
|
|
struct lock_class_stats stats;
|
|
int cpu, i;
|
|
|
|
memset(&stats, 0, sizeof(struct lock_class_stats));
|
|
for_each_possible_cpu(cpu) {
|
|
struct lock_class_stats *pcs =
|
|
&per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
|
|
|
|
for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
|
|
stats.contention_point[i] += pcs->contention_point[i];
|
|
|
|
for (i = 0; i < ARRAY_SIZE(stats.contending_point); i++)
|
|
stats.contending_point[i] += pcs->contending_point[i];
|
|
|
|
lock_time_add(&pcs->read_waittime, &stats.read_waittime);
|
|
lock_time_add(&pcs->write_waittime, &stats.write_waittime);
|
|
|
|
lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
|
|
lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
|
|
|
|
for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
|
|
stats.bounces[i] += pcs->bounces[i];
|
|
}
|
|
|
|
return stats;
|
|
}
|
|
|
|
void clear_lock_stats(struct lock_class *class)
|
|
{
|
|
int cpu;
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
struct lock_class_stats *cpu_stats =
|
|
&per_cpu(cpu_lock_stats, cpu)[class - lock_classes];
|
|
|
|
memset(cpu_stats, 0, sizeof(struct lock_class_stats));
|
|
}
|
|
memset(class->contention_point, 0, sizeof(class->contention_point));
|
|
memset(class->contending_point, 0, sizeof(class->contending_point));
|
|
}
|
|
|
|
static struct lock_class_stats *get_lock_stats(struct lock_class *class)
|
|
{
|
|
return &get_cpu_var(cpu_lock_stats)[class - lock_classes];
|
|
}
|
|
|
|
static void put_lock_stats(struct lock_class_stats *stats)
|
|
{
|
|
put_cpu_var(cpu_lock_stats);
|
|
}
|
|
|
|
static void lock_release_holdtime(struct held_lock *hlock)
|
|
{
|
|
struct lock_class_stats *stats;
|
|
u64 holdtime;
|
|
|
|
if (!lock_stat)
|
|
return;
|
|
|
|
holdtime = lockstat_clock() - hlock->holdtime_stamp;
|
|
|
|
stats = get_lock_stats(hlock_class(hlock));
|
|
if (hlock->read)
|
|
lock_time_inc(&stats->read_holdtime, holdtime);
|
|
else
|
|
lock_time_inc(&stats->write_holdtime, holdtime);
|
|
put_lock_stats(stats);
|
|
}
|
|
#else
|
|
static inline void lock_release_holdtime(struct held_lock *hlock)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* We keep a global list of all lock classes. The list only grows,
|
|
* never shrinks. The list is only accessed with the lockdep
|
|
* spinlock lock held.
|
|
*/
|
|
LIST_HEAD(all_lock_classes);
|
|
|
|
/*
|
|
* The lockdep classes are in a hash-table as well, for fast lookup:
|
|
*/
|
|
#define CLASSHASH_BITS (MAX_LOCKDEP_KEYS_BITS - 1)
|
|
#define CLASSHASH_SIZE (1UL << CLASSHASH_BITS)
|
|
#define __classhashfn(key) hash_long((unsigned long)key, CLASSHASH_BITS)
|
|
#define classhashentry(key) (classhash_table + __classhashfn((key)))
|
|
|
|
static struct hlist_head classhash_table[CLASSHASH_SIZE];
|
|
|
|
/*
|
|
* We put the lock dependency chains into a hash-table as well, to cache
|
|
* their existence:
|
|
*/
|
|
#define CHAINHASH_BITS (MAX_LOCKDEP_CHAINS_BITS-1)
|
|
#define CHAINHASH_SIZE (1UL << CHAINHASH_BITS)
|
|
#define __chainhashfn(chain) hash_long(chain, CHAINHASH_BITS)
|
|
#define chainhashentry(chain) (chainhash_table + __chainhashfn((chain)))
|
|
|
|
static struct hlist_head chainhash_table[CHAINHASH_SIZE];
|
|
|
|
/*
|
|
* The hash key of the lock dependency chains is a hash itself too:
|
|
* it's a hash of all locks taken up to that lock, including that lock.
|
|
* It's a 64-bit hash, because it's important for the keys to be
|
|
* unique.
|
|
*/
|
|
static inline u64 iterate_chain_key(u64 key, u32 idx)
|
|
{
|
|
u32 k0 = key, k1 = key >> 32;
|
|
|
|
__jhash_mix(idx, k0, k1); /* Macro that modifies arguments! */
|
|
|
|
return k0 | (u64)k1 << 32;
|
|
}
|
|
|
|
void lockdep_off(void)
|
|
{
|
|
current->lockdep_recursion++;
|
|
}
|
|
EXPORT_SYMBOL(lockdep_off);
|
|
|
|
void lockdep_on(void)
|
|
{
|
|
current->lockdep_recursion--;
|
|
}
|
|
EXPORT_SYMBOL(lockdep_on);
|
|
|
|
/*
|
|
* Debugging switches:
|
|
*/
|
|
|
|
#define VERBOSE 0
|
|
#define VERY_VERBOSE 0
|
|
|
|
#if VERBOSE
|
|
# define HARDIRQ_VERBOSE 1
|
|
# define SOFTIRQ_VERBOSE 1
|
|
#else
|
|
# define HARDIRQ_VERBOSE 0
|
|
# define SOFTIRQ_VERBOSE 0
|
|
#endif
|
|
|
|
#if VERBOSE || HARDIRQ_VERBOSE || SOFTIRQ_VERBOSE
|
|
/*
|
|
* Quick filtering for interesting events:
|
|
*/
|
|
static int class_filter(struct lock_class *class)
|
|
{
|
|
#if 0
|
|
/* Example */
|
|
if (class->name_version == 1 &&
|
|
!strcmp(class->name, "lockname"))
|
|
return 1;
|
|
if (class->name_version == 1 &&
|
|
!strcmp(class->name, "&struct->lockfield"))
|
|
return 1;
|
|
#endif
|
|
/* Filter everything else. 1 would be to allow everything else */
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
static int verbose(struct lock_class *class)
|
|
{
|
|
#if VERBOSE
|
|
return class_filter(class);
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Stack-trace: tightly packed array of stack backtrace
|
|
* addresses. Protected by the graph_lock.
|
|
*/
|
|
unsigned long nr_stack_trace_entries;
|
|
static unsigned long stack_trace[MAX_STACK_TRACE_ENTRIES];
|
|
|
|
static void print_lockdep_off(const char *bug_msg)
|
|
{
|
|
printk(KERN_DEBUG "%s\n", bug_msg);
|
|
printk(KERN_DEBUG "turning off the locking correctness validator.\n");
|
|
#ifdef CONFIG_LOCK_STAT
|
|
printk(KERN_DEBUG "Please attach the output of /proc/lock_stat to the bug report\n");
|
|
#endif
|
|
}
|
|
|
|
static int save_trace(struct stack_trace *trace)
|
|
{
|
|
trace->nr_entries = 0;
|
|
trace->max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
|
|
trace->entries = stack_trace + nr_stack_trace_entries;
|
|
|
|
trace->skip = 3;
|
|
|
|
save_stack_trace(trace);
|
|
|
|
/*
|
|
* Some daft arches put -1 at the end to indicate its a full trace.
|
|
*
|
|
* <rant> this is buggy anyway, since it takes a whole extra entry so a
|
|
* complete trace that maxes out the entries provided will be reported
|
|
* as incomplete, friggin useless </rant>
|
|
*/
|
|
if (trace->nr_entries != 0 &&
|
|
trace->entries[trace->nr_entries-1] == ULONG_MAX)
|
|
trace->nr_entries--;
|
|
|
|
trace->max_entries = trace->nr_entries;
|
|
|
|
nr_stack_trace_entries += trace->nr_entries;
|
|
|
|
if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
|
|
if (!debug_locks_off_graph_unlock())
|
|
return 0;
|
|
|
|
print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
unsigned int nr_hardirq_chains;
|
|
unsigned int nr_softirq_chains;
|
|
unsigned int nr_process_chains;
|
|
unsigned int max_lockdep_depth;
|
|
|
|
#ifdef CONFIG_DEBUG_LOCKDEP
|
|
/*
|
|
* Various lockdep statistics:
|
|
*/
|
|
DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
|
|
#endif
|
|
|
|
/*
|
|
* Locking printouts:
|
|
*/
|
|
|
|
#define __USAGE(__STATE) \
|
|
[LOCK_USED_IN_##__STATE] = "IN-"__stringify(__STATE)"-W", \
|
|
[LOCK_ENABLED_##__STATE] = __stringify(__STATE)"-ON-W", \
|
|
[LOCK_USED_IN_##__STATE##_READ] = "IN-"__stringify(__STATE)"-R",\
|
|
[LOCK_ENABLED_##__STATE##_READ] = __stringify(__STATE)"-ON-R",
|
|
|
|
static const char *usage_str[] =
|
|
{
|
|
#define LOCKDEP_STATE(__STATE) __USAGE(__STATE)
|
|
#include "lockdep_states.h"
|
|
#undef LOCKDEP_STATE
|
|
[LOCK_USED] = "INITIAL USE",
|
|
};
|
|
|
|
const char * __get_key_name(struct lockdep_subclass_key *key, char *str)
|
|
{
|
|
return kallsyms_lookup((unsigned long)key, NULL, NULL, NULL, str);
|
|
}
|
|
|
|
static inline unsigned long lock_flag(enum lock_usage_bit bit)
|
|
{
|
|
return 1UL << bit;
|
|
}
|
|
|
|
static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
|
|
{
|
|
char c = '.';
|
|
|
|
if (class->usage_mask & lock_flag(bit + 2))
|
|
c = '+';
|
|
if (class->usage_mask & lock_flag(bit)) {
|
|
c = '-';
|
|
if (class->usage_mask & lock_flag(bit + 2))
|
|
c = '?';
|
|
}
|
|
|
|
return c;
|
|
}
|
|
|
|
void get_usage_chars(struct lock_class *class, char usage[LOCK_USAGE_CHARS])
|
|
{
|
|
int i = 0;
|
|
|
|
#define LOCKDEP_STATE(__STATE) \
|
|
usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE); \
|
|
usage[i++] = get_usage_char(class, LOCK_USED_IN_##__STATE##_READ);
|
|
#include "lockdep_states.h"
|
|
#undef LOCKDEP_STATE
|
|
|
|
usage[i] = '\0';
|
|
}
|
|
|
|
static void __print_lock_name(struct lock_class *class)
|
|
{
|
|
char str[KSYM_NAME_LEN];
|
|
const char *name;
|
|
|
|
name = class->name;
|
|
if (!name) {
|
|
name = __get_key_name(class->key, str);
|
|
printk(KERN_CONT "%s", name);
|
|
} else {
|
|
printk(KERN_CONT "%s", name);
|
|
if (class->name_version > 1)
|
|
printk(KERN_CONT "#%d", class->name_version);
|
|
if (class->subclass)
|
|
printk(KERN_CONT "/%d", class->subclass);
|
|
}
|
|
}
|
|
|
|
static void print_lock_name(struct lock_class *class)
|
|
{
|
|
char usage[LOCK_USAGE_CHARS];
|
|
|
|
get_usage_chars(class, usage);
|
|
|
|
printk(KERN_CONT " (");
|
|
__print_lock_name(class);
|
|
printk(KERN_CONT "){%s}", usage);
|
|
}
|
|
|
|
static void print_lockdep_cache(struct lockdep_map *lock)
|
|
{
|
|
const char *name;
|
|
char str[KSYM_NAME_LEN];
|
|
|
|
name = lock->name;
|
|
if (!name)
|
|
name = __get_key_name(lock->key->subkeys, str);
|
|
|
|
printk(KERN_CONT "%s", name);
|
|
}
|
|
|
|
static void print_lock(struct held_lock *hlock)
|
|
{
|
|
/*
|
|
* We can be called locklessly through debug_show_all_locks() so be
|
|
* extra careful, the hlock might have been released and cleared.
|
|
*/
|
|
unsigned int class_idx = hlock->class_idx;
|
|
|
|
/* Don't re-read hlock->class_idx, can't use READ_ONCE() on bitfields: */
|
|
barrier();
|
|
|
|
if (!class_idx || (class_idx - 1) >= MAX_LOCKDEP_KEYS) {
|
|
printk(KERN_CONT "<RELEASED>\n");
|
|
return;
|
|
}
|
|
|
|
print_lock_name(lock_classes + class_idx - 1);
|
|
printk(KERN_CONT ", at: [<%p>] %pS\n",
|
|
(void *)hlock->acquire_ip, (void *)hlock->acquire_ip);
|
|
}
|
|
|
|
static void lockdep_print_held_locks(struct task_struct *curr)
|
|
{
|
|
int i, depth = curr->lockdep_depth;
|
|
|
|
if (!depth) {
|
|
printk("no locks held by %s/%d.\n", curr->comm, task_pid_nr(curr));
|
|
return;
|
|
}
|
|
printk("%d lock%s held by %s/%d:\n",
|
|
depth, depth > 1 ? "s" : "", curr->comm, task_pid_nr(curr));
|
|
|
|
for (i = 0; i < depth; i++) {
|
|
printk(" #%d: ", i);
|
|
print_lock(curr->held_locks + i);
|
|
}
|
|
}
|
|
|
|
static void print_kernel_ident(void)
|
|
{
|
|
printk("%s %.*s %s\n", init_utsname()->release,
|
|
(int)strcspn(init_utsname()->version, " "),
|
|
init_utsname()->version,
|
|
print_tainted());
|
|
}
|
|
|
|
static int very_verbose(struct lock_class *class)
|
|
{
|
|
#if VERY_VERBOSE
|
|
return class_filter(class);
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Is this the address of a static object:
|
|
*/
|
|
#ifdef __KERNEL__
|
|
static int static_obj(void *obj)
|
|
{
|
|
unsigned long start = (unsigned long) &_stext,
|
|
end = (unsigned long) &_end,
|
|
addr = (unsigned long) obj;
|
|
|
|
/*
|
|
* static variable?
|
|
*/
|
|
if ((addr >= start) && (addr < end))
|
|
return 1;
|
|
|
|
if (arch_is_kernel_data(addr))
|
|
return 1;
|
|
|
|
/*
|
|
* in-kernel percpu var?
|
|
*/
|
|
if (is_kernel_percpu_address(addr))
|
|
return 1;
|
|
|
|
/*
|
|
* module static or percpu var?
|
|
*/
|
|
return is_module_address(addr) || is_module_percpu_address(addr);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* To make lock name printouts unique, we calculate a unique
|
|
* class->name_version generation counter:
|
|
*/
|
|
static int count_matching_names(struct lock_class *new_class)
|
|
{
|
|
struct lock_class *class;
|
|
int count = 0;
|
|
|
|
if (!new_class->name)
|
|
return 0;
|
|
|
|
list_for_each_entry_rcu(class, &all_lock_classes, lock_entry) {
|
|
if (new_class->key - new_class->subclass == class->key)
|
|
return class->name_version;
|
|
if (class->name && !strcmp(class->name, new_class->name))
|
|
count = max(count, class->name_version);
|
|
}
|
|
|
|
return count + 1;
|
|
}
|
|
|
|
/*
|
|
* Register a lock's class in the hash-table, if the class is not present
|
|
* yet. Otherwise we look it up. We cache the result in the lock object
|
|
* itself, so actual lookup of the hash should be once per lock object.
|
|
*/
|
|
static inline struct lock_class *
|
|
look_up_lock_class(struct lockdep_map *lock, unsigned int subclass)
|
|
{
|
|
struct lockdep_subclass_key *key;
|
|
struct hlist_head *hash_head;
|
|
struct lock_class *class;
|
|
bool is_static = false;
|
|
|
|
if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {
|
|
debug_locks_off();
|
|
printk(KERN_ERR
|
|
"BUG: looking up invalid subclass: %u\n", subclass);
|
|
printk(KERN_ERR
|
|
"turning off the locking correctness validator.\n");
|
|
dump_stack();
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* Static locks do not have their class-keys yet - for them the key
|
|
* is the lock object itself. If the lock is in the per cpu area,
|
|
* the canonical address of the lock (per cpu offset removed) is
|
|
* used.
|
|
*/
|
|
if (unlikely(!lock->key)) {
|
|
unsigned long can_addr, addr = (unsigned long)lock;
|
|
|
|
if (__is_kernel_percpu_address(addr, &can_addr))
|
|
lock->key = (void *)can_addr;
|
|
else if (__is_module_percpu_address(addr, &can_addr))
|
|
lock->key = (void *)can_addr;
|
|
else if (static_obj(lock))
|
|
lock->key = (void *)lock;
|
|
else
|
|
return ERR_PTR(-EINVAL);
|
|
is_static = true;
|
|
}
|
|
|
|
/*
|
|
* NOTE: the class-key must be unique. For dynamic locks, a static
|
|
* lock_class_key variable is passed in through the mutex_init()
|
|
* (or spin_lock_init()) call - which acts as the key. For static
|
|
* locks we use the lock object itself as the key.
|
|
*/
|
|
BUILD_BUG_ON(sizeof(struct lock_class_key) >
|
|
sizeof(struct lockdep_map));
|
|
|
|
key = lock->key->subkeys + subclass;
|
|
|
|
hash_head = classhashentry(key);
|
|
|
|
/*
|
|
* We do an RCU walk of the hash, see lockdep_free_key_range().
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return NULL;
|
|
|
|
hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
|
|
if (class->key == key) {
|
|
/*
|
|
* Huh! same key, different name? Did someone trample
|
|
* on some memory? We're most confused.
|
|
*/
|
|
WARN_ON_ONCE(class->name != lock->name);
|
|
return class;
|
|
}
|
|
}
|
|
|
|
return is_static || static_obj(lock->key) ? NULL : ERR_PTR(-EINVAL);
|
|
}
|
|
|
|
#ifdef CONFIG_LOCKDEP_CROSSRELEASE
|
|
static void cross_init(struct lockdep_map *lock, int cross);
|
|
static int cross_lock(struct lockdep_map *lock);
|
|
static int lock_acquire_crosslock(struct held_lock *hlock);
|
|
static int lock_release_crosslock(struct lockdep_map *lock);
|
|
#else
|
|
static inline void cross_init(struct lockdep_map *lock, int cross) {}
|
|
static inline int cross_lock(struct lockdep_map *lock) { return 0; }
|
|
static inline int lock_acquire_crosslock(struct held_lock *hlock) { return 2; }
|
|
static inline int lock_release_crosslock(struct lockdep_map *lock) { return 2; }
|
|
#endif
|
|
|
|
/*
|
|
* Register a lock's class in the hash-table, if the class is not present
|
|
* yet. Otherwise we look it up. We cache the result in the lock object
|
|
* itself, so actual lookup of the hash should be once per lock object.
|
|
*/
|
|
static struct lock_class *
|
|
register_lock_class(struct lockdep_map *lock, unsigned int subclass, int force)
|
|
{
|
|
struct lockdep_subclass_key *key;
|
|
struct hlist_head *hash_head;
|
|
struct lock_class *class;
|
|
|
|
DEBUG_LOCKS_WARN_ON(!irqs_disabled());
|
|
|
|
class = look_up_lock_class(lock, subclass);
|
|
if (likely(!IS_ERR_OR_NULL(class)))
|
|
goto out_set_class_cache;
|
|
|
|
/*
|
|
* Debug-check: all keys must be persistent!
|
|
*/
|
|
if (IS_ERR(class)) {
|
|
debug_locks_off();
|
|
printk("INFO: trying to register non-static key.\n");
|
|
printk("the code is fine but needs lockdep annotation.\n");
|
|
printk("turning off the locking correctness validator.\n");
|
|
dump_stack();
|
|
return NULL;
|
|
}
|
|
|
|
key = lock->key->subkeys + subclass;
|
|
hash_head = classhashentry(key);
|
|
|
|
if (!graph_lock()) {
|
|
return NULL;
|
|
}
|
|
/*
|
|
* We have to do the hash-walk again, to avoid races
|
|
* with another CPU:
|
|
*/
|
|
hlist_for_each_entry_rcu(class, hash_head, hash_entry) {
|
|
if (class->key == key)
|
|
goto out_unlock_set;
|
|
}
|
|
|
|
/*
|
|
* Allocate a new key from the static array, and add it to
|
|
* the hash:
|
|
*/
|
|
if (nr_lock_classes >= MAX_LOCKDEP_KEYS) {
|
|
if (!debug_locks_off_graph_unlock()) {
|
|
return NULL;
|
|
}
|
|
|
|
print_lockdep_off("BUG: MAX_LOCKDEP_KEYS too low!");
|
|
dump_stack();
|
|
return NULL;
|
|
}
|
|
class = lock_classes + nr_lock_classes++;
|
|
debug_atomic_inc(nr_unused_locks);
|
|
class->key = key;
|
|
class->name = lock->name;
|
|
class->subclass = subclass;
|
|
INIT_LIST_HEAD(&class->lock_entry);
|
|
INIT_LIST_HEAD(&class->locks_before);
|
|
INIT_LIST_HEAD(&class->locks_after);
|
|
class->name_version = count_matching_names(class);
|
|
/*
|
|
* We use RCU's safe list-add method to make
|
|
* parallel walking of the hash-list safe:
|
|
*/
|
|
hlist_add_head_rcu(&class->hash_entry, hash_head);
|
|
/*
|
|
* Add it to the global list of classes:
|
|
*/
|
|
list_add_tail_rcu(&class->lock_entry, &all_lock_classes);
|
|
|
|
if (verbose(class)) {
|
|
graph_unlock();
|
|
|
|
printk("\nnew class %p: %s", class->key, class->name);
|
|
if (class->name_version > 1)
|
|
printk(KERN_CONT "#%d", class->name_version);
|
|
printk(KERN_CONT "\n");
|
|
dump_stack();
|
|
|
|
if (!graph_lock()) {
|
|
return NULL;
|
|
}
|
|
}
|
|
out_unlock_set:
|
|
graph_unlock();
|
|
|
|
out_set_class_cache:
|
|
if (!subclass || force)
|
|
lock->class_cache[0] = class;
|
|
else if (subclass < NR_LOCKDEP_CACHING_CLASSES)
|
|
lock->class_cache[subclass] = class;
|
|
|
|
/*
|
|
* Hash collision, did we smoke some? We found a class with a matching
|
|
* hash but the subclass -- which is hashed in -- didn't match.
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(class->subclass != subclass))
|
|
return NULL;
|
|
|
|
return class;
|
|
}
|
|
|
|
#ifdef CONFIG_PROVE_LOCKING
|
|
/*
|
|
* Allocate a lockdep entry. (assumes the graph_lock held, returns
|
|
* with NULL on failure)
|
|
*/
|
|
static struct lock_list *alloc_list_entry(void)
|
|
{
|
|
if (nr_list_entries >= MAX_LOCKDEP_ENTRIES) {
|
|
if (!debug_locks_off_graph_unlock())
|
|
return NULL;
|
|
|
|
print_lockdep_off("BUG: MAX_LOCKDEP_ENTRIES too low!");
|
|
dump_stack();
|
|
return NULL;
|
|
}
|
|
return list_entries + nr_list_entries++;
|
|
}
|
|
|
|
/*
|
|
* Add a new dependency to the head of the list:
|
|
*/
|
|
static int add_lock_to_list(struct lock_class *this, struct list_head *head,
|
|
unsigned long ip, int distance,
|
|
struct stack_trace *trace)
|
|
{
|
|
struct lock_list *entry;
|
|
/*
|
|
* Lock not present yet - get a new dependency struct and
|
|
* add it to the list:
|
|
*/
|
|
entry = alloc_list_entry();
|
|
if (!entry)
|
|
return 0;
|
|
|
|
entry->class = this;
|
|
entry->distance = distance;
|
|
entry->trace = *trace;
|
|
/*
|
|
* Both allocation and removal are done under the graph lock; but
|
|
* iteration is under RCU-sched; see look_up_lock_class() and
|
|
* lockdep_free_key_range().
|
|
*/
|
|
list_add_tail_rcu(&entry->entry, head);
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* For good efficiency of modular, we use power of 2
|
|
*/
|
|
#define MAX_CIRCULAR_QUEUE_SIZE 4096UL
|
|
#define CQ_MASK (MAX_CIRCULAR_QUEUE_SIZE-1)
|
|
|
|
/*
|
|
* The circular_queue and helpers is used to implement the
|
|
* breadth-first search(BFS)algorithem, by which we can build
|
|
* the shortest path from the next lock to be acquired to the
|
|
* previous held lock if there is a circular between them.
|
|
*/
|
|
struct circular_queue {
|
|
unsigned long element[MAX_CIRCULAR_QUEUE_SIZE];
|
|
unsigned int front, rear;
|
|
};
|
|
|
|
static struct circular_queue lock_cq;
|
|
|
|
unsigned int max_bfs_queue_depth;
|
|
|
|
static unsigned int lockdep_dependency_gen_id;
|
|
|
|
static inline void __cq_init(struct circular_queue *cq)
|
|
{
|
|
cq->front = cq->rear = 0;
|
|
lockdep_dependency_gen_id++;
|
|
}
|
|
|
|
static inline int __cq_empty(struct circular_queue *cq)
|
|
{
|
|
return (cq->front == cq->rear);
|
|
}
|
|
|
|
static inline int __cq_full(struct circular_queue *cq)
|
|
{
|
|
return ((cq->rear + 1) & CQ_MASK) == cq->front;
|
|
}
|
|
|
|
static inline int __cq_enqueue(struct circular_queue *cq, unsigned long elem)
|
|
{
|
|
if (__cq_full(cq))
|
|
return -1;
|
|
|
|
cq->element[cq->rear] = elem;
|
|
cq->rear = (cq->rear + 1) & CQ_MASK;
|
|
return 0;
|
|
}
|
|
|
|
static inline int __cq_dequeue(struct circular_queue *cq, unsigned long *elem)
|
|
{
|
|
if (__cq_empty(cq))
|
|
return -1;
|
|
|
|
*elem = cq->element[cq->front];
|
|
cq->front = (cq->front + 1) & CQ_MASK;
|
|
return 0;
|
|
}
|
|
|
|
static inline unsigned int __cq_get_elem_count(struct circular_queue *cq)
|
|
{
|
|
return (cq->rear - cq->front) & CQ_MASK;
|
|
}
|
|
|
|
static inline void mark_lock_accessed(struct lock_list *lock,
|
|
struct lock_list *parent)
|
|
{
|
|
unsigned long nr;
|
|
|
|
nr = lock - list_entries;
|
|
WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
|
|
lock->parent = parent;
|
|
lock->class->dep_gen_id = lockdep_dependency_gen_id;
|
|
}
|
|
|
|
static inline unsigned long lock_accessed(struct lock_list *lock)
|
|
{
|
|
unsigned long nr;
|
|
|
|
nr = lock - list_entries;
|
|
WARN_ON(nr >= nr_list_entries); /* Out-of-bounds, input fail */
|
|
return lock->class->dep_gen_id == lockdep_dependency_gen_id;
|
|
}
|
|
|
|
static inline struct lock_list *get_lock_parent(struct lock_list *child)
|
|
{
|
|
return child->parent;
|
|
}
|
|
|
|
static inline int get_lock_depth(struct lock_list *child)
|
|
{
|
|
int depth = 0;
|
|
struct lock_list *parent;
|
|
|
|
while ((parent = get_lock_parent(child))) {
|
|
child = parent;
|
|
depth++;
|
|
}
|
|
return depth;
|
|
}
|
|
|
|
static int __bfs(struct lock_list *source_entry,
|
|
void *data,
|
|
int (*match)(struct lock_list *entry, void *data),
|
|
struct lock_list **target_entry,
|
|
int forward)
|
|
{
|
|
struct lock_list *entry;
|
|
struct list_head *head;
|
|
struct circular_queue *cq = &lock_cq;
|
|
int ret = 1;
|
|
|
|
if (match(source_entry, data)) {
|
|
*target_entry = source_entry;
|
|
ret = 0;
|
|
goto exit;
|
|
}
|
|
|
|
if (forward)
|
|
head = &source_entry->class->locks_after;
|
|
else
|
|
head = &source_entry->class->locks_before;
|
|
|
|
if (list_empty(head))
|
|
goto exit;
|
|
|
|
__cq_init(cq);
|
|
__cq_enqueue(cq, (unsigned long)source_entry);
|
|
|
|
while (!__cq_empty(cq)) {
|
|
struct lock_list *lock;
|
|
|
|
__cq_dequeue(cq, (unsigned long *)&lock);
|
|
|
|
if (!lock->class) {
|
|
ret = -2;
|
|
goto exit;
|
|
}
|
|
|
|
if (forward)
|
|
head = &lock->class->locks_after;
|
|
else
|
|
head = &lock->class->locks_before;
|
|
|
|
DEBUG_LOCKS_WARN_ON(!irqs_disabled());
|
|
|
|
list_for_each_entry_rcu(entry, head, entry) {
|
|
if (!lock_accessed(entry)) {
|
|
unsigned int cq_depth;
|
|
mark_lock_accessed(entry, lock);
|
|
if (match(entry, data)) {
|
|
*target_entry = entry;
|
|
ret = 0;
|
|
goto exit;
|
|
}
|
|
|
|
if (__cq_enqueue(cq, (unsigned long)entry)) {
|
|
ret = -1;
|
|
goto exit;
|
|
}
|
|
cq_depth = __cq_get_elem_count(cq);
|
|
if (max_bfs_queue_depth < cq_depth)
|
|
max_bfs_queue_depth = cq_depth;
|
|
}
|
|
}
|
|
}
|
|
exit:
|
|
return ret;
|
|
}
|
|
|
|
static inline int __bfs_forwards(struct lock_list *src_entry,
|
|
void *data,
|
|
int (*match)(struct lock_list *entry, void *data),
|
|
struct lock_list **target_entry)
|
|
{
|
|
return __bfs(src_entry, data, match, target_entry, 1);
|
|
|
|
}
|
|
|
|
static inline int __bfs_backwards(struct lock_list *src_entry,
|
|
void *data,
|
|
int (*match)(struct lock_list *entry, void *data),
|
|
struct lock_list **target_entry)
|
|
{
|
|
return __bfs(src_entry, data, match, target_entry, 0);
|
|
|
|
}
|
|
|
|
/*
|
|
* Recursive, forwards-direction lock-dependency checking, used for
|
|
* both noncyclic checking and for hardirq-unsafe/softirq-unsafe
|
|
* checking.
|
|
*/
|
|
|
|
/*
|
|
* Print a dependency chain entry (this is only done when a deadlock
|
|
* has been detected):
|
|
*/
|
|
static noinline int
|
|
print_circular_bug_entry(struct lock_list *target, int depth)
|
|
{
|
|
if (debug_locks_silent)
|
|
return 0;
|
|
printk("\n-> #%u", depth);
|
|
print_lock_name(target->class);
|
|
printk(KERN_CONT ":\n");
|
|
print_stack_trace(&target->trace, 6);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void
|
|
print_circular_lock_scenario(struct held_lock *src,
|
|
struct held_lock *tgt,
|
|
struct lock_list *prt)
|
|
{
|
|
struct lock_class *source = hlock_class(src);
|
|
struct lock_class *target = hlock_class(tgt);
|
|
struct lock_class *parent = prt->class;
|
|
|
|
/*
|
|
* A direct locking problem where unsafe_class lock is taken
|
|
* directly by safe_class lock, then all we need to show
|
|
* is the deadlock scenario, as it is obvious that the
|
|
* unsafe lock is taken under the safe lock.
|
|
*
|
|
* But if there is a chain instead, where the safe lock takes
|
|
* an intermediate lock (middle_class) where this lock is
|
|
* not the same as the safe lock, then the lock chain is
|
|
* used to describe the problem. Otherwise we would need
|
|
* to show a different CPU case for each link in the chain
|
|
* from the safe_class lock to the unsafe_class lock.
|
|
*/
|
|
if (parent != source) {
|
|
printk("Chain exists of:\n ");
|
|
__print_lock_name(source);
|
|
printk(KERN_CONT " --> ");
|
|
__print_lock_name(parent);
|
|
printk(KERN_CONT " --> ");
|
|
__print_lock_name(target);
|
|
printk(KERN_CONT "\n\n");
|
|
}
|
|
|
|
if (cross_lock(tgt->instance)) {
|
|
printk(" Possible unsafe locking scenario by crosslock:\n\n");
|
|
printk(" CPU0 CPU1\n");
|
|
printk(" ---- ----\n");
|
|
printk(" lock(");
|
|
__print_lock_name(parent);
|
|
printk(KERN_CONT ");\n");
|
|
printk(" lock(");
|
|
__print_lock_name(target);
|
|
printk(KERN_CONT ");\n");
|
|
printk(" lock(");
|
|
__print_lock_name(source);
|
|
printk(KERN_CONT ");\n");
|
|
printk(" unlock(");
|
|
__print_lock_name(target);
|
|
printk(KERN_CONT ");\n");
|
|
printk("\n *** DEADLOCK ***\n\n");
|
|
} else {
|
|
printk(" Possible unsafe locking scenario:\n\n");
|
|
printk(" CPU0 CPU1\n");
|
|
printk(" ---- ----\n");
|
|
printk(" lock(");
|
|
__print_lock_name(target);
|
|
printk(KERN_CONT ");\n");
|
|
printk(" lock(");
|
|
__print_lock_name(parent);
|
|
printk(KERN_CONT ");\n");
|
|
printk(" lock(");
|
|
__print_lock_name(target);
|
|
printk(KERN_CONT ");\n");
|
|
printk(" lock(");
|
|
__print_lock_name(source);
|
|
printk(KERN_CONT ");\n");
|
|
printk("\n *** DEADLOCK ***\n\n");
|
|
}
|
|
}
|
|
|
|
/*
|
|
* When a circular dependency is detected, print the
|
|
* header first:
|
|
*/
|
|
static noinline int
|
|
print_circular_bug_header(struct lock_list *entry, unsigned int depth,
|
|
struct held_lock *check_src,
|
|
struct held_lock *check_tgt)
|
|
{
|
|
struct task_struct *curr = current;
|
|
|
|
if (debug_locks_silent)
|
|
return 0;
|
|
|
|
pr_warn("\n");
|
|
pr_warn("======================================================\n");
|
|
pr_warn("WARNING: possible circular locking dependency detected\n");
|
|
print_kernel_ident();
|
|
pr_warn("------------------------------------------------------\n");
|
|
pr_warn("%s/%d is trying to acquire lock:\n",
|
|
curr->comm, task_pid_nr(curr));
|
|
print_lock(check_src);
|
|
|
|
if (cross_lock(check_tgt->instance))
|
|
pr_warn("\nbut now in release context of a crosslock acquired at the following:\n");
|
|
else
|
|
pr_warn("\nbut task is already holding lock:\n");
|
|
|
|
print_lock(check_tgt);
|
|
pr_warn("\nwhich lock already depends on the new lock.\n\n");
|
|
pr_warn("\nthe existing dependency chain (in reverse order) is:\n");
|
|
|
|
print_circular_bug_entry(entry, depth);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static inline int class_equal(struct lock_list *entry, void *data)
|
|
{
|
|
return entry->class == data;
|
|
}
|
|
|
|
static noinline int print_circular_bug(struct lock_list *this,
|
|
struct lock_list *target,
|
|
struct held_lock *check_src,
|
|
struct held_lock *check_tgt,
|
|
struct stack_trace *trace)
|
|
{
|
|
struct task_struct *curr = current;
|
|
struct lock_list *parent;
|
|
struct lock_list *first_parent;
|
|
int depth;
|
|
|
|
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
|
|
return 0;
|
|
|
|
if (cross_lock(check_tgt->instance))
|
|
this->trace = *trace;
|
|
else if (!save_trace(&this->trace))
|
|
return 0;
|
|
|
|
depth = get_lock_depth(target);
|
|
|
|
print_circular_bug_header(target, depth, check_src, check_tgt);
|
|
|
|
parent = get_lock_parent(target);
|
|
first_parent = parent;
|
|
|
|
while (parent) {
|
|
print_circular_bug_entry(parent, --depth);
|
|
parent = get_lock_parent(parent);
|
|
}
|
|
|
|
printk("\nother info that might help us debug this:\n\n");
|
|
print_circular_lock_scenario(check_src, check_tgt,
|
|
first_parent);
|
|
|
|
lockdep_print_held_locks(curr);
|
|
|
|
printk("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static noinline int print_bfs_bug(int ret)
|
|
{
|
|
if (!debug_locks_off_graph_unlock())
|
|
return 0;
|
|
|
|
/*
|
|
* Breadth-first-search failed, graph got corrupted?
|
|
*/
|
|
WARN(1, "lockdep bfs error:%d\n", ret);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int noop_count(struct lock_list *entry, void *data)
|
|
{
|
|
(*(unsigned long *)data)++;
|
|
return 0;
|
|
}
|
|
|
|
static unsigned long __lockdep_count_forward_deps(struct lock_list *this)
|
|
{
|
|
unsigned long count = 0;
|
|
struct lock_list *uninitialized_var(target_entry);
|
|
|
|
__bfs_forwards(this, (void *)&count, noop_count, &target_entry);
|
|
|
|
return count;
|
|
}
|
|
unsigned long lockdep_count_forward_deps(struct lock_class *class)
|
|
{
|
|
unsigned long ret, flags;
|
|
struct lock_list this;
|
|
|
|
this.parent = NULL;
|
|
this.class = class;
|
|
|
|
local_irq_save(flags);
|
|
arch_spin_lock(&lockdep_lock);
|
|
ret = __lockdep_count_forward_deps(&this);
|
|
arch_spin_unlock(&lockdep_lock);
|
|
local_irq_restore(flags);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static unsigned long __lockdep_count_backward_deps(struct lock_list *this)
|
|
{
|
|
unsigned long count = 0;
|
|
struct lock_list *uninitialized_var(target_entry);
|
|
|
|
__bfs_backwards(this, (void *)&count, noop_count, &target_entry);
|
|
|
|
return count;
|
|
}
|
|
|
|
unsigned long lockdep_count_backward_deps(struct lock_class *class)
|
|
{
|
|
unsigned long ret, flags;
|
|
struct lock_list this;
|
|
|
|
this.parent = NULL;
|
|
this.class = class;
|
|
|
|
local_irq_save(flags);
|
|
arch_spin_lock(&lockdep_lock);
|
|
ret = __lockdep_count_backward_deps(&this);
|
|
arch_spin_unlock(&lockdep_lock);
|
|
local_irq_restore(flags);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Prove that the dependency graph starting at <entry> can not
|
|
* lead to <target>. Print an error and return 0 if it does.
|
|
*/
|
|
static noinline int
|
|
check_noncircular(struct lock_list *root, struct lock_class *target,
|
|
struct lock_list **target_entry)
|
|
{
|
|
int result;
|
|
|
|
debug_atomic_inc(nr_cyclic_checks);
|
|
|
|
result = __bfs_forwards(root, target, class_equal, target_entry);
|
|
|
|
return result;
|
|
}
|
|
|
|
static noinline int
|
|
check_redundant(struct lock_list *root, struct lock_class *target,
|
|
struct lock_list **target_entry)
|
|
{
|
|
int result;
|
|
|
|
debug_atomic_inc(nr_redundant_checks);
|
|
|
|
result = __bfs_forwards(root, target, class_equal, target_entry);
|
|
|
|
return result;
|
|
}
|
|
|
|
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
|
|
/*
|
|
* Forwards and backwards subgraph searching, for the purposes of
|
|
* proving that two subgraphs can be connected by a new dependency
|
|
* without creating any illegal irq-safe -> irq-unsafe lock dependency.
|
|
*/
|
|
|
|
static inline int usage_match(struct lock_list *entry, void *bit)
|
|
{
|
|
return entry->class->usage_mask & (1 << (enum lock_usage_bit)bit);
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
* Find a node in the forwards-direction dependency sub-graph starting
|
|
* at @root->class that matches @bit.
|
|
*
|
|
* Return 0 if such a node exists in the subgraph, and put that node
|
|
* into *@target_entry.
|
|
*
|
|
* Return 1 otherwise and keep *@target_entry unchanged.
|
|
* Return <0 on error.
|
|
*/
|
|
static int
|
|
find_usage_forwards(struct lock_list *root, enum lock_usage_bit bit,
|
|
struct lock_list **target_entry)
|
|
{
|
|
int result;
|
|
|
|
debug_atomic_inc(nr_find_usage_forwards_checks);
|
|
|
|
result = __bfs_forwards(root, (void *)bit, usage_match, target_entry);
|
|
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* Find a node in the backwards-direction dependency sub-graph starting
|
|
* at @root->class that matches @bit.
|
|
*
|
|
* Return 0 if such a node exists in the subgraph, and put that node
|
|
* into *@target_entry.
|
|
*
|
|
* Return 1 otherwise and keep *@target_entry unchanged.
|
|
* Return <0 on error.
|
|
*/
|
|
static int
|
|
find_usage_backwards(struct lock_list *root, enum lock_usage_bit bit,
|
|
struct lock_list **target_entry)
|
|
{
|
|
int result;
|
|
|
|
debug_atomic_inc(nr_find_usage_backwards_checks);
|
|
|
|
result = __bfs_backwards(root, (void *)bit, usage_match, target_entry);
|
|
|
|
return result;
|
|
}
|
|
|
|
static void print_lock_class_header(struct lock_class *class, int depth)
|
|
{
|
|
int bit;
|
|
|
|
printk("%*s->", depth, "");
|
|
print_lock_name(class);
|
|
printk(KERN_CONT " ops: %lu", class->ops);
|
|
printk(KERN_CONT " {\n");
|
|
|
|
for (bit = 0; bit < LOCK_USAGE_STATES; bit++) {
|
|
if (class->usage_mask & (1 << bit)) {
|
|
int len = depth;
|
|
|
|
len += printk("%*s %s", depth, "", usage_str[bit]);
|
|
len += printk(KERN_CONT " at:\n");
|
|
print_stack_trace(class->usage_traces + bit, len);
|
|
}
|
|
}
|
|
printk("%*s }\n", depth, "");
|
|
|
|
printk("%*s ... key at: [<%p>] %pS\n",
|
|
depth, "", class->key, class->key);
|
|
}
|
|
|
|
/*
|
|
* printk the shortest lock dependencies from @start to @end in reverse order:
|
|
*/
|
|
static void __used
|
|
print_shortest_lock_dependencies(struct lock_list *leaf,
|
|
struct lock_list *root)
|
|
{
|
|
struct lock_list *entry = leaf;
|
|
int depth;
|
|
|
|
/*compute depth from generated tree by BFS*/
|
|
depth = get_lock_depth(leaf);
|
|
|
|
do {
|
|
print_lock_class_header(entry->class, depth);
|
|
printk("%*s ... acquired at:\n", depth, "");
|
|
print_stack_trace(&entry->trace, 2);
|
|
printk("\n");
|
|
|
|
if (depth == 0 && (entry != root)) {
|
|
printk("lockdep:%s bad path found in chain graph\n", __func__);
|
|
break;
|
|
}
|
|
|
|
entry = get_lock_parent(entry);
|
|
depth--;
|
|
} while (entry && (depth >= 0));
|
|
|
|
return;
|
|
}
|
|
|
|
static void
|
|
print_irq_lock_scenario(struct lock_list *safe_entry,
|
|
struct lock_list *unsafe_entry,
|
|
struct lock_class *prev_class,
|
|
struct lock_class *next_class)
|
|
{
|
|
struct lock_class *safe_class = safe_entry->class;
|
|
struct lock_class *unsafe_class = unsafe_entry->class;
|
|
struct lock_class *middle_class = prev_class;
|
|
|
|
if (middle_class == safe_class)
|
|
middle_class = next_class;
|
|
|
|
/*
|
|
* A direct locking problem where unsafe_class lock is taken
|
|
* directly by safe_class lock, then all we need to show
|
|
* is the deadlock scenario, as it is obvious that the
|
|
* unsafe lock is taken under the safe lock.
|
|
*
|
|
* But if there is a chain instead, where the safe lock takes
|
|
* an intermediate lock (middle_class) where this lock is
|
|
* not the same as the safe lock, then the lock chain is
|
|
* used to describe the problem. Otherwise we would need
|
|
* to show a different CPU case for each link in the chain
|
|
* from the safe_class lock to the unsafe_class lock.
|
|
*/
|
|
if (middle_class != unsafe_class) {
|
|
printk("Chain exists of:\n ");
|
|
__print_lock_name(safe_class);
|
|
printk(KERN_CONT " --> ");
|
|
__print_lock_name(middle_class);
|
|
printk(KERN_CONT " --> ");
|
|
__print_lock_name(unsafe_class);
|
|
printk(KERN_CONT "\n\n");
|
|
}
|
|
|
|
printk(" Possible interrupt unsafe locking scenario:\n\n");
|
|
printk(" CPU0 CPU1\n");
|
|
printk(" ---- ----\n");
|
|
printk(" lock(");
|
|
__print_lock_name(unsafe_class);
|
|
printk(KERN_CONT ");\n");
|
|
printk(" local_irq_disable();\n");
|
|
printk(" lock(");
|
|
__print_lock_name(safe_class);
|
|
printk(KERN_CONT ");\n");
|
|
printk(" lock(");
|
|
__print_lock_name(middle_class);
|
|
printk(KERN_CONT ");\n");
|
|
printk(" <Interrupt>\n");
|
|
printk(" lock(");
|
|
__print_lock_name(safe_class);
|
|
printk(KERN_CONT ");\n");
|
|
printk("\n *** DEADLOCK ***\n\n");
|
|
}
|
|
|
|
static int
|
|
print_bad_irq_dependency(struct task_struct *curr,
|
|
struct lock_list *prev_root,
|
|
struct lock_list *next_root,
|
|
struct lock_list *backwards_entry,
|
|
struct lock_list *forwards_entry,
|
|
struct held_lock *prev,
|
|
struct held_lock *next,
|
|
enum lock_usage_bit bit1,
|
|
enum lock_usage_bit bit2,
|
|
const char *irqclass)
|
|
{
|
|
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
|
|
return 0;
|
|
|
|
pr_warn("\n");
|
|
pr_warn("=====================================================\n");
|
|
pr_warn("WARNING: %s-safe -> %s-unsafe lock order detected\n",
|
|
irqclass, irqclass);
|
|
print_kernel_ident();
|
|
pr_warn("-----------------------------------------------------\n");
|
|
pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] is trying to acquire:\n",
|
|
curr->comm, task_pid_nr(curr),
|
|
curr->hardirq_context, hardirq_count() >> HARDIRQ_SHIFT,
|
|
curr->softirq_context, softirq_count() >> SOFTIRQ_SHIFT,
|
|
curr->hardirqs_enabled,
|
|
curr->softirqs_enabled);
|
|
print_lock(next);
|
|
|
|
pr_warn("\nand this task is already holding:\n");
|
|
print_lock(prev);
|
|
pr_warn("which would create a new lock dependency:\n");
|
|
print_lock_name(hlock_class(prev));
|
|
pr_cont(" ->");
|
|
print_lock_name(hlock_class(next));
|
|
pr_cont("\n");
|
|
|
|
pr_warn("\nbut this new dependency connects a %s-irq-safe lock:\n",
|
|
irqclass);
|
|
print_lock_name(backwards_entry->class);
|
|
pr_warn("\n... which became %s-irq-safe at:\n", irqclass);
|
|
|
|
print_stack_trace(backwards_entry->class->usage_traces + bit1, 1);
|
|
|
|
pr_warn("\nto a %s-irq-unsafe lock:\n", irqclass);
|
|
print_lock_name(forwards_entry->class);
|
|
pr_warn("\n... which became %s-irq-unsafe at:\n", irqclass);
|
|
pr_warn("...");
|
|
|
|
print_stack_trace(forwards_entry->class->usage_traces + bit2, 1);
|
|
|
|
pr_warn("\nother info that might help us debug this:\n\n");
|
|
print_irq_lock_scenario(backwards_entry, forwards_entry,
|
|
hlock_class(prev), hlock_class(next));
|
|
|
|
lockdep_print_held_locks(curr);
|
|
|
|
pr_warn("\nthe dependencies between %s-irq-safe lock and the holding lock:\n", irqclass);
|
|
if (!save_trace(&prev_root->trace))
|
|
return 0;
|
|
print_shortest_lock_dependencies(backwards_entry, prev_root);
|
|
|
|
pr_warn("\nthe dependencies between the lock to be acquired");
|
|
pr_warn(" and %s-irq-unsafe lock:\n", irqclass);
|
|
if (!save_trace(&next_root->trace))
|
|
return 0;
|
|
print_shortest_lock_dependencies(forwards_entry, next_root);
|
|
|
|
pr_warn("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
check_usage(struct task_struct *curr, struct held_lock *prev,
|
|
struct held_lock *next, enum lock_usage_bit bit_backwards,
|
|
enum lock_usage_bit bit_forwards, const char *irqclass)
|
|
{
|
|
int ret;
|
|
struct lock_list this, that;
|
|
struct lock_list *uninitialized_var(target_entry);
|
|
struct lock_list *uninitialized_var(target_entry1);
|
|
|
|
this.parent = NULL;
|
|
|
|
this.class = hlock_class(prev);
|
|
ret = find_usage_backwards(&this, bit_backwards, &target_entry);
|
|
if (ret < 0)
|
|
return print_bfs_bug(ret);
|
|
if (ret == 1)
|
|
return ret;
|
|
|
|
that.parent = NULL;
|
|
that.class = hlock_class(next);
|
|
ret = find_usage_forwards(&that, bit_forwards, &target_entry1);
|
|
if (ret < 0)
|
|
return print_bfs_bug(ret);
|
|
if (ret == 1)
|
|
return ret;
|
|
|
|
return print_bad_irq_dependency(curr, &this, &that,
|
|
target_entry, target_entry1,
|
|
prev, next,
|
|
bit_backwards, bit_forwards, irqclass);
|
|
}
|
|
|
|
static const char *state_names[] = {
|
|
#define LOCKDEP_STATE(__STATE) \
|
|
__stringify(__STATE),
|
|
#include "lockdep_states.h"
|
|
#undef LOCKDEP_STATE
|
|
};
|
|
|
|
static const char *state_rnames[] = {
|
|
#define LOCKDEP_STATE(__STATE) \
|
|
__stringify(__STATE)"-READ",
|
|
#include "lockdep_states.h"
|
|
#undef LOCKDEP_STATE
|
|
};
|
|
|
|
static inline const char *state_name(enum lock_usage_bit bit)
|
|
{
|
|
return (bit & 1) ? state_rnames[bit >> 2] : state_names[bit >> 2];
|
|
}
|
|
|
|
static int exclusive_bit(int new_bit)
|
|
{
|
|
/*
|
|
* USED_IN
|
|
* USED_IN_READ
|
|
* ENABLED
|
|
* ENABLED_READ
|
|
*
|
|
* bit 0 - write/read
|
|
* bit 1 - used_in/enabled
|
|
* bit 2+ state
|
|
*/
|
|
|
|
int state = new_bit & ~3;
|
|
int dir = new_bit & 2;
|
|
|
|
/*
|
|
* keep state, bit flip the direction and strip read.
|
|
*/
|
|
return state | (dir ^ 2);
|
|
}
|
|
|
|
static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
|
|
struct held_lock *next, enum lock_usage_bit bit)
|
|
{
|
|
/*
|
|
* Prove that the new dependency does not connect a hardirq-safe
|
|
* lock with a hardirq-unsafe lock - to achieve this we search
|
|
* the backwards-subgraph starting at <prev>, and the
|
|
* forwards-subgraph starting at <next>:
|
|
*/
|
|
if (!check_usage(curr, prev, next, bit,
|
|
exclusive_bit(bit), state_name(bit)))
|
|
return 0;
|
|
|
|
bit++; /* _READ */
|
|
|
|
/*
|
|
* Prove that the new dependency does not connect a hardirq-safe-read
|
|
* lock with a hardirq-unsafe lock - to achieve this we search
|
|
* the backwards-subgraph starting at <prev>, and the
|
|
* forwards-subgraph starting at <next>:
|
|
*/
|
|
if (!check_usage(curr, prev, next, bit,
|
|
exclusive_bit(bit), state_name(bit)))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int
|
|
check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
|
|
struct held_lock *next)
|
|
{
|
|
#define LOCKDEP_STATE(__STATE) \
|
|
if (!check_irq_usage(curr, prev, next, LOCK_USED_IN_##__STATE)) \
|
|
return 0;
|
|
#include "lockdep_states.h"
|
|
#undef LOCKDEP_STATE
|
|
|
|
return 1;
|
|
}
|
|
|
|
static void inc_chains(void)
|
|
{
|
|
if (current->hardirq_context)
|
|
nr_hardirq_chains++;
|
|
else {
|
|
if (current->softirq_context)
|
|
nr_softirq_chains++;
|
|
else
|
|
nr_process_chains++;
|
|
}
|
|
}
|
|
|
|
#else
|
|
|
|
static inline int
|
|
check_prev_add_irq(struct task_struct *curr, struct held_lock *prev,
|
|
struct held_lock *next)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
static inline void inc_chains(void)
|
|
{
|
|
nr_process_chains++;
|
|
}
|
|
|
|
#endif
|
|
|
|
static void
|
|
print_deadlock_scenario(struct held_lock *nxt,
|
|
struct held_lock *prv)
|
|
{
|
|
struct lock_class *next = hlock_class(nxt);
|
|
struct lock_class *prev = hlock_class(prv);
|
|
|
|
printk(" Possible unsafe locking scenario:\n\n");
|
|
printk(" CPU0\n");
|
|
printk(" ----\n");
|
|
printk(" lock(");
|
|
__print_lock_name(prev);
|
|
printk(KERN_CONT ");\n");
|
|
printk(" lock(");
|
|
__print_lock_name(next);
|
|
printk(KERN_CONT ");\n");
|
|
printk("\n *** DEADLOCK ***\n\n");
|
|
printk(" May be due to missing lock nesting notation\n\n");
|
|
}
|
|
|
|
static int
|
|
print_deadlock_bug(struct task_struct *curr, struct held_lock *prev,
|
|
struct held_lock *next)
|
|
{
|
|
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
|
|
return 0;
|
|
|
|
pr_warn("\n");
|
|
pr_warn("============================================\n");
|
|
pr_warn("WARNING: possible recursive locking detected\n");
|
|
print_kernel_ident();
|
|
pr_warn("--------------------------------------------\n");
|
|
pr_warn("%s/%d is trying to acquire lock:\n",
|
|
curr->comm, task_pid_nr(curr));
|
|
print_lock(next);
|
|
pr_warn("\nbut task is already holding lock:\n");
|
|
print_lock(prev);
|
|
|
|
pr_warn("\nother info that might help us debug this:\n");
|
|
print_deadlock_scenario(next, prev);
|
|
lockdep_print_held_locks(curr);
|
|
|
|
pr_warn("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Check whether we are holding such a class already.
|
|
*
|
|
* (Note that this has to be done separately, because the graph cannot
|
|
* detect such classes of deadlocks.)
|
|
*
|
|
* Returns: 0 on deadlock detected, 1 on OK, 2 on recursive read
|
|
*/
|
|
static int
|
|
check_deadlock(struct task_struct *curr, struct held_lock *next,
|
|
struct lockdep_map *next_instance, int read)
|
|
{
|
|
struct held_lock *prev;
|
|
struct held_lock *nest = NULL;
|
|
int i;
|
|
|
|
for (i = 0; i < curr->lockdep_depth; i++) {
|
|
prev = curr->held_locks + i;
|
|
|
|
if (prev->instance == next->nest_lock)
|
|
nest = prev;
|
|
|
|
if (hlock_class(prev) != hlock_class(next))
|
|
continue;
|
|
|
|
/*
|
|
* Allow read-after-read recursion of the same
|
|
* lock class (i.e. read_lock(lock)+read_lock(lock)):
|
|
*/
|
|
if ((read == 2) && prev->read)
|
|
return 2;
|
|
|
|
/*
|
|
* We're holding the nest_lock, which serializes this lock's
|
|
* nesting behaviour.
|
|
*/
|
|
if (nest)
|
|
return 2;
|
|
|
|
if (cross_lock(prev->instance))
|
|
continue;
|
|
|
|
return print_deadlock_bug(curr, prev, next);
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* There was a chain-cache miss, and we are about to add a new dependency
|
|
* to a previous lock. We recursively validate the following rules:
|
|
*
|
|
* - would the adding of the <prev> -> <next> dependency create a
|
|
* circular dependency in the graph? [== circular deadlock]
|
|
*
|
|
* - does the new prev->next dependency connect any hardirq-safe lock
|
|
* (in the full backwards-subgraph starting at <prev>) with any
|
|
* hardirq-unsafe lock (in the full forwards-subgraph starting at
|
|
* <next>)? [== illegal lock inversion with hardirq contexts]
|
|
*
|
|
* - does the new prev->next dependency connect any softirq-safe lock
|
|
* (in the full backwards-subgraph starting at <prev>) with any
|
|
* softirq-unsafe lock (in the full forwards-subgraph starting at
|
|
* <next>)? [== illegal lock inversion with softirq contexts]
|
|
*
|
|
* any of these scenarios could lead to a deadlock.
|
|
*
|
|
* Then if all the validations pass, we add the forwards and backwards
|
|
* dependency.
|
|
*/
|
|
static int
|
|
check_prev_add(struct task_struct *curr, struct held_lock *prev,
|
|
struct held_lock *next, int distance, struct stack_trace *trace,
|
|
int (*save)(struct stack_trace *trace))
|
|
{
|
|
struct lock_list *uninitialized_var(target_entry);
|
|
struct lock_list *entry;
|
|
struct lock_list this;
|
|
int ret;
|
|
|
|
/*
|
|
* Prove that the new <prev> -> <next> dependency would not
|
|
* create a circular dependency in the graph. (We do this by
|
|
* forward-recursing into the graph starting at <next>, and
|
|
* checking whether we can reach <prev>.)
|
|
*
|
|
* We are using global variables to control the recursion, to
|
|
* keep the stackframe size of the recursive functions low:
|
|
*/
|
|
this.class = hlock_class(next);
|
|
this.parent = NULL;
|
|
ret = check_noncircular(&this, hlock_class(prev), &target_entry);
|
|
if (unlikely(!ret)) {
|
|
if (!trace->entries) {
|
|
/*
|
|
* If @save fails here, the printing might trigger
|
|
* a WARN but because of the !nr_entries it should
|
|
* not do bad things.
|
|
*/
|
|
save(trace);
|
|
}
|
|
return print_circular_bug(&this, target_entry, next, prev, trace);
|
|
}
|
|
else if (unlikely(ret < 0))
|
|
return print_bfs_bug(ret);
|
|
|
|
if (!check_prev_add_irq(curr, prev, next))
|
|
return 0;
|
|
|
|
/*
|
|
* For recursive read-locks we do all the dependency checks,
|
|
* but we dont store read-triggered dependencies (only
|
|
* write-triggered dependencies). This ensures that only the
|
|
* write-side dependencies matter, and that if for example a
|
|
* write-lock never takes any other locks, then the reads are
|
|
* equivalent to a NOP.
|
|
*/
|
|
if (next->read == 2 || prev->read == 2)
|
|
return 1;
|
|
/*
|
|
* Is the <prev> -> <next> dependency already present?
|
|
*
|
|
* (this may occur even though this is a new chain: consider
|
|
* e.g. the L1 -> L2 -> L3 -> L4 and the L5 -> L1 -> L2 -> L3
|
|
* chains - the second one will be new, but L1 already has
|
|
* L2 added to its dependency list, due to the first chain.)
|
|
*/
|
|
list_for_each_entry(entry, &hlock_class(prev)->locks_after, entry) {
|
|
if (entry->class == hlock_class(next)) {
|
|
if (distance == 1)
|
|
entry->distance = 1;
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Is the <prev> -> <next> link redundant?
|
|
*/
|
|
this.class = hlock_class(prev);
|
|
this.parent = NULL;
|
|
ret = check_redundant(&this, hlock_class(next), &target_entry);
|
|
if (!ret) {
|
|
debug_atomic_inc(nr_redundant);
|
|
return 2;
|
|
}
|
|
if (ret < 0)
|
|
return print_bfs_bug(ret);
|
|
|
|
|
|
if (!trace->entries && !save(trace))
|
|
return 0;
|
|
|
|
/*
|
|
* Ok, all validations passed, add the new lock
|
|
* to the previous lock's dependency list:
|
|
*/
|
|
ret = add_lock_to_list(hlock_class(next),
|
|
&hlock_class(prev)->locks_after,
|
|
next->acquire_ip, distance, trace);
|
|
|
|
if (!ret)
|
|
return 0;
|
|
|
|
ret = add_lock_to_list(hlock_class(prev),
|
|
&hlock_class(next)->locks_before,
|
|
next->acquire_ip, distance, trace);
|
|
if (!ret)
|
|
return 0;
|
|
|
|
return 2;
|
|
}
|
|
|
|
/*
|
|
* Add the dependency to all directly-previous locks that are 'relevant'.
|
|
* The ones that are relevant are (in increasing distance from curr):
|
|
* all consecutive trylock entries and the final non-trylock entry - or
|
|
* the end of this context's lock-chain - whichever comes first.
|
|
*/
|
|
static int
|
|
check_prevs_add(struct task_struct *curr, struct held_lock *next)
|
|
{
|
|
int depth = curr->lockdep_depth;
|
|
struct held_lock *hlock;
|
|
struct stack_trace trace = {
|
|
.nr_entries = 0,
|
|
.max_entries = 0,
|
|
.entries = NULL,
|
|
.skip = 0,
|
|
};
|
|
|
|
/*
|
|
* Debugging checks.
|
|
*
|
|
* Depth must not be zero for a non-head lock:
|
|
*/
|
|
if (!depth)
|
|
goto out_bug;
|
|
/*
|
|
* At least two relevant locks must exist for this
|
|
* to be a head:
|
|
*/
|
|
if (curr->held_locks[depth].irq_context !=
|
|
curr->held_locks[depth-1].irq_context)
|
|
goto out_bug;
|
|
|
|
for (;;) {
|
|
int distance = curr->lockdep_depth - depth + 1;
|
|
hlock = curr->held_locks + depth - 1;
|
|
/*
|
|
* Only non-crosslock entries get new dependencies added.
|
|
* Crosslock entries will be added by commit later:
|
|
*/
|
|
if (!cross_lock(hlock->instance)) {
|
|
/*
|
|
* Only non-recursive-read entries get new dependencies
|
|
* added:
|
|
*/
|
|
if (hlock->read != 2 && hlock->check) {
|
|
int ret = check_prev_add(curr, hlock, next,
|
|
distance, &trace, save_trace);
|
|
if (!ret)
|
|
return 0;
|
|
|
|
/*
|
|
* Stop after the first non-trylock entry,
|
|
* as non-trylock entries have added their
|
|
* own direct dependencies already, so this
|
|
* lock is connected to them indirectly:
|
|
*/
|
|
if (!hlock->trylock)
|
|
break;
|
|
}
|
|
}
|
|
depth--;
|
|
/*
|
|
* End of lock-stack?
|
|
*/
|
|
if (!depth)
|
|
break;
|
|
/*
|
|
* Stop the search if we cross into another context:
|
|
*/
|
|
if (curr->held_locks[depth].irq_context !=
|
|
curr->held_locks[depth-1].irq_context)
|
|
break;
|
|
}
|
|
return 1;
|
|
out_bug:
|
|
if (!debug_locks_off_graph_unlock())
|
|
return 0;
|
|
|
|
/*
|
|
* Clearly we all shouldn't be here, but since we made it we
|
|
* can reliable say we messed up our state. See the above two
|
|
* gotos for reasons why we could possibly end up here.
|
|
*/
|
|
WARN_ON(1);
|
|
|
|
return 0;
|
|
}
|
|
|
|
unsigned long nr_lock_chains;
|
|
struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS];
|
|
int nr_chain_hlocks;
|
|
static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS];
|
|
|
|
struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i)
|
|
{
|
|
return lock_classes + chain_hlocks[chain->base + i];
|
|
}
|
|
|
|
/*
|
|
* Returns the index of the first held_lock of the current chain
|
|
*/
|
|
static inline int get_first_held_lock(struct task_struct *curr,
|
|
struct held_lock *hlock)
|
|
{
|
|
int i;
|
|
struct held_lock *hlock_curr;
|
|
|
|
for (i = curr->lockdep_depth - 1; i >= 0; i--) {
|
|
hlock_curr = curr->held_locks + i;
|
|
if (hlock_curr->irq_context != hlock->irq_context)
|
|
break;
|
|
|
|
}
|
|
|
|
return ++i;
|
|
}
|
|
|
|
#ifdef CONFIG_DEBUG_LOCKDEP
|
|
/*
|
|
* Returns the next chain_key iteration
|
|
*/
|
|
static u64 print_chain_key_iteration(int class_idx, u64 chain_key)
|
|
{
|
|
u64 new_chain_key = iterate_chain_key(chain_key, class_idx);
|
|
|
|
printk(" class_idx:%d -> chain_key:%016Lx",
|
|
class_idx,
|
|
(unsigned long long)new_chain_key);
|
|
return new_chain_key;
|
|
}
|
|
|
|
static void
|
|
print_chain_keys_held_locks(struct task_struct *curr, struct held_lock *hlock_next)
|
|
{
|
|
struct held_lock *hlock;
|
|
u64 chain_key = 0;
|
|
int depth = curr->lockdep_depth;
|
|
int i;
|
|
|
|
printk("depth: %u\n", depth + 1);
|
|
for (i = get_first_held_lock(curr, hlock_next); i < depth; i++) {
|
|
hlock = curr->held_locks + i;
|
|
chain_key = print_chain_key_iteration(hlock->class_idx, chain_key);
|
|
|
|
print_lock(hlock);
|
|
}
|
|
|
|
print_chain_key_iteration(hlock_next->class_idx, chain_key);
|
|
print_lock(hlock_next);
|
|
}
|
|
|
|
static void print_chain_keys_chain(struct lock_chain *chain)
|
|
{
|
|
int i;
|
|
u64 chain_key = 0;
|
|
int class_id;
|
|
|
|
printk("depth: %u\n", chain->depth);
|
|
for (i = 0; i < chain->depth; i++) {
|
|
class_id = chain_hlocks[chain->base + i];
|
|
chain_key = print_chain_key_iteration(class_id + 1, chain_key);
|
|
|
|
print_lock_name(lock_classes + class_id);
|
|
printk("\n");
|
|
}
|
|
}
|
|
|
|
static void print_collision(struct task_struct *curr,
|
|
struct held_lock *hlock_next,
|
|
struct lock_chain *chain)
|
|
{
|
|
pr_warn("\n");
|
|
pr_warn("============================\n");
|
|
pr_warn("WARNING: chain_key collision\n");
|
|
print_kernel_ident();
|
|
pr_warn("----------------------------\n");
|
|
pr_warn("%s/%d: ", current->comm, task_pid_nr(current));
|
|
pr_warn("Hash chain already cached but the contents don't match!\n");
|
|
|
|
pr_warn("Held locks:");
|
|
print_chain_keys_held_locks(curr, hlock_next);
|
|
|
|
pr_warn("Locks in cached chain:");
|
|
print_chain_keys_chain(chain);
|
|
|
|
pr_warn("\nstack backtrace:\n");
|
|
dump_stack();
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Checks whether the chain and the current held locks are consistent
|
|
* in depth and also in content. If they are not it most likely means
|
|
* that there was a collision during the calculation of the chain_key.
|
|
* Returns: 0 not passed, 1 passed
|
|
*/
|
|
static int check_no_collision(struct task_struct *curr,
|
|
struct held_lock *hlock,
|
|
struct lock_chain *chain)
|
|
{
|
|
#ifdef CONFIG_DEBUG_LOCKDEP
|
|
int i, j, id;
|
|
|
|
i = get_first_held_lock(curr, hlock);
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(chain->depth != curr->lockdep_depth - (i - 1))) {
|
|
print_collision(curr, hlock, chain);
|
|
return 0;
|
|
}
|
|
|
|
for (j = 0; j < chain->depth - 1; j++, i++) {
|
|
id = curr->held_locks[i].class_idx - 1;
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(chain_hlocks[chain->base + j] != id)) {
|
|
print_collision(curr, hlock, chain);
|
|
return 0;
|
|
}
|
|
}
|
|
#endif
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* This is for building a chain between just two different classes,
|
|
* instead of adding a new hlock upon current, which is done by
|
|
* add_chain_cache().
|
|
*
|
|
* This can be called in any context with two classes, while
|
|
* add_chain_cache() must be done within the lock owener's context
|
|
* since it uses hlock which might be racy in another context.
|
|
*/
|
|
static inline int add_chain_cache_classes(unsigned int prev,
|
|
unsigned int next,
|
|
unsigned int irq_context,
|
|
u64 chain_key)
|
|
{
|
|
struct hlist_head *hash_head = chainhashentry(chain_key);
|
|
struct lock_chain *chain;
|
|
|
|
/*
|
|
* Allocate a new chain entry from the static array, and add
|
|
* it to the hash:
|
|
*/
|
|
|
|
/*
|
|
* We might need to take the graph lock, ensure we've got IRQs
|
|
* disabled to make this an IRQ-safe lock.. for recursion reasons
|
|
* lockdep won't complain about its own locking errors.
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return 0;
|
|
|
|
if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
|
|
if (!debug_locks_off_graph_unlock())
|
|
return 0;
|
|
|
|
print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
|
|
dump_stack();
|
|
return 0;
|
|
}
|
|
|
|
chain = lock_chains + nr_lock_chains++;
|
|
chain->chain_key = chain_key;
|
|
chain->irq_context = irq_context;
|
|
chain->depth = 2;
|
|
if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
|
|
chain->base = nr_chain_hlocks;
|
|
nr_chain_hlocks += chain->depth;
|
|
chain_hlocks[chain->base] = prev - 1;
|
|
chain_hlocks[chain->base + 1] = next -1;
|
|
}
|
|
#ifdef CONFIG_DEBUG_LOCKDEP
|
|
/*
|
|
* Important for check_no_collision().
|
|
*/
|
|
else {
|
|
if (!debug_locks_off_graph_unlock())
|
|
return 0;
|
|
|
|
print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
|
|
dump_stack();
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
hlist_add_head_rcu(&chain->entry, hash_head);
|
|
debug_atomic_inc(chain_lookup_misses);
|
|
inc_chains();
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Adds a dependency chain into chain hashtable. And must be called with
|
|
* graph_lock held.
|
|
*
|
|
* Return 0 if fail, and graph_lock is released.
|
|
* Return 1 if succeed, with graph_lock held.
|
|
*/
|
|
static inline int add_chain_cache(struct task_struct *curr,
|
|
struct held_lock *hlock,
|
|
u64 chain_key)
|
|
{
|
|
struct lock_class *class = hlock_class(hlock);
|
|
struct hlist_head *hash_head = chainhashentry(chain_key);
|
|
struct lock_chain *chain;
|
|
int i, j;
|
|
|
|
/*
|
|
* Allocate a new chain entry from the static array, and add
|
|
* it to the hash:
|
|
*/
|
|
|
|
/*
|
|
* We might need to take the graph lock, ensure we've got IRQs
|
|
* disabled to make this an IRQ-safe lock.. for recursion reasons
|
|
* lockdep won't complain about its own locking errors.
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return 0;
|
|
|
|
if (unlikely(nr_lock_chains >= MAX_LOCKDEP_CHAINS)) {
|
|
if (!debug_locks_off_graph_unlock())
|
|
return 0;
|
|
|
|
print_lockdep_off("BUG: MAX_LOCKDEP_CHAINS too low!");
|
|
dump_stack();
|
|
return 0;
|
|
}
|
|
chain = lock_chains + nr_lock_chains++;
|
|
chain->chain_key = chain_key;
|
|
chain->irq_context = hlock->irq_context;
|
|
i = get_first_held_lock(curr, hlock);
|
|
chain->depth = curr->lockdep_depth + 1 - i;
|
|
|
|
BUILD_BUG_ON((1UL << 24) <= ARRAY_SIZE(chain_hlocks));
|
|
BUILD_BUG_ON((1UL << 6) <= ARRAY_SIZE(curr->held_locks));
|
|
BUILD_BUG_ON((1UL << 8*sizeof(chain_hlocks[0])) <= ARRAY_SIZE(lock_classes));
|
|
|
|
if (likely(nr_chain_hlocks + chain->depth <= MAX_LOCKDEP_CHAIN_HLOCKS)) {
|
|
chain->base = nr_chain_hlocks;
|
|
for (j = 0; j < chain->depth - 1; j++, i++) {
|
|
int lock_id = curr->held_locks[i].class_idx - 1;
|
|
chain_hlocks[chain->base + j] = lock_id;
|
|
}
|
|
chain_hlocks[chain->base + j] = class - lock_classes;
|
|
}
|
|
|
|
if (nr_chain_hlocks < MAX_LOCKDEP_CHAIN_HLOCKS)
|
|
nr_chain_hlocks += chain->depth;
|
|
|
|
#ifdef CONFIG_DEBUG_LOCKDEP
|
|
/*
|
|
* Important for check_no_collision().
|
|
*/
|
|
if (unlikely(nr_chain_hlocks > MAX_LOCKDEP_CHAIN_HLOCKS)) {
|
|
if (!debug_locks_off_graph_unlock())
|
|
return 0;
|
|
|
|
print_lockdep_off("BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!");
|
|
dump_stack();
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
hlist_add_head_rcu(&chain->entry, hash_head);
|
|
debug_atomic_inc(chain_lookup_misses);
|
|
inc_chains();
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Look up a dependency chain.
|
|
*/
|
|
static inline struct lock_chain *lookup_chain_cache(u64 chain_key)
|
|
{
|
|
struct hlist_head *hash_head = chainhashentry(chain_key);
|
|
struct lock_chain *chain;
|
|
|
|
/*
|
|
* We can walk it lock-free, because entries only get added
|
|
* to the hash:
|
|
*/
|
|
hlist_for_each_entry_rcu(chain, hash_head, entry) {
|
|
if (chain->chain_key == chain_key) {
|
|
debug_atomic_inc(chain_lookup_hits);
|
|
return chain;
|
|
}
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* If the key is not present yet in dependency chain cache then
|
|
* add it and return 1 - in this case the new dependency chain is
|
|
* validated. If the key is already hashed, return 0.
|
|
* (On return with 1 graph_lock is held.)
|
|
*/
|
|
static inline int lookup_chain_cache_add(struct task_struct *curr,
|
|
struct held_lock *hlock,
|
|
u64 chain_key)
|
|
{
|
|
struct lock_class *class = hlock_class(hlock);
|
|
struct lock_chain *chain = lookup_chain_cache(chain_key);
|
|
|
|
if (chain) {
|
|
cache_hit:
|
|
if (!check_no_collision(curr, hlock, chain))
|
|
return 0;
|
|
|
|
if (very_verbose(class)) {
|
|
printk("\nhash chain already cached, key: "
|
|
"%016Lx tail class: [%p] %s\n",
|
|
(unsigned long long)chain_key,
|
|
class->key, class->name);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
if (very_verbose(class)) {
|
|
printk("\nnew hash chain, key: %016Lx tail class: [%p] %s\n",
|
|
(unsigned long long)chain_key, class->key, class->name);
|
|
}
|
|
|
|
if (!graph_lock())
|
|
return 0;
|
|
|
|
/*
|
|
* We have to walk the chain again locked - to avoid duplicates:
|
|
*/
|
|
chain = lookup_chain_cache(chain_key);
|
|
if (chain) {
|
|
graph_unlock();
|
|
goto cache_hit;
|
|
}
|
|
|
|
if (!add_chain_cache(curr, hlock, chain_key))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int validate_chain(struct task_struct *curr, struct lockdep_map *lock,
|
|
struct held_lock *hlock, int chain_head, u64 chain_key)
|
|
{
|
|
/*
|
|
* Trylock needs to maintain the stack of held locks, but it
|
|
* does not add new dependencies, because trylock can be done
|
|
* in any order.
|
|
*
|
|
* We look up the chain_key and do the O(N^2) check and update of
|
|
* the dependencies only if this is a new dependency chain.
|
|
* (If lookup_chain_cache_add() return with 1 it acquires
|
|
* graph_lock for us)
|
|
*/
|
|
if (!hlock->trylock && hlock->check &&
|
|
lookup_chain_cache_add(curr, hlock, chain_key)) {
|
|
/*
|
|
* Check whether last held lock:
|
|
*
|
|
* - is irq-safe, if this lock is irq-unsafe
|
|
* - is softirq-safe, if this lock is hardirq-unsafe
|
|
*
|
|
* And check whether the new lock's dependency graph
|
|
* could lead back to the previous lock.
|
|
*
|
|
* any of these scenarios could lead to a deadlock. If
|
|
* All validations
|
|
*/
|
|
int ret = check_deadlock(curr, hlock, lock, hlock->read);
|
|
|
|
if (!ret)
|
|
return 0;
|
|
/*
|
|
* Mark recursive read, as we jump over it when
|
|
* building dependencies (just like we jump over
|
|
* trylock entries):
|
|
*/
|
|
if (ret == 2)
|
|
hlock->read = 2;
|
|
/*
|
|
* Add dependency only if this lock is not the head
|
|
* of the chain, and if it's not a secondary read-lock:
|
|
*/
|
|
if (!chain_head && ret != 2) {
|
|
if (!check_prevs_add(curr, hlock))
|
|
return 0;
|
|
}
|
|
|
|
graph_unlock();
|
|
} else {
|
|
/* after lookup_chain_cache_add(): */
|
|
if (unlikely(!debug_locks))
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
#else
|
|
static inline int validate_chain(struct task_struct *curr,
|
|
struct lockdep_map *lock, struct held_lock *hlock,
|
|
int chain_head, u64 chain_key)
|
|
{
|
|
return 1;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* We are building curr_chain_key incrementally, so double-check
|
|
* it from scratch, to make sure that it's done correctly:
|
|
*/
|
|
static void check_chain_key(struct task_struct *curr)
|
|
{
|
|
#ifdef CONFIG_DEBUG_LOCKDEP
|
|
struct held_lock *hlock, *prev_hlock = NULL;
|
|
unsigned int i;
|
|
u64 chain_key = 0;
|
|
|
|
for (i = 0; i < curr->lockdep_depth; i++) {
|
|
hlock = curr->held_locks + i;
|
|
if (chain_key != hlock->prev_chain_key) {
|
|
debug_locks_off();
|
|
/*
|
|
* We got mighty confused, our chain keys don't match
|
|
* with what we expect, someone trample on our task state?
|
|
*/
|
|
WARN(1, "hm#1, depth: %u [%u], %016Lx != %016Lx\n",
|
|
curr->lockdep_depth, i,
|
|
(unsigned long long)chain_key,
|
|
(unsigned long long)hlock->prev_chain_key);
|
|
return;
|
|
}
|
|
/*
|
|
* Whoops ran out of static storage again?
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(hlock->class_idx > MAX_LOCKDEP_KEYS))
|
|
return;
|
|
|
|
if (prev_hlock && (prev_hlock->irq_context !=
|
|
hlock->irq_context))
|
|
chain_key = 0;
|
|
chain_key = iterate_chain_key(chain_key, hlock->class_idx);
|
|
prev_hlock = hlock;
|
|
}
|
|
if (chain_key != curr->curr_chain_key) {
|
|
debug_locks_off();
|
|
/*
|
|
* More smoking hash instead of calculating it, damn see these
|
|
* numbers float.. I bet that a pink elephant stepped on my memory.
|
|
*/
|
|
WARN(1, "hm#2, depth: %u [%u], %016Lx != %016Lx\n",
|
|
curr->lockdep_depth, i,
|
|
(unsigned long long)chain_key,
|
|
(unsigned long long)curr->curr_chain_key);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
static void
|
|
print_usage_bug_scenario(struct held_lock *lock)
|
|
{
|
|
struct lock_class *class = hlock_class(lock);
|
|
|
|
printk(" Possible unsafe locking scenario:\n\n");
|
|
printk(" CPU0\n");
|
|
printk(" ----\n");
|
|
printk(" lock(");
|
|
__print_lock_name(class);
|
|
printk(KERN_CONT ");\n");
|
|
printk(" <Interrupt>\n");
|
|
printk(" lock(");
|
|
__print_lock_name(class);
|
|
printk(KERN_CONT ");\n");
|
|
printk("\n *** DEADLOCK ***\n\n");
|
|
}
|
|
|
|
static int
|
|
print_usage_bug(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
|
|
{
|
|
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
|
|
return 0;
|
|
|
|
pr_warn("\n");
|
|
pr_warn("================================\n");
|
|
pr_warn("WARNING: inconsistent lock state\n");
|
|
print_kernel_ident();
|
|
pr_warn("--------------------------------\n");
|
|
|
|
pr_warn("inconsistent {%s} -> {%s} usage.\n",
|
|
usage_str[prev_bit], usage_str[new_bit]);
|
|
|
|
pr_warn("%s/%d [HC%u[%lu]:SC%u[%lu]:HE%u:SE%u] takes:\n",
|
|
curr->comm, task_pid_nr(curr),
|
|
trace_hardirq_context(curr), hardirq_count() >> HARDIRQ_SHIFT,
|
|
trace_softirq_context(curr), softirq_count() >> SOFTIRQ_SHIFT,
|
|
trace_hardirqs_enabled(curr),
|
|
trace_softirqs_enabled(curr));
|
|
print_lock(this);
|
|
|
|
pr_warn("{%s} state was registered at:\n", usage_str[prev_bit]);
|
|
print_stack_trace(hlock_class(this)->usage_traces + prev_bit, 1);
|
|
|
|
print_irqtrace_events(curr);
|
|
pr_warn("\nother info that might help us debug this:\n");
|
|
print_usage_bug_scenario(this);
|
|
|
|
lockdep_print_held_locks(curr);
|
|
|
|
pr_warn("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Print out an error if an invalid bit is set:
|
|
*/
|
|
static inline int
|
|
valid_state(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
|
|
{
|
|
if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit)))
|
|
return print_usage_bug(curr, this, bad_bit, new_bit);
|
|
return 1;
|
|
}
|
|
|
|
static int mark_lock(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit new_bit);
|
|
|
|
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
|
|
|
|
/*
|
|
* print irq inversion bug:
|
|
*/
|
|
static int
|
|
print_irq_inversion_bug(struct task_struct *curr,
|
|
struct lock_list *root, struct lock_list *other,
|
|
struct held_lock *this, int forwards,
|
|
const char *irqclass)
|
|
{
|
|
struct lock_list *entry = other;
|
|
struct lock_list *middle = NULL;
|
|
int depth;
|
|
|
|
if (!debug_locks_off_graph_unlock() || debug_locks_silent)
|
|
return 0;
|
|
|
|
pr_warn("\n");
|
|
pr_warn("========================================================\n");
|
|
pr_warn("WARNING: possible irq lock inversion dependency detected\n");
|
|
print_kernel_ident();
|
|
pr_warn("--------------------------------------------------------\n");
|
|
pr_warn("%s/%d just changed the state of lock:\n",
|
|
curr->comm, task_pid_nr(curr));
|
|
print_lock(this);
|
|
if (forwards)
|
|
pr_warn("but this lock took another, %s-unsafe lock in the past:\n", irqclass);
|
|
else
|
|
pr_warn("but this lock was taken by another, %s-safe lock in the past:\n", irqclass);
|
|
print_lock_name(other->class);
|
|
pr_warn("\n\nand interrupts could create inverse lock ordering between them.\n\n");
|
|
|
|
pr_warn("\nother info that might help us debug this:\n");
|
|
|
|
/* Find a middle lock (if one exists) */
|
|
depth = get_lock_depth(other);
|
|
do {
|
|
if (depth == 0 && (entry != root)) {
|
|
pr_warn("lockdep:%s bad path found in chain graph\n", __func__);
|
|
break;
|
|
}
|
|
middle = entry;
|
|
entry = get_lock_parent(entry);
|
|
depth--;
|
|
} while (entry && entry != root && (depth >= 0));
|
|
if (forwards)
|
|
print_irq_lock_scenario(root, other,
|
|
middle ? middle->class : root->class, other->class);
|
|
else
|
|
print_irq_lock_scenario(other, root,
|
|
middle ? middle->class : other->class, root->class);
|
|
|
|
lockdep_print_held_locks(curr);
|
|
|
|
pr_warn("\nthe shortest dependencies between 2nd lock and 1st lock:\n");
|
|
if (!save_trace(&root->trace))
|
|
return 0;
|
|
print_shortest_lock_dependencies(other, root);
|
|
|
|
pr_warn("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Prove that in the forwards-direction subgraph starting at <this>
|
|
* there is no lock matching <mask>:
|
|
*/
|
|
static int
|
|
check_usage_forwards(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit bit, const char *irqclass)
|
|
{
|
|
int ret;
|
|
struct lock_list root;
|
|
struct lock_list *uninitialized_var(target_entry);
|
|
|
|
root.parent = NULL;
|
|
root.class = hlock_class(this);
|
|
ret = find_usage_forwards(&root, bit, &target_entry);
|
|
if (ret < 0)
|
|
return print_bfs_bug(ret);
|
|
if (ret == 1)
|
|
return ret;
|
|
|
|
return print_irq_inversion_bug(curr, &root, target_entry,
|
|
this, 1, irqclass);
|
|
}
|
|
|
|
/*
|
|
* Prove that in the backwards-direction subgraph starting at <this>
|
|
* there is no lock matching <mask>:
|
|
*/
|
|
static int
|
|
check_usage_backwards(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit bit, const char *irqclass)
|
|
{
|
|
int ret;
|
|
struct lock_list root;
|
|
struct lock_list *uninitialized_var(target_entry);
|
|
|
|
root.parent = NULL;
|
|
root.class = hlock_class(this);
|
|
ret = find_usage_backwards(&root, bit, &target_entry);
|
|
if (ret < 0)
|
|
return print_bfs_bug(ret);
|
|
if (ret == 1)
|
|
return ret;
|
|
|
|
return print_irq_inversion_bug(curr, &root, target_entry,
|
|
this, 0, irqclass);
|
|
}
|
|
|
|
void print_irqtrace_events(struct task_struct *curr)
|
|
{
|
|
printk("irq event stamp: %u\n", curr->irq_events);
|
|
printk("hardirqs last enabled at (%u): [<%p>] %pS\n",
|
|
curr->hardirq_enable_event, (void *)curr->hardirq_enable_ip,
|
|
(void *)curr->hardirq_enable_ip);
|
|
printk("hardirqs last disabled at (%u): [<%p>] %pS\n",
|
|
curr->hardirq_disable_event, (void *)curr->hardirq_disable_ip,
|
|
(void *)curr->hardirq_disable_ip);
|
|
printk("softirqs last enabled at (%u): [<%p>] %pS\n",
|
|
curr->softirq_enable_event, (void *)curr->softirq_enable_ip,
|
|
(void *)curr->softirq_enable_ip);
|
|
printk("softirqs last disabled at (%u): [<%p>] %pS\n",
|
|
curr->softirq_disable_event, (void *)curr->softirq_disable_ip,
|
|
(void *)curr->softirq_disable_ip);
|
|
}
|
|
|
|
static int HARDIRQ_verbose(struct lock_class *class)
|
|
{
|
|
#if HARDIRQ_VERBOSE
|
|
return class_filter(class);
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
static int SOFTIRQ_verbose(struct lock_class *class)
|
|
{
|
|
#if SOFTIRQ_VERBOSE
|
|
return class_filter(class);
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
#define STRICT_READ_CHECKS 1
|
|
|
|
static int (*state_verbose_f[])(struct lock_class *class) = {
|
|
#define LOCKDEP_STATE(__STATE) \
|
|
__STATE##_verbose,
|
|
#include "lockdep_states.h"
|
|
#undef LOCKDEP_STATE
|
|
};
|
|
|
|
static inline int state_verbose(enum lock_usage_bit bit,
|
|
struct lock_class *class)
|
|
{
|
|
return state_verbose_f[bit >> 2](class);
|
|
}
|
|
|
|
typedef int (*check_usage_f)(struct task_struct *, struct held_lock *,
|
|
enum lock_usage_bit bit, const char *name);
|
|
|
|
static int
|
|
mark_lock_irq(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit new_bit)
|
|
{
|
|
int excl_bit = exclusive_bit(new_bit);
|
|
int read = new_bit & 1;
|
|
int dir = new_bit & 2;
|
|
|
|
/*
|
|
* mark USED_IN has to look forwards -- to ensure no dependency
|
|
* has ENABLED state, which would allow recursion deadlocks.
|
|
*
|
|
* mark ENABLED has to look backwards -- to ensure no dependee
|
|
* has USED_IN state, which, again, would allow recursion deadlocks.
|
|
*/
|
|
check_usage_f usage = dir ?
|
|
check_usage_backwards : check_usage_forwards;
|
|
|
|
/*
|
|
* Validate that this particular lock does not have conflicting
|
|
* usage states.
|
|
*/
|
|
if (!valid_state(curr, this, new_bit, excl_bit))
|
|
return 0;
|
|
|
|
/*
|
|
* Validate that the lock dependencies don't have conflicting usage
|
|
* states.
|
|
*/
|
|
if ((!read || !dir || STRICT_READ_CHECKS) &&
|
|
!usage(curr, this, excl_bit, state_name(new_bit & ~1)))
|
|
return 0;
|
|
|
|
/*
|
|
* Check for read in write conflicts
|
|
*/
|
|
if (!read) {
|
|
if (!valid_state(curr, this, new_bit, excl_bit + 1))
|
|
return 0;
|
|
|
|
if (STRICT_READ_CHECKS &&
|
|
!usage(curr, this, excl_bit + 1,
|
|
state_name(new_bit + 1)))
|
|
return 0;
|
|
}
|
|
|
|
if (state_verbose(new_bit, hlock_class(this)))
|
|
return 2;
|
|
|
|
return 1;
|
|
}
|
|
|
|
enum mark_type {
|
|
#define LOCKDEP_STATE(__STATE) __STATE,
|
|
#include "lockdep_states.h"
|
|
#undef LOCKDEP_STATE
|
|
};
|
|
|
|
/*
|
|
* Mark all held locks with a usage bit:
|
|
*/
|
|
static int
|
|
mark_held_locks(struct task_struct *curr, enum mark_type mark)
|
|
{
|
|
enum lock_usage_bit usage_bit;
|
|
struct held_lock *hlock;
|
|
int i;
|
|
|
|
for (i = 0; i < curr->lockdep_depth; i++) {
|
|
hlock = curr->held_locks + i;
|
|
|
|
usage_bit = 2 + (mark << 2); /* ENABLED */
|
|
if (hlock->read)
|
|
usage_bit += 1; /* READ */
|
|
|
|
BUG_ON(usage_bit >= LOCK_USAGE_STATES);
|
|
|
|
if (!hlock->check)
|
|
continue;
|
|
|
|
if (!mark_lock(curr, hlock, usage_bit))
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Hardirqs will be enabled:
|
|
*/
|
|
static void __trace_hardirqs_on_caller(unsigned long ip)
|
|
{
|
|
struct task_struct *curr = current;
|
|
|
|
/* we'll do an OFF -> ON transition: */
|
|
curr->hardirqs_enabled = 1;
|
|
|
|
/*
|
|
* We are going to turn hardirqs on, so set the
|
|
* usage bit for all held locks:
|
|
*/
|
|
if (!mark_held_locks(curr, HARDIRQ))
|
|
return;
|
|
/*
|
|
* If we have softirqs enabled, then set the usage
|
|
* bit for all held locks. (disabled hardirqs prevented
|
|
* this bit from being set before)
|
|
*/
|
|
if (curr->softirqs_enabled)
|
|
if (!mark_held_locks(curr, SOFTIRQ))
|
|
return;
|
|
|
|
curr->hardirq_enable_ip = ip;
|
|
curr->hardirq_enable_event = ++curr->irq_events;
|
|
debug_atomic_inc(hardirqs_on_events);
|
|
}
|
|
|
|
__visible void trace_hardirqs_on_caller(unsigned long ip)
|
|
{
|
|
time_hardirqs_on(CALLER_ADDR0, ip);
|
|
|
|
if (unlikely(!debug_locks || current->lockdep_recursion))
|
|
return;
|
|
|
|
if (unlikely(current->hardirqs_enabled)) {
|
|
/*
|
|
* Neither irq nor preemption are disabled here
|
|
* so this is racy by nature but losing one hit
|
|
* in a stat is not a big deal.
|
|
*/
|
|
__debug_atomic_inc(redundant_hardirqs_on);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* We're enabling irqs and according to our state above irqs weren't
|
|
* already enabled, yet we find the hardware thinks they are in fact
|
|
* enabled.. someone messed up their IRQ state tracing.
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return;
|
|
|
|
/*
|
|
* See the fine text that goes along with this variable definition.
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(unlikely(early_boot_irqs_disabled)))
|
|
return;
|
|
|
|
/*
|
|
* Can't allow enabling interrupts while in an interrupt handler,
|
|
* that's general bad form and such. Recursion, limited stack etc..
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(current->hardirq_context))
|
|
return;
|
|
|
|
current->lockdep_recursion = 1;
|
|
__trace_hardirqs_on_caller(ip);
|
|
current->lockdep_recursion = 0;
|
|
}
|
|
EXPORT_SYMBOL(trace_hardirqs_on_caller);
|
|
|
|
void trace_hardirqs_on(void)
|
|
{
|
|
trace_hardirqs_on_caller(CALLER_ADDR0);
|
|
}
|
|
EXPORT_SYMBOL(trace_hardirqs_on);
|
|
|
|
/*
|
|
* Hardirqs were disabled:
|
|
*/
|
|
__visible void trace_hardirqs_off_caller(unsigned long ip)
|
|
{
|
|
struct task_struct *curr = current;
|
|
|
|
time_hardirqs_off(CALLER_ADDR0, ip);
|
|
|
|
if (unlikely(!debug_locks || current->lockdep_recursion))
|
|
return;
|
|
|
|
/*
|
|
* So we're supposed to get called after you mask local IRQs, but for
|
|
* some reason the hardware doesn't quite think you did a proper job.
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return;
|
|
|
|
if (curr->hardirqs_enabled) {
|
|
/*
|
|
* We have done an ON -> OFF transition:
|
|
*/
|
|
curr->hardirqs_enabled = 0;
|
|
curr->hardirq_disable_ip = ip;
|
|
curr->hardirq_disable_event = ++curr->irq_events;
|
|
debug_atomic_inc(hardirqs_off_events);
|
|
} else
|
|
debug_atomic_inc(redundant_hardirqs_off);
|
|
}
|
|
EXPORT_SYMBOL(trace_hardirqs_off_caller);
|
|
|
|
void trace_hardirqs_off(void)
|
|
{
|
|
trace_hardirqs_off_caller(CALLER_ADDR0);
|
|
}
|
|
EXPORT_SYMBOL(trace_hardirqs_off);
|
|
|
|
/*
|
|
* Softirqs will be enabled:
|
|
*/
|
|
void trace_softirqs_on(unsigned long ip)
|
|
{
|
|
struct task_struct *curr = current;
|
|
|
|
if (unlikely(!debug_locks || current->lockdep_recursion))
|
|
return;
|
|
|
|
/*
|
|
* We fancy IRQs being disabled here, see softirq.c, avoids
|
|
* funny state and nesting things.
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return;
|
|
|
|
if (curr->softirqs_enabled) {
|
|
debug_atomic_inc(redundant_softirqs_on);
|
|
return;
|
|
}
|
|
|
|
current->lockdep_recursion = 1;
|
|
/*
|
|
* We'll do an OFF -> ON transition:
|
|
*/
|
|
curr->softirqs_enabled = 1;
|
|
curr->softirq_enable_ip = ip;
|
|
curr->softirq_enable_event = ++curr->irq_events;
|
|
debug_atomic_inc(softirqs_on_events);
|
|
/*
|
|
* We are going to turn softirqs on, so set the
|
|
* usage bit for all held locks, if hardirqs are
|
|
* enabled too:
|
|
*/
|
|
if (curr->hardirqs_enabled)
|
|
mark_held_locks(curr, SOFTIRQ);
|
|
current->lockdep_recursion = 0;
|
|
}
|
|
|
|
/*
|
|
* Softirqs were disabled:
|
|
*/
|
|
void trace_softirqs_off(unsigned long ip)
|
|
{
|
|
struct task_struct *curr = current;
|
|
|
|
if (unlikely(!debug_locks || current->lockdep_recursion))
|
|
return;
|
|
|
|
/*
|
|
* We fancy IRQs being disabled here, see softirq.c
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return;
|
|
|
|
if (curr->softirqs_enabled) {
|
|
/*
|
|
* We have done an ON -> OFF transition:
|
|
*/
|
|
curr->softirqs_enabled = 0;
|
|
curr->softirq_disable_ip = ip;
|
|
curr->softirq_disable_event = ++curr->irq_events;
|
|
debug_atomic_inc(softirqs_off_events);
|
|
/*
|
|
* Whoops, we wanted softirqs off, so why aren't they?
|
|
*/
|
|
DEBUG_LOCKS_WARN_ON(!softirq_count());
|
|
} else
|
|
debug_atomic_inc(redundant_softirqs_off);
|
|
}
|
|
|
|
static int mark_irqflags(struct task_struct *curr, struct held_lock *hlock)
|
|
{
|
|
/*
|
|
* If non-trylock use in a hardirq or softirq context, then
|
|
* mark the lock as used in these contexts:
|
|
*/
|
|
if (!hlock->trylock) {
|
|
if (hlock->read) {
|
|
if (curr->hardirq_context)
|
|
if (!mark_lock(curr, hlock,
|
|
LOCK_USED_IN_HARDIRQ_READ))
|
|
return 0;
|
|
if (curr->softirq_context)
|
|
if (!mark_lock(curr, hlock,
|
|
LOCK_USED_IN_SOFTIRQ_READ))
|
|
return 0;
|
|
} else {
|
|
if (curr->hardirq_context)
|
|
if (!mark_lock(curr, hlock, LOCK_USED_IN_HARDIRQ))
|
|
return 0;
|
|
if (curr->softirq_context)
|
|
if (!mark_lock(curr, hlock, LOCK_USED_IN_SOFTIRQ))
|
|
return 0;
|
|
}
|
|
}
|
|
if (!hlock->hardirqs_off) {
|
|
if (hlock->read) {
|
|
if (!mark_lock(curr, hlock,
|
|
LOCK_ENABLED_HARDIRQ_READ))
|
|
return 0;
|
|
if (curr->softirqs_enabled)
|
|
if (!mark_lock(curr, hlock,
|
|
LOCK_ENABLED_SOFTIRQ_READ))
|
|
return 0;
|
|
} else {
|
|
if (!mark_lock(curr, hlock,
|
|
LOCK_ENABLED_HARDIRQ))
|
|
return 0;
|
|
if (curr->softirqs_enabled)
|
|
if (!mark_lock(curr, hlock,
|
|
LOCK_ENABLED_SOFTIRQ))
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
static inline unsigned int task_irq_context(struct task_struct *task)
|
|
{
|
|
return 2 * !!task->hardirq_context + !!task->softirq_context;
|
|
}
|
|
|
|
static int separate_irq_context(struct task_struct *curr,
|
|
struct held_lock *hlock)
|
|
{
|
|
unsigned int depth = curr->lockdep_depth;
|
|
|
|
/*
|
|
* Keep track of points where we cross into an interrupt context:
|
|
*/
|
|
if (depth) {
|
|
struct held_lock *prev_hlock;
|
|
|
|
prev_hlock = curr->held_locks + depth-1;
|
|
/*
|
|
* If we cross into another context, reset the
|
|
* hash key (this also prevents the checking and the
|
|
* adding of the dependency to 'prev'):
|
|
*/
|
|
if (prev_hlock->irq_context != hlock->irq_context)
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
|
|
|
|
static inline
|
|
int mark_lock_irq(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit new_bit)
|
|
{
|
|
WARN_ON(1); /* Impossible innit? when we don't have TRACE_IRQFLAG */
|
|
return 1;
|
|
}
|
|
|
|
static inline int mark_irqflags(struct task_struct *curr,
|
|
struct held_lock *hlock)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
static inline unsigned int task_irq_context(struct task_struct *task)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline int separate_irq_context(struct task_struct *curr,
|
|
struct held_lock *hlock)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
|
|
|
|
/*
|
|
* Mark a lock with a usage bit, and validate the state transition:
|
|
*/
|
|
static int mark_lock(struct task_struct *curr, struct held_lock *this,
|
|
enum lock_usage_bit new_bit)
|
|
{
|
|
unsigned int new_mask = 1 << new_bit, ret = 1;
|
|
|
|
/*
|
|
* If already set then do not dirty the cacheline,
|
|
* nor do any checks:
|
|
*/
|
|
if (likely(hlock_class(this)->usage_mask & new_mask))
|
|
return 1;
|
|
|
|
if (!graph_lock())
|
|
return 0;
|
|
/*
|
|
* Make sure we didn't race:
|
|
*/
|
|
if (unlikely(hlock_class(this)->usage_mask & new_mask)) {
|
|
graph_unlock();
|
|
return 1;
|
|
}
|
|
|
|
hlock_class(this)->usage_mask |= new_mask;
|
|
|
|
if (!save_trace(hlock_class(this)->usage_traces + new_bit))
|
|
return 0;
|
|
|
|
switch (new_bit) {
|
|
#define LOCKDEP_STATE(__STATE) \
|
|
case LOCK_USED_IN_##__STATE: \
|
|
case LOCK_USED_IN_##__STATE##_READ: \
|
|
case LOCK_ENABLED_##__STATE: \
|
|
case LOCK_ENABLED_##__STATE##_READ:
|
|
#include "lockdep_states.h"
|
|
#undef LOCKDEP_STATE
|
|
ret = mark_lock_irq(curr, this, new_bit);
|
|
if (!ret)
|
|
return 0;
|
|
break;
|
|
case LOCK_USED:
|
|
debug_atomic_dec(nr_unused_locks);
|
|
break;
|
|
default:
|
|
if (!debug_locks_off_graph_unlock())
|
|
return 0;
|
|
WARN_ON(1);
|
|
return 0;
|
|
}
|
|
|
|
graph_unlock();
|
|
|
|
/*
|
|
* We must printk outside of the graph_lock:
|
|
*/
|
|
if (ret == 2) {
|
|
printk("\nmarked lock as {%s}:\n", usage_str[new_bit]);
|
|
print_lock(this);
|
|
print_irqtrace_events(curr);
|
|
dump_stack();
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Initialize a lock instance's lock-class mapping info:
|
|
*/
|
|
static void __lockdep_init_map(struct lockdep_map *lock, const char *name,
|
|
struct lock_class_key *key, int subclass)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < NR_LOCKDEP_CACHING_CLASSES; i++)
|
|
lock->class_cache[i] = NULL;
|
|
|
|
#ifdef CONFIG_LOCK_STAT
|
|
lock->cpu = raw_smp_processor_id();
|
|
#endif
|
|
|
|
/*
|
|
* Can't be having no nameless bastards around this place!
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!name)) {
|
|
lock->name = "NULL";
|
|
return;
|
|
}
|
|
|
|
lock->name = name;
|
|
|
|
/*
|
|
* No key, no joy, we need to hash something.
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!key))
|
|
return;
|
|
/*
|
|
* Sanity check, the lock-class key must be persistent:
|
|
*/
|
|
if (!static_obj(key)) {
|
|
printk("BUG: key %p not in .data!\n", key);
|
|
/*
|
|
* What it says above ^^^^^, I suggest you read it.
|
|
*/
|
|
DEBUG_LOCKS_WARN_ON(1);
|
|
return;
|
|
}
|
|
lock->key = key;
|
|
|
|
if (unlikely(!debug_locks))
|
|
return;
|
|
|
|
if (subclass) {
|
|
unsigned long flags;
|
|
|
|
if (DEBUG_LOCKS_WARN_ON(current->lockdep_recursion))
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
current->lockdep_recursion = 1;
|
|
register_lock_class(lock, subclass, 1);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
}
|
|
|
|
void lockdep_init_map(struct lockdep_map *lock, const char *name,
|
|
struct lock_class_key *key, int subclass)
|
|
{
|
|
cross_init(lock, 0);
|
|
__lockdep_init_map(lock, name, key, subclass);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lockdep_init_map);
|
|
|
|
#ifdef CONFIG_LOCKDEP_CROSSRELEASE
|
|
void lockdep_init_map_crosslock(struct lockdep_map *lock, const char *name,
|
|
struct lock_class_key *key, int subclass)
|
|
{
|
|
cross_init(lock, 1);
|
|
__lockdep_init_map(lock, name, key, subclass);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lockdep_init_map_crosslock);
|
|
#endif
|
|
|
|
struct lock_class_key __lockdep_no_validate__;
|
|
EXPORT_SYMBOL_GPL(__lockdep_no_validate__);
|
|
|
|
static int
|
|
print_lock_nested_lock_not_held(struct task_struct *curr,
|
|
struct held_lock *hlock,
|
|
unsigned long ip)
|
|
{
|
|
if (!debug_locks_off())
|
|
return 0;
|
|
if (debug_locks_silent)
|
|
return 0;
|
|
|
|
pr_warn("\n");
|
|
pr_warn("==================================\n");
|
|
pr_warn("WARNING: Nested lock was not taken\n");
|
|
print_kernel_ident();
|
|
pr_warn("----------------------------------\n");
|
|
|
|
pr_warn("%s/%d is trying to lock:\n", curr->comm, task_pid_nr(curr));
|
|
print_lock(hlock);
|
|
|
|
pr_warn("\nbut this task is not holding:\n");
|
|
pr_warn("%s\n", hlock->nest_lock->name);
|
|
|
|
pr_warn("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
pr_warn("\nother info that might help us debug this:\n");
|
|
lockdep_print_held_locks(curr);
|
|
|
|
pr_warn("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int __lock_is_held(struct lockdep_map *lock, int read);
|
|
|
|
/*
|
|
* This gets called for every mutex_lock*()/spin_lock*() operation.
|
|
* We maintain the dependency maps and validate the locking attempt:
|
|
*/
|
|
static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
|
|
int trylock, int read, int check, int hardirqs_off,
|
|
struct lockdep_map *nest_lock, unsigned long ip,
|
|
int references, int pin_count)
|
|
{
|
|
struct task_struct *curr = current;
|
|
struct lock_class *class = NULL;
|
|
struct held_lock *hlock;
|
|
unsigned int depth;
|
|
int chain_head = 0;
|
|
int class_idx;
|
|
u64 chain_key;
|
|
int ret;
|
|
|
|
if (unlikely(!debug_locks))
|
|
return 0;
|
|
|
|
/*
|
|
* Lockdep should run with IRQs disabled, otherwise we could
|
|
* get an interrupt which would want to take locks, which would
|
|
* end up in lockdep and have you got a head-ache already?
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
|
|
return 0;
|
|
|
|
if (!prove_locking || lock->key == &__lockdep_no_validate__)
|
|
check = 0;
|
|
|
|
if (subclass < NR_LOCKDEP_CACHING_CLASSES)
|
|
class = lock->class_cache[subclass];
|
|
/*
|
|
* Not cached?
|
|
*/
|
|
if (unlikely(!class)) {
|
|
class = register_lock_class(lock, subclass, 0);
|
|
if (!class)
|
|
return 0;
|
|
}
|
|
atomic_inc((atomic_t *)&class->ops);
|
|
if (very_verbose(class)) {
|
|
printk("\nacquire class [%p] %s", class->key, class->name);
|
|
if (class->name_version > 1)
|
|
printk(KERN_CONT "#%d", class->name_version);
|
|
printk(KERN_CONT "\n");
|
|
dump_stack();
|
|
}
|
|
|
|
/*
|
|
* Add the lock to the list of currently held locks.
|
|
* (we dont increase the depth just yet, up until the
|
|
* dependency checks are done)
|
|
*/
|
|
depth = curr->lockdep_depth;
|
|
/*
|
|
* Ran out of static storage for our per-task lock stack again have we?
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(depth >= MAX_LOCK_DEPTH))
|
|
return 0;
|
|
|
|
class_idx = class - lock_classes + 1;
|
|
|
|
/* TODO: nest_lock is not implemented for crosslock yet. */
|
|
if (depth && !cross_lock(lock)) {
|
|
hlock = curr->held_locks + depth - 1;
|
|
if (hlock->class_idx == class_idx && nest_lock) {
|
|
if (hlock->references) {
|
|
/*
|
|
* Check: unsigned int references:12, overflow.
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(hlock->references == (1 << 12)-1))
|
|
return 0;
|
|
|
|
hlock->references++;
|
|
} else {
|
|
hlock->references = 2;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
hlock = curr->held_locks + depth;
|
|
/*
|
|
* Plain impossible, we just registered it and checked it weren't no
|
|
* NULL like.. I bet this mushroom I ate was good!
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!class))
|
|
return 0;
|
|
hlock->class_idx = class_idx;
|
|
hlock->acquire_ip = ip;
|
|
hlock->instance = lock;
|
|
hlock->nest_lock = nest_lock;
|
|
hlock->irq_context = task_irq_context(curr);
|
|
hlock->trylock = trylock;
|
|
hlock->read = read;
|
|
hlock->check = check;
|
|
hlock->hardirqs_off = !!hardirqs_off;
|
|
hlock->references = references;
|
|
#ifdef CONFIG_LOCK_STAT
|
|
hlock->waittime_stamp = 0;
|
|
hlock->holdtime_stamp = lockstat_clock();
|
|
#endif
|
|
hlock->pin_count = pin_count;
|
|
|
|
if (check && !mark_irqflags(curr, hlock))
|
|
return 0;
|
|
|
|
/* mark it as used: */
|
|
if (!mark_lock(curr, hlock, LOCK_USED))
|
|
return 0;
|
|
|
|
/*
|
|
* Calculate the chain hash: it's the combined hash of all the
|
|
* lock keys along the dependency chain. We save the hash value
|
|
* at every step so that we can get the current hash easily
|
|
* after unlock. The chain hash is then used to cache dependency
|
|
* results.
|
|
*
|
|
* The 'key ID' is what is the most compact key value to drive
|
|
* the hash, not class->key.
|
|
*/
|
|
/*
|
|
* Whoops, we did it again.. ran straight out of our static allocation.
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(class_idx > MAX_LOCKDEP_KEYS))
|
|
return 0;
|
|
|
|
chain_key = curr->curr_chain_key;
|
|
if (!depth) {
|
|
/*
|
|
* How can we have a chain hash when we ain't got no keys?!
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(chain_key != 0))
|
|
return 0;
|
|
chain_head = 1;
|
|
}
|
|
|
|
hlock->prev_chain_key = chain_key;
|
|
if (separate_irq_context(curr, hlock)) {
|
|
chain_key = 0;
|
|
chain_head = 1;
|
|
}
|
|
chain_key = iterate_chain_key(chain_key, class_idx);
|
|
|
|
if (nest_lock && !__lock_is_held(nest_lock, -1))
|
|
return print_lock_nested_lock_not_held(curr, hlock, ip);
|
|
|
|
if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
|
|
return 0;
|
|
|
|
ret = lock_acquire_crosslock(hlock);
|
|
/*
|
|
* 2 means normal acquire operations are needed. Otherwise, it's
|
|
* ok just to return with '0:fail, 1:success'.
|
|
*/
|
|
if (ret != 2)
|
|
return ret;
|
|
|
|
curr->curr_chain_key = chain_key;
|
|
curr->lockdep_depth++;
|
|
check_chain_key(curr);
|
|
#ifdef CONFIG_DEBUG_LOCKDEP
|
|
if (unlikely(!debug_locks))
|
|
return 0;
|
|
#endif
|
|
if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {
|
|
debug_locks_off();
|
|
print_lockdep_off("BUG: MAX_LOCK_DEPTH too low!");
|
|
printk(KERN_DEBUG "depth: %i max: %lu!\n",
|
|
curr->lockdep_depth, MAX_LOCK_DEPTH);
|
|
|
|
lockdep_print_held_locks(current);
|
|
debug_show_all_locks();
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
if (unlikely(curr->lockdep_depth > max_lockdep_depth))
|
|
max_lockdep_depth = curr->lockdep_depth;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int
|
|
print_unlock_imbalance_bug(struct task_struct *curr, struct lockdep_map *lock,
|
|
unsigned long ip)
|
|
{
|
|
if (!debug_locks_off())
|
|
return 0;
|
|
if (debug_locks_silent)
|
|
return 0;
|
|
|
|
pr_warn("\n");
|
|
pr_warn("=====================================\n");
|
|
pr_warn("WARNING: bad unlock balance detected!\n");
|
|
print_kernel_ident();
|
|
pr_warn("-------------------------------------\n");
|
|
pr_warn("%s/%d is trying to release lock (",
|
|
curr->comm, task_pid_nr(curr));
|
|
print_lockdep_cache(lock);
|
|
pr_cont(") at:\n");
|
|
print_ip_sym(ip);
|
|
pr_warn("but there are no more locks to release!\n");
|
|
pr_warn("\nother info that might help us debug this:\n");
|
|
lockdep_print_held_locks(curr);
|
|
|
|
pr_warn("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int match_held_lock(struct held_lock *hlock, struct lockdep_map *lock)
|
|
{
|
|
if (hlock->instance == lock)
|
|
return 1;
|
|
|
|
if (hlock->references) {
|
|
struct lock_class *class = lock->class_cache[0];
|
|
|
|
if (!class)
|
|
class = look_up_lock_class(lock, 0);
|
|
|
|
/*
|
|
* If look_up_lock_class() failed to find a class, we're trying
|
|
* to test if we hold a lock that has never yet been acquired.
|
|
* Clearly if the lock hasn't been acquired _ever_, we're not
|
|
* holding it either, so report failure.
|
|
*/
|
|
if (IS_ERR_OR_NULL(class))
|
|
return 0;
|
|
|
|
/*
|
|
* References, but not a lock we're actually ref-counting?
|
|
* State got messed up, follow the sites that change ->references
|
|
* and try to make sense of it.
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!hlock->nest_lock))
|
|
return 0;
|
|
|
|
if (hlock->class_idx == class - lock_classes + 1)
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* @depth must not be zero */
|
|
static struct held_lock *find_held_lock(struct task_struct *curr,
|
|
struct lockdep_map *lock,
|
|
unsigned int depth, int *idx)
|
|
{
|
|
struct held_lock *ret, *hlock, *prev_hlock;
|
|
int i;
|
|
|
|
i = depth - 1;
|
|
hlock = curr->held_locks + i;
|
|
ret = hlock;
|
|
if (match_held_lock(hlock, lock))
|
|
goto out;
|
|
|
|
ret = NULL;
|
|
for (i--, prev_hlock = hlock--;
|
|
i >= 0;
|
|
i--, prev_hlock = hlock--) {
|
|
/*
|
|
* We must not cross into another context:
|
|
*/
|
|
if (prev_hlock->irq_context != hlock->irq_context) {
|
|
ret = NULL;
|
|
break;
|
|
}
|
|
if (match_held_lock(hlock, lock)) {
|
|
ret = hlock;
|
|
break;
|
|
}
|
|
}
|
|
|
|
out:
|
|
*idx = i;
|
|
return ret;
|
|
}
|
|
|
|
static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
|
|
int idx)
|
|
{
|
|
struct held_lock *hlock;
|
|
|
|
for (hlock = curr->held_locks + idx; idx < depth; idx++, hlock++) {
|
|
if (!__lock_acquire(hlock->instance,
|
|
hlock_class(hlock)->subclass,
|
|
hlock->trylock,
|
|
hlock->read, hlock->check,
|
|
hlock->hardirqs_off,
|
|
hlock->nest_lock, hlock->acquire_ip,
|
|
hlock->references, hlock->pin_count))
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int
|
|
__lock_set_class(struct lockdep_map *lock, const char *name,
|
|
struct lock_class_key *key, unsigned int subclass,
|
|
unsigned long ip)
|
|
{
|
|
struct task_struct *curr = current;
|
|
struct held_lock *hlock;
|
|
struct lock_class *class;
|
|
unsigned int depth;
|
|
int i;
|
|
|
|
depth = curr->lockdep_depth;
|
|
/*
|
|
* This function is about (re)setting the class of a held lock,
|
|
* yet we're not actually holding any locks. Naughty user!
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!depth))
|
|
return 0;
|
|
|
|
hlock = find_held_lock(curr, lock, depth, &i);
|
|
if (!hlock)
|
|
return print_unlock_imbalance_bug(curr, lock, ip);
|
|
|
|
lockdep_init_map(lock, name, key, 0);
|
|
class = register_lock_class(lock, subclass, 0);
|
|
hlock->class_idx = class - lock_classes + 1;
|
|
|
|
curr->lockdep_depth = i;
|
|
curr->curr_chain_key = hlock->prev_chain_key;
|
|
|
|
if (reacquire_held_locks(curr, depth, i))
|
|
return 0;
|
|
|
|
/*
|
|
* I took it apart and put it back together again, except now I have
|
|
* these 'spare' parts.. where shall I put them.
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip)
|
|
{
|
|
struct task_struct *curr = current;
|
|
struct held_lock *hlock;
|
|
unsigned int depth;
|
|
int i;
|
|
|
|
depth = curr->lockdep_depth;
|
|
/*
|
|
* This function is about (re)setting the class of a held lock,
|
|
* yet we're not actually holding any locks. Naughty user!
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!depth))
|
|
return 0;
|
|
|
|
hlock = find_held_lock(curr, lock, depth, &i);
|
|
if (!hlock)
|
|
return print_unlock_imbalance_bug(curr, lock, ip);
|
|
|
|
curr->lockdep_depth = i;
|
|
curr->curr_chain_key = hlock->prev_chain_key;
|
|
|
|
WARN(hlock->read, "downgrading a read lock");
|
|
hlock->read = 1;
|
|
hlock->acquire_ip = ip;
|
|
|
|
if (reacquire_held_locks(curr, depth, i))
|
|
return 0;
|
|
|
|
/*
|
|
* I took it apart and put it back together again, except now I have
|
|
* these 'spare' parts.. where shall I put them.
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth))
|
|
return 0;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Remove the lock to the list of currently held locks - this gets
|
|
* called on mutex_unlock()/spin_unlock*() (or on a failed
|
|
* mutex_lock_interruptible()).
|
|
*
|
|
* @nested is an hysterical artifact, needs a tree wide cleanup.
|
|
*/
|
|
static int
|
|
__lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
|
|
{
|
|
struct task_struct *curr = current;
|
|
struct held_lock *hlock;
|
|
unsigned int depth;
|
|
int ret, i;
|
|
|
|
if (unlikely(!debug_locks))
|
|
return 0;
|
|
|
|
ret = lock_release_crosslock(lock);
|
|
/*
|
|
* 2 means normal release operations are needed. Otherwise, it's
|
|
* ok just to return with '0:fail, 1:success'.
|
|
*/
|
|
if (ret != 2)
|
|
return ret;
|
|
|
|
depth = curr->lockdep_depth;
|
|
/*
|
|
* So we're all set to release this lock.. wait what lock? We don't
|
|
* own any locks, you've been drinking again?
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(depth <= 0))
|
|
return print_unlock_imbalance_bug(curr, lock, ip);
|
|
|
|
/*
|
|
* Check whether the lock exists in the current stack
|
|
* of held locks:
|
|
*/
|
|
hlock = find_held_lock(curr, lock, depth, &i);
|
|
if (!hlock)
|
|
return print_unlock_imbalance_bug(curr, lock, ip);
|
|
|
|
if (hlock->instance == lock)
|
|
lock_release_holdtime(hlock);
|
|
|
|
WARN(hlock->pin_count, "releasing a pinned lock\n");
|
|
|
|
if (hlock->references) {
|
|
hlock->references--;
|
|
if (hlock->references) {
|
|
/*
|
|
* We had, and after removing one, still have
|
|
* references, the current lock stack is still
|
|
* valid. We're done!
|
|
*/
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We have the right lock to unlock, 'hlock' points to it.
|
|
* Now we remove it from the stack, and add back the other
|
|
* entries (if any), recalculating the hash along the way:
|
|
*/
|
|
|
|
curr->lockdep_depth = i;
|
|
curr->curr_chain_key = hlock->prev_chain_key;
|
|
|
|
if (reacquire_held_locks(curr, depth, i + 1))
|
|
return 0;
|
|
|
|
/*
|
|
* We had N bottles of beer on the wall, we drank one, but now
|
|
* there's not N-1 bottles of beer left on the wall...
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(curr->lockdep_depth != depth - 1))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int __lock_is_held(struct lockdep_map *lock, int read)
|
|
{
|
|
struct task_struct *curr = current;
|
|
int i;
|
|
|
|
for (i = 0; i < curr->lockdep_depth; i++) {
|
|
struct held_lock *hlock = curr->held_locks + i;
|
|
|
|
if (match_held_lock(hlock, lock)) {
|
|
if (read == -1 || hlock->read == read)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct pin_cookie __lock_pin_lock(struct lockdep_map *lock)
|
|
{
|
|
struct pin_cookie cookie = NIL_COOKIE;
|
|
struct task_struct *curr = current;
|
|
int i;
|
|
|
|
if (unlikely(!debug_locks))
|
|
return cookie;
|
|
|
|
for (i = 0; i < curr->lockdep_depth; i++) {
|
|
struct held_lock *hlock = curr->held_locks + i;
|
|
|
|
if (match_held_lock(hlock, lock)) {
|
|
/*
|
|
* Grab 16bits of randomness; this is sufficient to not
|
|
* be guessable and still allows some pin nesting in
|
|
* our u32 pin_count.
|
|
*/
|
|
cookie.val = 1 + (prandom_u32() >> 16);
|
|
hlock->pin_count += cookie.val;
|
|
return cookie;
|
|
}
|
|
}
|
|
|
|
WARN(1, "pinning an unheld lock\n");
|
|
return cookie;
|
|
}
|
|
|
|
static void __lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
|
|
{
|
|
struct task_struct *curr = current;
|
|
int i;
|
|
|
|
if (unlikely(!debug_locks))
|
|
return;
|
|
|
|
for (i = 0; i < curr->lockdep_depth; i++) {
|
|
struct held_lock *hlock = curr->held_locks + i;
|
|
|
|
if (match_held_lock(hlock, lock)) {
|
|
hlock->pin_count += cookie.val;
|
|
return;
|
|
}
|
|
}
|
|
|
|
WARN(1, "pinning an unheld lock\n");
|
|
}
|
|
|
|
static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
|
|
{
|
|
struct task_struct *curr = current;
|
|
int i;
|
|
|
|
if (unlikely(!debug_locks))
|
|
return;
|
|
|
|
for (i = 0; i < curr->lockdep_depth; i++) {
|
|
struct held_lock *hlock = curr->held_locks + i;
|
|
|
|
if (match_held_lock(hlock, lock)) {
|
|
if (WARN(!hlock->pin_count, "unpinning an unpinned lock\n"))
|
|
return;
|
|
|
|
hlock->pin_count -= cookie.val;
|
|
|
|
if (WARN((int)hlock->pin_count < 0, "pin count corrupted\n"))
|
|
hlock->pin_count = 0;
|
|
|
|
return;
|
|
}
|
|
}
|
|
|
|
WARN(1, "unpinning an unheld lock\n");
|
|
}
|
|
|
|
/*
|
|
* Check whether we follow the irq-flags state precisely:
|
|
*/
|
|
static void check_flags(unsigned long flags)
|
|
{
|
|
#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
|
|
defined(CONFIG_TRACE_IRQFLAGS)
|
|
if (!debug_locks)
|
|
return;
|
|
|
|
if (irqs_disabled_flags(flags)) {
|
|
if (DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)) {
|
|
printk("possible reason: unannotated irqs-off.\n");
|
|
}
|
|
} else {
|
|
if (DEBUG_LOCKS_WARN_ON(!current->hardirqs_enabled)) {
|
|
printk("possible reason: unannotated irqs-on.\n");
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We dont accurately track softirq state in e.g.
|
|
* hardirq contexts (such as on 4KSTACKS), so only
|
|
* check if not in hardirq contexts:
|
|
*/
|
|
if (!hardirq_count()) {
|
|
if (softirq_count()) {
|
|
/* like the above, but with softirqs */
|
|
DEBUG_LOCKS_WARN_ON(current->softirqs_enabled);
|
|
} else {
|
|
/* lick the above, does it taste good? */
|
|
DEBUG_LOCKS_WARN_ON(!current->softirqs_enabled);
|
|
}
|
|
}
|
|
|
|
if (!debug_locks)
|
|
print_irqtrace_events(current);
|
|
#endif
|
|
}
|
|
|
|
void lock_set_class(struct lockdep_map *lock, const char *name,
|
|
struct lock_class_key *key, unsigned int subclass,
|
|
unsigned long ip)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (unlikely(current->lockdep_recursion))
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
current->lockdep_recursion = 1;
|
|
check_flags(flags);
|
|
if (__lock_set_class(lock, name, key, subclass, ip))
|
|
check_chain_key(current);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lock_set_class);
|
|
|
|
void lock_downgrade(struct lockdep_map *lock, unsigned long ip)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (unlikely(current->lockdep_recursion))
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
current->lockdep_recursion = 1;
|
|
check_flags(flags);
|
|
if (__lock_downgrade(lock, ip))
|
|
check_chain_key(current);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lock_downgrade);
|
|
|
|
/*
|
|
* We are not always called with irqs disabled - do that here,
|
|
* and also avoid lockdep recursion:
|
|
*/
|
|
void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
|
|
int trylock, int read, int check,
|
|
struct lockdep_map *nest_lock, unsigned long ip)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (unlikely(current->lockdep_recursion))
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
check_flags(flags);
|
|
|
|
current->lockdep_recursion = 1;
|
|
trace_lock_acquire(lock, subclass, trylock, read, check, nest_lock, ip);
|
|
__lock_acquire(lock, subclass, trylock, read, check,
|
|
irqs_disabled_flags(flags), nest_lock, ip, 0, 0);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lock_acquire);
|
|
|
|
void lock_release(struct lockdep_map *lock, int nested,
|
|
unsigned long ip)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (unlikely(current->lockdep_recursion))
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
check_flags(flags);
|
|
current->lockdep_recursion = 1;
|
|
trace_lock_release(lock, ip);
|
|
if (__lock_release(lock, nested, ip))
|
|
check_chain_key(current);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lock_release);
|
|
|
|
int lock_is_held_type(struct lockdep_map *lock, int read)
|
|
{
|
|
unsigned long flags;
|
|
int ret = 0;
|
|
|
|
if (unlikely(current->lockdep_recursion))
|
|
return 1; /* avoid false negative lockdep_assert_held() */
|
|
|
|
raw_local_irq_save(flags);
|
|
check_flags(flags);
|
|
|
|
current->lockdep_recursion = 1;
|
|
ret = __lock_is_held(lock, read);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(lock_is_held_type);
|
|
|
|
struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
|
|
{
|
|
struct pin_cookie cookie = NIL_COOKIE;
|
|
unsigned long flags;
|
|
|
|
if (unlikely(current->lockdep_recursion))
|
|
return cookie;
|
|
|
|
raw_local_irq_save(flags);
|
|
check_flags(flags);
|
|
|
|
current->lockdep_recursion = 1;
|
|
cookie = __lock_pin_lock(lock);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
|
|
return cookie;
|
|
}
|
|
EXPORT_SYMBOL_GPL(lock_pin_lock);
|
|
|
|
void lock_repin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (unlikely(current->lockdep_recursion))
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
check_flags(flags);
|
|
|
|
current->lockdep_recursion = 1;
|
|
__lock_repin_lock(lock, cookie);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lock_repin_lock);
|
|
|
|
void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (unlikely(current->lockdep_recursion))
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
check_flags(flags);
|
|
|
|
current->lockdep_recursion = 1;
|
|
__lock_unpin_lock(lock, cookie);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lock_unpin_lock);
|
|
|
|
#ifdef CONFIG_LOCK_STAT
|
|
static int
|
|
print_lock_contention_bug(struct task_struct *curr, struct lockdep_map *lock,
|
|
unsigned long ip)
|
|
{
|
|
if (!debug_locks_off())
|
|
return 0;
|
|
if (debug_locks_silent)
|
|
return 0;
|
|
|
|
pr_warn("\n");
|
|
pr_warn("=================================\n");
|
|
pr_warn("WARNING: bad contention detected!\n");
|
|
print_kernel_ident();
|
|
pr_warn("---------------------------------\n");
|
|
pr_warn("%s/%d is trying to contend lock (",
|
|
curr->comm, task_pid_nr(curr));
|
|
print_lockdep_cache(lock);
|
|
pr_cont(") at:\n");
|
|
print_ip_sym(ip);
|
|
pr_warn("but there are no locks held!\n");
|
|
pr_warn("\nother info that might help us debug this:\n");
|
|
lockdep_print_held_locks(curr);
|
|
|
|
pr_warn("\nstack backtrace:\n");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void
|
|
__lock_contended(struct lockdep_map *lock, unsigned long ip)
|
|
{
|
|
struct task_struct *curr = current;
|
|
struct held_lock *hlock;
|
|
struct lock_class_stats *stats;
|
|
unsigned int depth;
|
|
int i, contention_point, contending_point;
|
|
|
|
depth = curr->lockdep_depth;
|
|
/*
|
|
* Whee, we contended on this lock, except it seems we're not
|
|
* actually trying to acquire anything much at all..
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!depth))
|
|
return;
|
|
|
|
hlock = find_held_lock(curr, lock, depth, &i);
|
|
if (!hlock) {
|
|
print_lock_contention_bug(curr, lock, ip);
|
|
return;
|
|
}
|
|
|
|
if (hlock->instance != lock)
|
|
return;
|
|
|
|
hlock->waittime_stamp = lockstat_clock();
|
|
|
|
contention_point = lock_point(hlock_class(hlock)->contention_point, ip);
|
|
contending_point = lock_point(hlock_class(hlock)->contending_point,
|
|
lock->ip);
|
|
|
|
stats = get_lock_stats(hlock_class(hlock));
|
|
if (contention_point < LOCKSTAT_POINTS)
|
|
stats->contention_point[contention_point]++;
|
|
if (contending_point < LOCKSTAT_POINTS)
|
|
stats->contending_point[contending_point]++;
|
|
if (lock->cpu != smp_processor_id())
|
|
stats->bounces[bounce_contended + !!hlock->read]++;
|
|
put_lock_stats(stats);
|
|
}
|
|
|
|
static void
|
|
__lock_acquired(struct lockdep_map *lock, unsigned long ip)
|
|
{
|
|
struct task_struct *curr = current;
|
|
struct held_lock *hlock;
|
|
struct lock_class_stats *stats;
|
|
unsigned int depth;
|
|
u64 now, waittime = 0;
|
|
int i, cpu;
|
|
|
|
depth = curr->lockdep_depth;
|
|
/*
|
|
* Yay, we acquired ownership of this lock we didn't try to
|
|
* acquire, how the heck did that happen?
|
|
*/
|
|
if (DEBUG_LOCKS_WARN_ON(!depth))
|
|
return;
|
|
|
|
hlock = find_held_lock(curr, lock, depth, &i);
|
|
if (!hlock) {
|
|
print_lock_contention_bug(curr, lock, _RET_IP_);
|
|
return;
|
|
}
|
|
|
|
if (hlock->instance != lock)
|
|
return;
|
|
|
|
cpu = smp_processor_id();
|
|
if (hlock->waittime_stamp) {
|
|
now = lockstat_clock();
|
|
waittime = now - hlock->waittime_stamp;
|
|
hlock->holdtime_stamp = now;
|
|
}
|
|
|
|
trace_lock_acquired(lock, ip);
|
|
|
|
stats = get_lock_stats(hlock_class(hlock));
|
|
if (waittime) {
|
|
if (hlock->read)
|
|
lock_time_inc(&stats->read_waittime, waittime);
|
|
else
|
|
lock_time_inc(&stats->write_waittime, waittime);
|
|
}
|
|
if (lock->cpu != cpu)
|
|
stats->bounces[bounce_acquired + !!hlock->read]++;
|
|
put_lock_stats(stats);
|
|
|
|
lock->cpu = cpu;
|
|
lock->ip = ip;
|
|
}
|
|
|
|
void lock_contended(struct lockdep_map *lock, unsigned long ip)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (unlikely(!lock_stat))
|
|
return;
|
|
|
|
if (unlikely(current->lockdep_recursion))
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
check_flags(flags);
|
|
current->lockdep_recursion = 1;
|
|
trace_lock_contended(lock, ip);
|
|
__lock_contended(lock, ip);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lock_contended);
|
|
|
|
void lock_acquired(struct lockdep_map *lock, unsigned long ip)
|
|
{
|
|
unsigned long flags;
|
|
|
|
if (unlikely(!lock_stat))
|
|
return;
|
|
|
|
if (unlikely(current->lockdep_recursion))
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
check_flags(flags);
|
|
current->lockdep_recursion = 1;
|
|
__lock_acquired(lock, ip);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lock_acquired);
|
|
#endif
|
|
|
|
/*
|
|
* Used by the testsuite, sanitize the validator state
|
|
* after a simulated failure:
|
|
*/
|
|
|
|
void lockdep_reset(void)
|
|
{
|
|
unsigned long flags;
|
|
int i;
|
|
|
|
raw_local_irq_save(flags);
|
|
current->curr_chain_key = 0;
|
|
current->lockdep_depth = 0;
|
|
current->lockdep_recursion = 0;
|
|
memset(current->held_locks, 0, MAX_LOCK_DEPTH*sizeof(struct held_lock));
|
|
nr_hardirq_chains = 0;
|
|
nr_softirq_chains = 0;
|
|
nr_process_chains = 0;
|
|
debug_locks = 1;
|
|
for (i = 0; i < CHAINHASH_SIZE; i++)
|
|
INIT_HLIST_HEAD(chainhash_table + i);
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
|
|
static void zap_class(struct lock_class *class)
|
|
{
|
|
int i;
|
|
|
|
/*
|
|
* Remove all dependencies this lock is
|
|
* involved in:
|
|
*/
|
|
for (i = 0; i < nr_list_entries; i++) {
|
|
if (list_entries[i].class == class)
|
|
list_del_rcu(&list_entries[i].entry);
|
|
}
|
|
/*
|
|
* Unhash the class and remove it from the all_lock_classes list:
|
|
*/
|
|
hlist_del_rcu(&class->hash_entry);
|
|
list_del_rcu(&class->lock_entry);
|
|
|
|
RCU_INIT_POINTER(class->key, NULL);
|
|
RCU_INIT_POINTER(class->name, NULL);
|
|
}
|
|
|
|
static inline int within(const void *addr, void *start, unsigned long size)
|
|
{
|
|
return addr >= start && addr < start + size;
|
|
}
|
|
|
|
/*
|
|
* Used in module.c to remove lock classes from memory that is going to be
|
|
* freed; and possibly re-used by other modules.
|
|
*
|
|
* We will have had one sync_sched() before getting here, so we're guaranteed
|
|
* nobody will look up these exact classes -- they're properly dead but still
|
|
* allocated.
|
|
*/
|
|
void lockdep_free_key_range(void *start, unsigned long size)
|
|
{
|
|
struct lock_class *class;
|
|
struct hlist_head *head;
|
|
unsigned long flags;
|
|
int i;
|
|
int locked;
|
|
|
|
raw_local_irq_save(flags);
|
|
locked = graph_lock();
|
|
|
|
/*
|
|
* Unhash all classes that were created by this module:
|
|
*/
|
|
for (i = 0; i < CLASSHASH_SIZE; i++) {
|
|
head = classhash_table + i;
|
|
hlist_for_each_entry_rcu(class, head, hash_entry) {
|
|
if (within(class->key, start, size))
|
|
zap_class(class);
|
|
else if (within(class->name, start, size))
|
|
zap_class(class);
|
|
}
|
|
}
|
|
|
|
if (locked)
|
|
graph_unlock();
|
|
raw_local_irq_restore(flags);
|
|
|
|
/*
|
|
* Wait for any possible iterators from look_up_lock_class() to pass
|
|
* before continuing to free the memory they refer to.
|
|
*
|
|
* sync_sched() is sufficient because the read-side is IRQ disable.
|
|
*/
|
|
synchronize_sched();
|
|
|
|
/*
|
|
* XXX at this point we could return the resources to the pool;
|
|
* instead we leak them. We would need to change to bitmap allocators
|
|
* instead of the linear allocators we have now.
|
|
*/
|
|
}
|
|
|
|
void lockdep_reset_lock(struct lockdep_map *lock)
|
|
{
|
|
struct lock_class *class;
|
|
struct hlist_head *head;
|
|
unsigned long flags;
|
|
int i, j;
|
|
int locked;
|
|
|
|
raw_local_irq_save(flags);
|
|
|
|
/*
|
|
* Remove all classes this lock might have:
|
|
*/
|
|
for (j = 0; j < MAX_LOCKDEP_SUBCLASSES; j++) {
|
|
/*
|
|
* If the class exists we look it up and zap it:
|
|
*/
|
|
class = look_up_lock_class(lock, j);
|
|
if (!IS_ERR_OR_NULL(class))
|
|
zap_class(class);
|
|
}
|
|
/*
|
|
* Debug check: in the end all mapped classes should
|
|
* be gone.
|
|
*/
|
|
locked = graph_lock();
|
|
for (i = 0; i < CLASSHASH_SIZE; i++) {
|
|
head = classhash_table + i;
|
|
hlist_for_each_entry_rcu(class, head, hash_entry) {
|
|
int match = 0;
|
|
|
|
for (j = 0; j < NR_LOCKDEP_CACHING_CLASSES; j++)
|
|
match |= class == lock->class_cache[j];
|
|
|
|
if (unlikely(match)) {
|
|
if (debug_locks_off_graph_unlock()) {
|
|
/*
|
|
* We all just reset everything, how did it match?
|
|
*/
|
|
WARN_ON(1);
|
|
}
|
|
goto out_restore;
|
|
}
|
|
}
|
|
}
|
|
if (locked)
|
|
graph_unlock();
|
|
|
|
out_restore:
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
|
|
void __init lockdep_info(void)
|
|
{
|
|
printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
|
|
|
|
printk("... MAX_LOCKDEP_SUBCLASSES: %lu\n", MAX_LOCKDEP_SUBCLASSES);
|
|
printk("... MAX_LOCK_DEPTH: %lu\n", MAX_LOCK_DEPTH);
|
|
printk("... MAX_LOCKDEP_KEYS: %lu\n", MAX_LOCKDEP_KEYS);
|
|
printk("... CLASSHASH_SIZE: %lu\n", CLASSHASH_SIZE);
|
|
printk("... MAX_LOCKDEP_ENTRIES: %lu\n", MAX_LOCKDEP_ENTRIES);
|
|
printk("... MAX_LOCKDEP_CHAINS: %lu\n", MAX_LOCKDEP_CHAINS);
|
|
printk("... CHAINHASH_SIZE: %lu\n", CHAINHASH_SIZE);
|
|
|
|
printk(" memory used by lock dependency info: %lu kB\n",
|
|
(sizeof(struct lock_class) * MAX_LOCKDEP_KEYS +
|
|
sizeof(struct list_head) * CLASSHASH_SIZE +
|
|
sizeof(struct lock_list) * MAX_LOCKDEP_ENTRIES +
|
|
sizeof(struct lock_chain) * MAX_LOCKDEP_CHAINS +
|
|
sizeof(struct list_head) * CHAINHASH_SIZE
|
|
#ifdef CONFIG_PROVE_LOCKING
|
|
+ sizeof(struct circular_queue)
|
|
#endif
|
|
) / 1024
|
|
);
|
|
|
|
printk(" per task-struct memory footprint: %lu bytes\n",
|
|
sizeof(struct held_lock) * MAX_LOCK_DEPTH);
|
|
}
|
|
|
|
static void
|
|
print_freed_lock_bug(struct task_struct *curr, const void *mem_from,
|
|
const void *mem_to, struct held_lock *hlock)
|
|
{
|
|
if (!debug_locks_off())
|
|
return;
|
|
if (debug_locks_silent)
|
|
return;
|
|
|
|
pr_warn("\n");
|
|
pr_warn("=========================\n");
|
|
pr_warn("WARNING: held lock freed!\n");
|
|
print_kernel_ident();
|
|
pr_warn("-------------------------\n");
|
|
pr_warn("%s/%d is freeing memory %p-%p, with a lock still held there!\n",
|
|
curr->comm, task_pid_nr(curr), mem_from, mem_to-1);
|
|
print_lock(hlock);
|
|
lockdep_print_held_locks(curr);
|
|
|
|
pr_warn("\nstack backtrace:\n");
|
|
dump_stack();
|
|
}
|
|
|
|
static inline int not_in_range(const void* mem_from, unsigned long mem_len,
|
|
const void* lock_from, unsigned long lock_len)
|
|
{
|
|
return lock_from + lock_len <= mem_from ||
|
|
mem_from + mem_len <= lock_from;
|
|
}
|
|
|
|
/*
|
|
* Called when kernel memory is freed (or unmapped), or if a lock
|
|
* is destroyed or reinitialized - this code checks whether there is
|
|
* any held lock in the memory range of <from> to <to>:
|
|
*/
|
|
void debug_check_no_locks_freed(const void *mem_from, unsigned long mem_len)
|
|
{
|
|
struct task_struct *curr = current;
|
|
struct held_lock *hlock;
|
|
unsigned long flags;
|
|
int i;
|
|
|
|
if (unlikely(!debug_locks))
|
|
return;
|
|
|
|
local_irq_save(flags);
|
|
for (i = 0; i < curr->lockdep_depth; i++) {
|
|
hlock = curr->held_locks + i;
|
|
|
|
if (not_in_range(mem_from, mem_len, hlock->instance,
|
|
sizeof(*hlock->instance)))
|
|
continue;
|
|
|
|
print_freed_lock_bug(curr, mem_from, mem_from + mem_len, hlock);
|
|
break;
|
|
}
|
|
local_irq_restore(flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(debug_check_no_locks_freed);
|
|
|
|
static void print_held_locks_bug(void)
|
|
{
|
|
if (!debug_locks_off())
|
|
return;
|
|
if (debug_locks_silent)
|
|
return;
|
|
|
|
pr_warn("\n");
|
|
pr_warn("====================================\n");
|
|
pr_warn("WARNING: %s/%d still has locks held!\n",
|
|
current->comm, task_pid_nr(current));
|
|
print_kernel_ident();
|
|
pr_warn("------------------------------------\n");
|
|
lockdep_print_held_locks(current);
|
|
pr_warn("\nstack backtrace:\n");
|
|
dump_stack();
|
|
}
|
|
|
|
void debug_check_no_locks_held(void)
|
|
{
|
|
if (unlikely(current->lockdep_depth > 0))
|
|
print_held_locks_bug();
|
|
}
|
|
EXPORT_SYMBOL_GPL(debug_check_no_locks_held);
|
|
|
|
#ifdef __KERNEL__
|
|
void debug_show_all_locks(void)
|
|
{
|
|
struct task_struct *g, *p;
|
|
int count = 10;
|
|
int unlock = 1;
|
|
|
|
if (unlikely(!debug_locks)) {
|
|
pr_warn("INFO: lockdep is turned off.\n");
|
|
return;
|
|
}
|
|
pr_warn("\nShowing all locks held in the system:\n");
|
|
|
|
/*
|
|
* Here we try to get the tasklist_lock as hard as possible,
|
|
* if not successful after 2 seconds we ignore it (but keep
|
|
* trying). This is to enable a debug printout even if a
|
|
* tasklist_lock-holding task deadlocks or crashes.
|
|
*/
|
|
retry:
|
|
if (!read_trylock(&tasklist_lock)) {
|
|
if (count == 10)
|
|
pr_warn("hm, tasklist_lock locked, retrying... ");
|
|
if (count) {
|
|
count--;
|
|
pr_cont(" #%d", 10-count);
|
|
mdelay(200);
|
|
goto retry;
|
|
}
|
|
pr_cont(" ignoring it.\n");
|
|
unlock = 0;
|
|
} else {
|
|
if (count != 10)
|
|
pr_cont(" locked it.\n");
|
|
}
|
|
|
|
do_each_thread(g, p) {
|
|
/*
|
|
* It's not reliable to print a task's held locks
|
|
* if it's not sleeping (or if it's not the current
|
|
* task):
|
|
*/
|
|
if (p->state == TASK_RUNNING && p != current)
|
|
continue;
|
|
if (p->lockdep_depth)
|
|
lockdep_print_held_locks(p);
|
|
if (!unlock)
|
|
if (read_trylock(&tasklist_lock))
|
|
unlock = 1;
|
|
} while_each_thread(g, p);
|
|
|
|
pr_warn("\n");
|
|
pr_warn("=============================================\n\n");
|
|
|
|
if (unlock)
|
|
read_unlock(&tasklist_lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(debug_show_all_locks);
|
|
#endif
|
|
|
|
/*
|
|
* Careful: only use this function if you are sure that
|
|
* the task cannot run in parallel!
|
|
*/
|
|
void debug_show_held_locks(struct task_struct *task)
|
|
{
|
|
if (unlikely(!debug_locks)) {
|
|
printk("INFO: lockdep is turned off.\n");
|
|
return;
|
|
}
|
|
lockdep_print_held_locks(task);
|
|
}
|
|
EXPORT_SYMBOL_GPL(debug_show_held_locks);
|
|
|
|
asmlinkage __visible void lockdep_sys_exit(void)
|
|
{
|
|
struct task_struct *curr = current;
|
|
|
|
if (unlikely(curr->lockdep_depth)) {
|
|
if (!debug_locks_off())
|
|
return;
|
|
pr_warn("\n");
|
|
pr_warn("================================================\n");
|
|
pr_warn("WARNING: lock held when returning to user space!\n");
|
|
print_kernel_ident();
|
|
pr_warn("------------------------------------------------\n");
|
|
pr_warn("%s/%d is leaving the kernel with locks still held!\n",
|
|
curr->comm, curr->pid);
|
|
lockdep_print_held_locks(curr);
|
|
}
|
|
|
|
/*
|
|
* The lock history for each syscall should be independent. So wipe the
|
|
* slate clean on return to userspace.
|
|
*/
|
|
lockdep_invariant_state(false);
|
|
}
|
|
|
|
void lockdep_rcu_suspicious(const char *file, const int line, const char *s)
|
|
{
|
|
struct task_struct *curr = current;
|
|
|
|
/* Note: the following can be executed concurrently, so be careful. */
|
|
pr_warn("\n");
|
|
pr_warn("=============================\n");
|
|
pr_warn("WARNING: suspicious RCU usage\n");
|
|
print_kernel_ident();
|
|
pr_warn("-----------------------------\n");
|
|
pr_warn("%s:%d %s!\n", file, line, s);
|
|
pr_warn("\nother info that might help us debug this:\n\n");
|
|
pr_warn("\n%srcu_scheduler_active = %d, debug_locks = %d\n",
|
|
!rcu_lockdep_current_cpu_online()
|
|
? "RCU used illegally from offline CPU!\n"
|
|
: !rcu_is_watching()
|
|
? "RCU used illegally from idle CPU!\n"
|
|
: "",
|
|
rcu_scheduler_active, debug_locks);
|
|
|
|
/*
|
|
* If a CPU is in the RCU-free window in idle (ie: in the section
|
|
* between rcu_idle_enter() and rcu_idle_exit(), then RCU
|
|
* considers that CPU to be in an "extended quiescent state",
|
|
* which means that RCU will be completely ignoring that CPU.
|
|
* Therefore, rcu_read_lock() and friends have absolutely no
|
|
* effect on a CPU running in that state. In other words, even if
|
|
* such an RCU-idle CPU has called rcu_read_lock(), RCU might well
|
|
* delete data structures out from under it. RCU really has no
|
|
* choice here: we need to keep an RCU-free window in idle where
|
|
* the CPU may possibly enter into low power mode. This way we can
|
|
* notice an extended quiescent state to other CPUs that started a grace
|
|
* period. Otherwise we would delay any grace period as long as we run
|
|
* in the idle task.
|
|
*
|
|
* So complain bitterly if someone does call rcu_read_lock(),
|
|
* rcu_read_lock_bh() and so on from extended quiescent states.
|
|
*/
|
|
if (!rcu_is_watching())
|
|
pr_warn("RCU used illegally from extended quiescent state!\n");
|
|
|
|
lockdep_print_held_locks(curr);
|
|
pr_warn("\nstack backtrace:\n");
|
|
dump_stack();
|
|
}
|
|
EXPORT_SYMBOL_GPL(lockdep_rcu_suspicious);
|
|
|
|
#ifdef CONFIG_LOCKDEP_CROSSRELEASE
|
|
|
|
/*
|
|
* Crossrelease works by recording a lock history for each thread and
|
|
* connecting those historic locks that were taken after the
|
|
* wait_for_completion() in the complete() context.
|
|
*
|
|
* Task-A Task-B
|
|
*
|
|
* mutex_lock(&A);
|
|
* mutex_unlock(&A);
|
|
*
|
|
* wait_for_completion(&C);
|
|
* lock_acquire_crosslock();
|
|
* atomic_inc_return(&cross_gen_id);
|
|
* |
|
|
* | mutex_lock(&B);
|
|
* | mutex_unlock(&B);
|
|
* |
|
|
* | complete(&C);
|
|
* `-- lock_commit_crosslock();
|
|
*
|
|
* Which will then add a dependency between B and C.
|
|
*/
|
|
|
|
#define xhlock(i) (current->xhlocks[(i) % MAX_XHLOCKS_NR])
|
|
|
|
/*
|
|
* Whenever a crosslock is held, cross_gen_id will be increased.
|
|
*/
|
|
static atomic_t cross_gen_id; /* Can be wrapped */
|
|
|
|
/*
|
|
* Make an entry of the ring buffer invalid.
|
|
*/
|
|
static inline void invalidate_xhlock(struct hist_lock *xhlock)
|
|
{
|
|
/*
|
|
* Normally, xhlock->hlock.instance must be !NULL.
|
|
*/
|
|
xhlock->hlock.instance = NULL;
|
|
}
|
|
|
|
/*
|
|
* Lock history stacks; we have 2 nested lock history stacks:
|
|
*
|
|
* HARD(IRQ)
|
|
* SOFT(IRQ)
|
|
*
|
|
* The thing is that once we complete a HARD/SOFT IRQ the future task locks
|
|
* should not depend on any of the locks observed while running the IRQ. So
|
|
* what we do is rewind the history buffer and erase all our knowledge of that
|
|
* temporal event.
|
|
*/
|
|
|
|
void crossrelease_hist_start(enum xhlock_context_t c)
|
|
{
|
|
struct task_struct *cur = current;
|
|
|
|
if (!cur->xhlocks)
|
|
return;
|
|
|
|
cur->xhlock_idx_hist[c] = cur->xhlock_idx;
|
|
cur->hist_id_save[c] = cur->hist_id;
|
|
}
|
|
|
|
void crossrelease_hist_end(enum xhlock_context_t c)
|
|
{
|
|
struct task_struct *cur = current;
|
|
|
|
if (cur->xhlocks) {
|
|
unsigned int idx = cur->xhlock_idx_hist[c];
|
|
struct hist_lock *h = &xhlock(idx);
|
|
|
|
cur->xhlock_idx = idx;
|
|
|
|
/* Check if the ring was overwritten. */
|
|
if (h->hist_id != cur->hist_id_save[c])
|
|
invalidate_xhlock(h);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* lockdep_invariant_state() is used to annotate independence inside a task, to
|
|
* make one task look like multiple independent 'tasks'.
|
|
*
|
|
* Take for instance workqueues; each work is independent of the last. The
|
|
* completion of a future work does not depend on the completion of a past work
|
|
* (in general). Therefore we must not carry that (lock) dependency across
|
|
* works.
|
|
*
|
|
* This is true for many things; pretty much all kthreads fall into this
|
|
* pattern, where they have an invariant state and future completions do not
|
|
* depend on past completions. Its just that since they all have the 'same'
|
|
* form -- the kthread does the same over and over -- it doesn't typically
|
|
* matter.
|
|
*
|
|
* The same is true for system-calls, once a system call is completed (we've
|
|
* returned to userspace) the next system call does not depend on the lock
|
|
* history of the previous system call.
|
|
*
|
|
* They key property for independence, this invariant state, is that it must be
|
|
* a point where we hold no locks and have no history. Because if we were to
|
|
* hold locks, the restore at _end() would not necessarily recover it's history
|
|
* entry. Similarly, independence per-definition means it does not depend on
|
|
* prior state.
|
|
*/
|
|
void lockdep_invariant_state(bool force)
|
|
{
|
|
/*
|
|
* We call this at an invariant point, no current state, no history.
|
|
* Verify the former, enforce the latter.
|
|
*/
|
|
WARN_ON_ONCE(!force && current->lockdep_depth);
|
|
if (current->xhlocks)
|
|
invalidate_xhlock(&xhlock(current->xhlock_idx));
|
|
}
|
|
|
|
static int cross_lock(struct lockdep_map *lock)
|
|
{
|
|
return lock ? lock->cross : 0;
|
|
}
|
|
|
|
/*
|
|
* This is needed to decide the relationship between wrapable variables.
|
|
*/
|
|
static inline int before(unsigned int a, unsigned int b)
|
|
{
|
|
return (int)(a - b) < 0;
|
|
}
|
|
|
|
static inline struct lock_class *xhlock_class(struct hist_lock *xhlock)
|
|
{
|
|
return hlock_class(&xhlock->hlock);
|
|
}
|
|
|
|
static inline struct lock_class *xlock_class(struct cross_lock *xlock)
|
|
{
|
|
return hlock_class(&xlock->hlock);
|
|
}
|
|
|
|
/*
|
|
* Should we check a dependency with previous one?
|
|
*/
|
|
static inline int depend_before(struct held_lock *hlock)
|
|
{
|
|
return hlock->read != 2 && hlock->check && !hlock->trylock;
|
|
}
|
|
|
|
/*
|
|
* Should we check a dependency with next one?
|
|
*/
|
|
static inline int depend_after(struct held_lock *hlock)
|
|
{
|
|
return hlock->read != 2 && hlock->check;
|
|
}
|
|
|
|
/*
|
|
* Check if the xhlock is valid, which would be false if,
|
|
*
|
|
* 1. Has not used after initializaion yet.
|
|
* 2. Got invalidated.
|
|
*
|
|
* Remind hist_lock is implemented as a ring buffer.
|
|
*/
|
|
static inline int xhlock_valid(struct hist_lock *xhlock)
|
|
{
|
|
/*
|
|
* xhlock->hlock.instance must be !NULL.
|
|
*/
|
|
return !!xhlock->hlock.instance;
|
|
}
|
|
|
|
/*
|
|
* Record a hist_lock entry.
|
|
*
|
|
* Irq disable is only required.
|
|
*/
|
|
static void add_xhlock(struct held_lock *hlock)
|
|
{
|
|
unsigned int idx = ++current->xhlock_idx;
|
|
struct hist_lock *xhlock = &xhlock(idx);
|
|
|
|
#ifdef CONFIG_DEBUG_LOCKDEP
|
|
/*
|
|
* This can be done locklessly because they are all task-local
|
|
* state, we must however ensure IRQs are disabled.
|
|
*/
|
|
WARN_ON_ONCE(!irqs_disabled());
|
|
#endif
|
|
|
|
/* Initialize hist_lock's members */
|
|
xhlock->hlock = *hlock;
|
|
xhlock->hist_id = ++current->hist_id;
|
|
|
|
xhlock->trace.nr_entries = 0;
|
|
xhlock->trace.max_entries = MAX_XHLOCK_TRACE_ENTRIES;
|
|
xhlock->trace.entries = xhlock->trace_entries;
|
|
xhlock->trace.skip = 3;
|
|
save_stack_trace(&xhlock->trace);
|
|
}
|
|
|
|
static inline int same_context_xhlock(struct hist_lock *xhlock)
|
|
{
|
|
return xhlock->hlock.irq_context == task_irq_context(current);
|
|
}
|
|
|
|
/*
|
|
* This should be lockless as far as possible because this would be
|
|
* called very frequently.
|
|
*/
|
|
static void check_add_xhlock(struct held_lock *hlock)
|
|
{
|
|
/*
|
|
* Record a hist_lock, only in case that acquisitions ahead
|
|
* could depend on the held_lock. For example, if the held_lock
|
|
* is trylock then acquisitions ahead never depends on that.
|
|
* In that case, we don't need to record it. Just return.
|
|
*/
|
|
if (!current->xhlocks || !depend_before(hlock))
|
|
return;
|
|
|
|
add_xhlock(hlock);
|
|
}
|
|
|
|
/*
|
|
* For crosslock.
|
|
*/
|
|
static int add_xlock(struct held_lock *hlock)
|
|
{
|
|
struct cross_lock *xlock;
|
|
unsigned int gen_id;
|
|
|
|
if (!graph_lock())
|
|
return 0;
|
|
|
|
xlock = &((struct lockdep_map_cross *)hlock->instance)->xlock;
|
|
|
|
/*
|
|
* When acquisitions for a crosslock are overlapped, we use
|
|
* nr_acquire to perform commit for them, based on cross_gen_id
|
|
* of the first acquisition, which allows to add additional
|
|
* dependencies.
|
|
*
|
|
* Moreover, when no acquisition of a crosslock is in progress,
|
|
* we should not perform commit because the lock might not exist
|
|
* any more, which might cause incorrect memory access. So we
|
|
* have to track the number of acquisitions of a crosslock.
|
|
*
|
|
* depend_after() is necessary to initialize only the first
|
|
* valid xlock so that the xlock can be used on its commit.
|
|
*/
|
|
if (xlock->nr_acquire++ && depend_after(&xlock->hlock))
|
|
goto unlock;
|
|
|
|
gen_id = (unsigned int)atomic_inc_return(&cross_gen_id);
|
|
xlock->hlock = *hlock;
|
|
xlock->hlock.gen_id = gen_id;
|
|
unlock:
|
|
graph_unlock();
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Called for both normal and crosslock acquires. Normal locks will be
|
|
* pushed on the hist_lock queue. Cross locks will record state and
|
|
* stop regular lock_acquire() to avoid being placed on the held_lock
|
|
* stack.
|
|
*
|
|
* Return: 0 - failure;
|
|
* 1 - crosslock, done;
|
|
* 2 - normal lock, continue to held_lock[] ops.
|
|
*/
|
|
static int lock_acquire_crosslock(struct held_lock *hlock)
|
|
{
|
|
/*
|
|
* CONTEXT 1 CONTEXT 2
|
|
* --------- ---------
|
|
* lock A (cross)
|
|
* X = atomic_inc_return(&cross_gen_id)
|
|
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
* Y = atomic_read_acquire(&cross_gen_id)
|
|
* lock B
|
|
*
|
|
* atomic_read_acquire() is for ordering between A and B,
|
|
* IOW, A happens before B, when CONTEXT 2 see Y >= X.
|
|
*
|
|
* Pairs with atomic_inc_return() in add_xlock().
|
|
*/
|
|
hlock->gen_id = (unsigned int)atomic_read_acquire(&cross_gen_id);
|
|
|
|
if (cross_lock(hlock->instance))
|
|
return add_xlock(hlock);
|
|
|
|
check_add_xhlock(hlock);
|
|
return 2;
|
|
}
|
|
|
|
static int copy_trace(struct stack_trace *trace)
|
|
{
|
|
unsigned long *buf = stack_trace + nr_stack_trace_entries;
|
|
unsigned int max_nr = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries;
|
|
unsigned int nr = min(max_nr, trace->nr_entries);
|
|
|
|
trace->nr_entries = nr;
|
|
memcpy(buf, trace->entries, nr * sizeof(trace->entries[0]));
|
|
trace->entries = buf;
|
|
nr_stack_trace_entries += nr;
|
|
|
|
if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES-1) {
|
|
if (!debug_locks_off_graph_unlock())
|
|
return 0;
|
|
|
|
print_lockdep_off("BUG: MAX_STACK_TRACE_ENTRIES too low!");
|
|
dump_stack();
|
|
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int commit_xhlock(struct cross_lock *xlock, struct hist_lock *xhlock)
|
|
{
|
|
unsigned int xid, pid;
|
|
u64 chain_key;
|
|
|
|
xid = xlock_class(xlock) - lock_classes;
|
|
chain_key = iterate_chain_key((u64)0, xid);
|
|
pid = xhlock_class(xhlock) - lock_classes;
|
|
chain_key = iterate_chain_key(chain_key, pid);
|
|
|
|
if (lookup_chain_cache(chain_key))
|
|
return 1;
|
|
|
|
if (!add_chain_cache_classes(xid, pid, xhlock->hlock.irq_context,
|
|
chain_key))
|
|
return 0;
|
|
|
|
if (!check_prev_add(current, &xlock->hlock, &xhlock->hlock, 1,
|
|
&xhlock->trace, copy_trace))
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static void commit_xhlocks(struct cross_lock *xlock)
|
|
{
|
|
unsigned int cur = current->xhlock_idx;
|
|
unsigned int prev_hist_id = xhlock(cur).hist_id;
|
|
unsigned int i;
|
|
|
|
if (!graph_lock())
|
|
return;
|
|
|
|
if (xlock->nr_acquire) {
|
|
for (i = 0; i < MAX_XHLOCKS_NR; i++) {
|
|
struct hist_lock *xhlock = &xhlock(cur - i);
|
|
|
|
if (!xhlock_valid(xhlock))
|
|
break;
|
|
|
|
if (before(xhlock->hlock.gen_id, xlock->hlock.gen_id))
|
|
break;
|
|
|
|
if (!same_context_xhlock(xhlock))
|
|
break;
|
|
|
|
/*
|
|
* Filter out the cases where the ring buffer was
|
|
* overwritten and the current entry has a bigger
|
|
* hist_id than the previous one, which is impossible
|
|
* otherwise:
|
|
*/
|
|
if (unlikely(before(prev_hist_id, xhlock->hist_id)))
|
|
break;
|
|
|
|
prev_hist_id = xhlock->hist_id;
|
|
|
|
/*
|
|
* commit_xhlock() returns 0 with graph_lock already
|
|
* released if fail.
|
|
*/
|
|
if (!commit_xhlock(xlock, xhlock))
|
|
return;
|
|
}
|
|
}
|
|
|
|
graph_unlock();
|
|
}
|
|
|
|
void lock_commit_crosslock(struct lockdep_map *lock)
|
|
{
|
|
struct cross_lock *xlock;
|
|
unsigned long flags;
|
|
|
|
if (unlikely(!debug_locks || current->lockdep_recursion))
|
|
return;
|
|
|
|
if (!current->xhlocks)
|
|
return;
|
|
|
|
/*
|
|
* Do commit hist_locks with the cross_lock, only in case that
|
|
* the cross_lock could depend on acquisitions after that.
|
|
*
|
|
* For example, if the cross_lock does not have the 'check' flag
|
|
* then we don't need to check dependencies and commit for that.
|
|
* Just skip it. In that case, of course, the cross_lock does
|
|
* not depend on acquisitions ahead, either.
|
|
*
|
|
* WARNING: Don't do that in add_xlock() in advance. When an
|
|
* acquisition context is different from the commit context,
|
|
* invalid(skipped) cross_lock might be accessed.
|
|
*/
|
|
if (!depend_after(&((struct lockdep_map_cross *)lock)->xlock.hlock))
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
check_flags(flags);
|
|
current->lockdep_recursion = 1;
|
|
xlock = &((struct lockdep_map_cross *)lock)->xlock;
|
|
commit_xhlocks(xlock);
|
|
current->lockdep_recursion = 0;
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(lock_commit_crosslock);
|
|
|
|
/*
|
|
* Return: 0 - failure;
|
|
* 1 - crosslock, done;
|
|
* 2 - normal lock, continue to held_lock[] ops.
|
|
*/
|
|
static int lock_release_crosslock(struct lockdep_map *lock)
|
|
{
|
|
if (cross_lock(lock)) {
|
|
if (!graph_lock())
|
|
return 0;
|
|
((struct lockdep_map_cross *)lock)->xlock.nr_acquire--;
|
|
graph_unlock();
|
|
return 1;
|
|
}
|
|
return 2;
|
|
}
|
|
|
|
static void cross_init(struct lockdep_map *lock, int cross)
|
|
{
|
|
if (cross)
|
|
((struct lockdep_map_cross *)lock)->xlock.nr_acquire = 0;
|
|
|
|
lock->cross = cross;
|
|
|
|
/*
|
|
* Crossrelease assumes that the ring buffer size of xhlocks
|
|
* is aligned with power of 2. So force it on build.
|
|
*/
|
|
BUILD_BUG_ON(MAX_XHLOCKS_NR & (MAX_XHLOCKS_NR - 1));
|
|
}
|
|
|
|
void lockdep_init_task(struct task_struct *task)
|
|
{
|
|
int i;
|
|
|
|
task->xhlock_idx = UINT_MAX;
|
|
task->hist_id = 0;
|
|
|
|
for (i = 0; i < XHLOCK_CTX_NR; i++) {
|
|
task->xhlock_idx_hist[i] = UINT_MAX;
|
|
task->hist_id_save[i] = 0;
|
|
}
|
|
|
|
task->xhlocks = kzalloc(sizeof(struct hist_lock) * MAX_XHLOCKS_NR,
|
|
GFP_KERNEL);
|
|
}
|
|
|
|
void lockdep_free_task(struct task_struct *task)
|
|
{
|
|
if (task->xhlocks) {
|
|
void *tmp = task->xhlocks;
|
|
/* Diable crossrelease for current */
|
|
task->xhlocks = NULL;
|
|
kfree(tmp);
|
|
}
|
|
}
|
|
#endif
|