Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar: "The main changes in this cycle were: - documentation updates - miscellaneous fixes - minor reorganization of code - torture-test updates" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (30 commits) rcu: Correctly handle sparse possible cpus rcu: sysctl: Panic on RCU Stall rcu: Fix a typo in a comment rcu: Make call_rcu_tasks() tolerate first call with irqs disabled rcu: Disable TASKS_RCU for usermode Linux rcu: No ordering for rcu_assign_pointer() of NULL rcutorture: Fix error return code in rcu_perf_init() torture: Inflict default jitter rcuperf: Don't treat gp_exp mis-setting as a WARN rcutorture: Drop "-soundhw pcspkr" from x86 boot arguments rcutorture: Don't specify the cpu type of QEMU on PPC rcutorture: Make -soundhw a x86 specific option rcutorture: Use vmlinux as the fallback kernel image rcutorture/doc: Create initrd using dracut torture: Stop onoff task if there is only one cpu torture: Add starvation events to error summary torture: Break online and offline functions out of torture_onoff() torture: Forgive lengthy trace dumps and preemption torture: Remove CONFIG_RCU_TORTURE_TEST_RUNNABLE, simplify code torture: Simplify code, eliminate RCU_PERF_TEST_RUNNABLE ...
This commit is contained in:
commit
df00ccca72
|
@ -2391,6 +2391,41 @@ and <tt>RCU_NONIDLE()</tt> on the other while inspecting
|
|||
idle-loop code.
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Steven Rostedt supplied <tt>_rcuidle</tt> event tracing,
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which is used quite heavily in the idle loop.
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However, there are some restrictions on the code placed within
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<tt>RCU_NONIDLE()</tt>:
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<ol>
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<li> Blocking is prohibited.
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In practice, this is not a serious restriction given that idle
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tasks are prohibited from blocking to begin with.
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<li> Although nesting <tt>RCU_NONIDLE()</tt> is permited, they cannot
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nest indefinitely deeply.
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However, given that they can be nested on the order of a million
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deep, even on 32-bit systems, this should not be a serious
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restriction.
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This nesting limit would probably be reached long after the
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compiler OOMed or the stack overflowed.
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<li> Any code path that enters <tt>RCU_NONIDLE()</tt> must sequence
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out of that same <tt>RCU_NONIDLE()</tt>.
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For example, the following is grossly illegal:
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<blockquote>
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<pre>
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1 RCU_NONIDLE({
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2 do_something();
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3 goto bad_idea; /* BUG!!! */
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4 do_something_else();});
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5 bad_idea:
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</pre>
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</blockquote>
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<p>
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It is just as illegal to transfer control into the middle of
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<tt>RCU_NONIDLE()</tt>'s argument.
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Yes, in theory, you could transfer in as long as you also
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transferred out, but in practice you could also expect to get sharply
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worded review comments.
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</ol>
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<p>
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It is similarly socially unacceptable to interrupt an
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|
|
|
@ -49,7 +49,7 @@ rcupdate.rcu_task_stall_timeout
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This boot/sysfs parameter controls the RCU-tasks stall warning
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interval. A value of zero or less suppresses RCU-tasks stall
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warnings. A positive value sets the stall-warning interval
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in jiffies. An RCU-tasks stall warning starts wtih the line:
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in jiffies. An RCU-tasks stall warning starts with the line:
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INFO: rcu_tasks detected stalls on tasks:
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|
|
|
@ -5,6 +5,9 @@ to start learning about RCU:
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2. What is RCU? Part 2: Usage http://lwn.net/Articles/263130/
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3. RCU part 3: the RCU API http://lwn.net/Articles/264090/
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4. The RCU API, 2010 Edition http://lwn.net/Articles/418853/
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2010 Big API Table http://lwn.net/Articles/419086/
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5. The RCU API, 2014 Edition http://lwn.net/Articles/609904/
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2014 Big API Table http://lwn.net/Articles/609973/
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What is RCU?
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|
|
|
@ -58,6 +58,7 @@ show up in /proc/sys/kernel:
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- panic_on_stackoverflow
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- panic_on_unrecovered_nmi
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- panic_on_warn
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- panic_on_rcu_stall
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- perf_cpu_time_max_percent
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- perf_event_paranoid
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- perf_event_max_stack
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|
@ -618,6 +619,17 @@ a kernel rebuild when attempting to kdump at the location of a WARN().
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==============================================================
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panic_on_rcu_stall:
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When set to 1, calls panic() after RCU stall detection messages. This
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is useful to define the root cause of RCU stalls using a vmcore.
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0: do not panic() when RCU stall takes place, default behavior.
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1: panic() after printing RCU stall messages.
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==============================================================
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perf_cpu_time_max_percent:
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Hints to the kernel how much CPU time it should be allowed to
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|
|
|
@ -451,6 +451,7 @@ extern int panic_on_oops;
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extern int panic_on_unrecovered_nmi;
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extern int panic_on_io_nmi;
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extern int panic_on_warn;
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extern int sysctl_panic_on_rcu_stall;
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extern int sysctl_panic_on_stackoverflow;
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||||
extern bool crash_kexec_post_notifiers;
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|
|
|
@ -45,6 +45,7 @@
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#include <linux/bug.h>
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#include <linux/compiler.h>
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#include <linux/ktime.h>
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#include <linux/irqflags.h>
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||||
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#include <asm/barrier.h>
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||||
|
||||
|
@ -379,12 +380,13 @@ static inline void rcu_init_nohz(void)
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* in the inner idle loop.
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*
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||||
* This macro provides the way out: RCU_NONIDLE(do_something_with_RCU())
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||||
* will tell RCU that it needs to pay attending, invoke its argument
|
||||
* (in this example, a call to the do_something_with_RCU() function),
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||||
* will tell RCU that it needs to pay attention, invoke its argument
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||||
* (in this example, calling the do_something_with_RCU() function),
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||||
* and then tell RCU to go back to ignoring this CPU. It is permissible
|
||||
* to nest RCU_NONIDLE() wrappers, but the nesting level is currently
|
||||
* quite limited. If deeper nesting is required, it will be necessary
|
||||
* to adjust DYNTICK_TASK_NESTING_VALUE accordingly.
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* to nest RCU_NONIDLE() wrappers, but not indefinitely (but the limit is
|
||||
* on the order of a million or so, even on 32-bit systems). It is
|
||||
* not legal to block within RCU_NONIDLE(), nor is it permissible to
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* transfer control either into or out of RCU_NONIDLE()'s statement.
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*/
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#define RCU_NONIDLE(a) \
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do { \
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|
@ -649,7 +651,16 @@ static inline void rcu_preempt_sleep_check(void)
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|||
* please be careful when making changes to rcu_assign_pointer() and the
|
||||
* other macros that it invokes.
|
||||
*/
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||||
#define rcu_assign_pointer(p, v) smp_store_release(&p, RCU_INITIALIZER(v))
|
||||
#define rcu_assign_pointer(p, v) \
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||||
({ \
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||||
uintptr_t _r_a_p__v = (uintptr_t)(v); \
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||||
\
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||||
if (__builtin_constant_p(v) && (_r_a_p__v) == (uintptr_t)NULL) \
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||||
WRITE_ONCE((p), (typeof(p))(_r_a_p__v)); \
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else \
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||||
smp_store_release(&p, RCU_INITIALIZER((typeof(p))_r_a_p__v)); \
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||||
_r_a_p__v; \
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||||
})
|
||||
|
||||
/**
|
||||
* rcu_access_pointer() - fetch RCU pointer with no dereferencing
|
||||
|
|
|
@ -50,6 +50,10 @@
|
|||
do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! %s\n", torture_type, s); } while (0)
|
||||
|
||||
/* Definitions for online/offline exerciser. */
|
||||
bool torture_offline(int cpu, long *n_onl_attempts, long *n_onl_successes,
|
||||
unsigned long *sum_offl, int *min_onl, int *max_onl);
|
||||
bool torture_online(int cpu, long *n_onl_attempts, long *n_onl_successes,
|
||||
unsigned long *sum_onl, int *min_onl, int *max_onl);
|
||||
int torture_onoff_init(long ooholdoff, long oointerval);
|
||||
void torture_onoff_stats(void);
|
||||
bool torture_onoff_failures(void);
|
||||
|
|
|
@ -517,6 +517,7 @@ config SRCU
|
|||
config TASKS_RCU
|
||||
bool
|
||||
default n
|
||||
depends on !UML
|
||||
select SRCU
|
||||
help
|
||||
This option enables a task-based RCU implementation that uses
|
||||
|
|
|
@ -58,7 +58,7 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.vnet.ibm.com>");
|
|||
#define VERBOSE_PERFOUT_ERRSTRING(s) \
|
||||
do { if (verbose) pr_alert("%s" PERF_FLAG "!!! %s\n", perf_type, s); } while (0)
|
||||
|
||||
torture_param(bool, gp_exp, true, "Use expedited GP wait primitives");
|
||||
torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
|
||||
torture_param(int, holdoff, 10, "Holdoff time before test start (s)");
|
||||
torture_param(int, nreaders, -1, "Number of RCU reader threads");
|
||||
torture_param(int, nwriters, -1, "Number of RCU updater threads");
|
||||
|
@ -96,12 +96,7 @@ static int rcu_perf_writer_state;
|
|||
#define MAX_MEAS 10000
|
||||
#define MIN_MEAS 100
|
||||
|
||||
#if defined(MODULE) || defined(CONFIG_RCU_PERF_TEST_RUNNABLE)
|
||||
#define RCUPERF_RUNNABLE_INIT 1
|
||||
#else
|
||||
#define RCUPERF_RUNNABLE_INIT 0
|
||||
#endif
|
||||
static int perf_runnable = RCUPERF_RUNNABLE_INIT;
|
||||
static int perf_runnable = IS_ENABLED(MODULE);
|
||||
module_param(perf_runnable, int, 0444);
|
||||
MODULE_PARM_DESC(perf_runnable, "Start rcuperf at boot");
|
||||
|
||||
|
@ -363,8 +358,6 @@ rcu_perf_writer(void *arg)
|
|||
u64 *wdpp = writer_durations[me];
|
||||
|
||||
VERBOSE_PERFOUT_STRING("rcu_perf_writer task started");
|
||||
WARN_ON(rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp);
|
||||
WARN_ON(rcu_gp_is_normal() && gp_exp);
|
||||
WARN_ON(!wdpp);
|
||||
set_cpus_allowed_ptr(current, cpumask_of(me % nr_cpu_ids));
|
||||
sp.sched_priority = 1;
|
||||
|
@ -631,12 +624,24 @@ rcu_perf_init(void)
|
|||
firsterr = -ENOMEM;
|
||||
goto unwind;
|
||||
}
|
||||
if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp) {
|
||||
VERBOSE_PERFOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
|
||||
firsterr = -EINVAL;
|
||||
goto unwind;
|
||||
}
|
||||
if (rcu_gp_is_normal() && gp_exp) {
|
||||
VERBOSE_PERFOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
|
||||
firsterr = -EINVAL;
|
||||
goto unwind;
|
||||
}
|
||||
for (i = 0; i < nrealwriters; i++) {
|
||||
writer_durations[i] =
|
||||
kcalloc(MAX_MEAS, sizeof(*writer_durations[i]),
|
||||
GFP_KERNEL);
|
||||
if (!writer_durations[i])
|
||||
if (!writer_durations[i]) {
|
||||
firsterr = -ENOMEM;
|
||||
goto unwind;
|
||||
}
|
||||
firsterr = torture_create_kthread(rcu_perf_writer, (void *)i,
|
||||
writer_tasks[i]);
|
||||
if (firsterr)
|
||||
|
|
|
@ -182,12 +182,7 @@ static const char *rcu_torture_writer_state_getname(void)
|
|||
return rcu_torture_writer_state_names[i];
|
||||
}
|
||||
|
||||
#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
|
||||
#define RCUTORTURE_RUNNABLE_INIT 1
|
||||
#else
|
||||
#define RCUTORTURE_RUNNABLE_INIT 0
|
||||
#endif
|
||||
static int torture_runnable = RCUTORTURE_RUNNABLE_INIT;
|
||||
static int torture_runnable = IS_ENABLED(MODULE);
|
||||
module_param(torture_runnable, int, 0444);
|
||||
MODULE_PARM_DESC(torture_runnable, "Start rcutorture at boot");
|
||||
|
||||
|
@ -1476,7 +1471,7 @@ static int rcu_torture_barrier_cbs(void *arg)
|
|||
break;
|
||||
/*
|
||||
* The above smp_load_acquire() ensures barrier_phase load
|
||||
* is ordered before the folloiwng ->call().
|
||||
* is ordered before the following ->call().
|
||||
*/
|
||||
local_irq_disable(); /* Just to test no-irq call_rcu(). */
|
||||
cur_ops->call(&rcu, rcu_torture_barrier_cbf);
|
||||
|
|
|
@ -125,12 +125,14 @@ int rcu_num_lvls __read_mostly = RCU_NUM_LVLS;
|
|||
/* Number of rcu_nodes at specified level. */
|
||||
static int num_rcu_lvl[] = NUM_RCU_LVL_INIT;
|
||||
int rcu_num_nodes __read_mostly = NUM_RCU_NODES; /* Total # rcu_nodes in use. */
|
||||
/* panic() on RCU Stall sysctl. */
|
||||
int sysctl_panic_on_rcu_stall __read_mostly;
|
||||
|
||||
/*
|
||||
* The rcu_scheduler_active variable transitions from zero to one just
|
||||
* before the first task is spawned. So when this variable is zero, RCU
|
||||
* can assume that there is but one task, allowing RCU to (for example)
|
||||
* optimize synchronize_sched() to a simple barrier(). When this variable
|
||||
* optimize synchronize_rcu() to a simple barrier(). When this variable
|
||||
* is one, RCU must actually do all the hard work required to detect real
|
||||
* grace periods. This variable is also used to suppress boot-time false
|
||||
* positives from lockdep-RCU error checking.
|
||||
|
@ -159,6 +161,7 @@ static void invoke_rcu_core(void);
|
|||
static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp);
|
||||
static void rcu_report_exp_rdp(struct rcu_state *rsp,
|
||||
struct rcu_data *rdp, bool wake);
|
||||
static void sync_sched_exp_online_cleanup(int cpu);
|
||||
|
||||
/* rcuc/rcub kthread realtime priority */
|
||||
#ifdef CONFIG_RCU_KTHREAD_PRIO
|
||||
|
@ -1284,9 +1287,9 @@ static void rcu_dump_cpu_stacks(struct rcu_state *rsp)
|
|||
rcu_for_each_leaf_node(rsp, rnp) {
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
if (rnp->qsmask != 0) {
|
||||
for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++)
|
||||
if (rnp->qsmask & (1UL << cpu))
|
||||
dump_cpu_task(rnp->grplo + cpu);
|
||||
for_each_leaf_node_possible_cpu(rnp, cpu)
|
||||
if (rnp->qsmask & leaf_node_cpu_bit(rnp, cpu))
|
||||
dump_cpu_task(cpu);
|
||||
}
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
}
|
||||
|
@ -1311,6 +1314,12 @@ static void rcu_stall_kick_kthreads(struct rcu_state *rsp)
|
|||
}
|
||||
}
|
||||
|
||||
static inline void panic_on_rcu_stall(void)
|
||||
{
|
||||
if (sysctl_panic_on_rcu_stall)
|
||||
panic("RCU Stall\n");
|
||||
}
|
||||
|
||||
static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
|
||||
{
|
||||
int cpu;
|
||||
|
@ -1351,10 +1360,9 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
|
|||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
ndetected += rcu_print_task_stall(rnp);
|
||||
if (rnp->qsmask != 0) {
|
||||
for (cpu = 0; cpu <= rnp->grphi - rnp->grplo; cpu++)
|
||||
if (rnp->qsmask & (1UL << cpu)) {
|
||||
print_cpu_stall_info(rsp,
|
||||
rnp->grplo + cpu);
|
||||
for_each_leaf_node_possible_cpu(rnp, cpu)
|
||||
if (rnp->qsmask & leaf_node_cpu_bit(rnp, cpu)) {
|
||||
print_cpu_stall_info(rsp, cpu);
|
||||
ndetected++;
|
||||
}
|
||||
}
|
||||
|
@ -1390,6 +1398,8 @@ static void print_other_cpu_stall(struct rcu_state *rsp, unsigned long gpnum)
|
|||
|
||||
rcu_check_gp_kthread_starvation(rsp);
|
||||
|
||||
panic_on_rcu_stall();
|
||||
|
||||
force_quiescent_state(rsp); /* Kick them all. */
|
||||
}
|
||||
|
||||
|
@ -1430,6 +1440,8 @@ static void print_cpu_stall(struct rcu_state *rsp)
|
|||
jiffies + 3 * rcu_jiffies_till_stall_check() + 3);
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
|
||||
panic_on_rcu_stall();
|
||||
|
||||
/*
|
||||
* Attempt to revive the RCU machinery by forcing a context switch.
|
||||
*
|
||||
|
@ -1989,8 +2001,7 @@ static bool rcu_gp_init(struct rcu_state *rsp)
|
|||
* of the tree within the rsp->node[] array. Note that other CPUs
|
||||
* will access only the leaves of the hierarchy, thus seeing that no
|
||||
* grace period is in progress, at least until the corresponding
|
||||
* leaf node has been initialized. In addition, we have excluded
|
||||
* CPU-hotplug operations.
|
||||
* leaf node has been initialized.
|
||||
*
|
||||
* The grace period cannot complete until the initialization
|
||||
* process finishes, because this kthread handles both.
|
||||
|
@ -2872,7 +2883,6 @@ static void force_qs_rnp(struct rcu_state *rsp,
|
|||
unsigned long *maxj),
|
||||
bool *isidle, unsigned long *maxj)
|
||||
{
|
||||
unsigned long bit;
|
||||
int cpu;
|
||||
unsigned long flags;
|
||||
unsigned long mask;
|
||||
|
@ -2907,9 +2917,8 @@ static void force_qs_rnp(struct rcu_state *rsp,
|
|||
continue;
|
||||
}
|
||||
}
|
||||
cpu = rnp->grplo;
|
||||
bit = 1;
|
||||
for (; cpu <= rnp->grphi; cpu++, bit <<= 1) {
|
||||
for_each_leaf_node_possible_cpu(rnp, cpu) {
|
||||
unsigned long bit = leaf_node_cpu_bit(rnp, cpu);
|
||||
if ((rnp->qsmask & bit) != 0) {
|
||||
if (f(per_cpu_ptr(rsp->rda, cpu), isidle, maxj))
|
||||
mask |= bit;
|
||||
|
@ -3448,549 +3457,6 @@ static bool rcu_seq_done(unsigned long *sp, unsigned long s)
|
|||
return ULONG_CMP_GE(READ_ONCE(*sp), s);
|
||||
}
|
||||
|
||||
/* Wrapper functions for expedited grace periods. */
|
||||
static void rcu_exp_gp_seq_start(struct rcu_state *rsp)
|
||||
{
|
||||
rcu_seq_start(&rsp->expedited_sequence);
|
||||
}
|
||||
static void rcu_exp_gp_seq_end(struct rcu_state *rsp)
|
||||
{
|
||||
rcu_seq_end(&rsp->expedited_sequence);
|
||||
smp_mb(); /* Ensure that consecutive grace periods serialize. */
|
||||
}
|
||||
static unsigned long rcu_exp_gp_seq_snap(struct rcu_state *rsp)
|
||||
{
|
||||
unsigned long s;
|
||||
|
||||
smp_mb(); /* Caller's modifications seen first by other CPUs. */
|
||||
s = rcu_seq_snap(&rsp->expedited_sequence);
|
||||
trace_rcu_exp_grace_period(rsp->name, s, TPS("snap"));
|
||||
return s;
|
||||
}
|
||||
static bool rcu_exp_gp_seq_done(struct rcu_state *rsp, unsigned long s)
|
||||
{
|
||||
return rcu_seq_done(&rsp->expedited_sequence, s);
|
||||
}
|
||||
|
||||
/*
|
||||
* Reset the ->expmaskinit values in the rcu_node tree to reflect any
|
||||
* recent CPU-online activity. Note that these masks are not cleared
|
||||
* when CPUs go offline, so they reflect the union of all CPUs that have
|
||||
* ever been online. This means that this function normally takes its
|
||||
* no-work-to-do fastpath.
|
||||
*/
|
||||
static void sync_exp_reset_tree_hotplug(struct rcu_state *rsp)
|
||||
{
|
||||
bool done;
|
||||
unsigned long flags;
|
||||
unsigned long mask;
|
||||
unsigned long oldmask;
|
||||
int ncpus = READ_ONCE(rsp->ncpus);
|
||||
struct rcu_node *rnp;
|
||||
struct rcu_node *rnp_up;
|
||||
|
||||
/* If no new CPUs onlined since last time, nothing to do. */
|
||||
if (likely(ncpus == rsp->ncpus_snap))
|
||||
return;
|
||||
rsp->ncpus_snap = ncpus;
|
||||
|
||||
/*
|
||||
* Each pass through the following loop propagates newly onlined
|
||||
* CPUs for the current rcu_node structure up the rcu_node tree.
|
||||
*/
|
||||
rcu_for_each_leaf_node(rsp, rnp) {
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
if (rnp->expmaskinit == rnp->expmaskinitnext) {
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
continue; /* No new CPUs, nothing to do. */
|
||||
}
|
||||
|
||||
/* Update this node's mask, track old value for propagation. */
|
||||
oldmask = rnp->expmaskinit;
|
||||
rnp->expmaskinit = rnp->expmaskinitnext;
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
|
||||
/* If was already nonzero, nothing to propagate. */
|
||||
if (oldmask)
|
||||
continue;
|
||||
|
||||
/* Propagate the new CPU up the tree. */
|
||||
mask = rnp->grpmask;
|
||||
rnp_up = rnp->parent;
|
||||
done = false;
|
||||
while (rnp_up) {
|
||||
raw_spin_lock_irqsave_rcu_node(rnp_up, flags);
|
||||
if (rnp_up->expmaskinit)
|
||||
done = true;
|
||||
rnp_up->expmaskinit |= mask;
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp_up, flags);
|
||||
if (done)
|
||||
break;
|
||||
mask = rnp_up->grpmask;
|
||||
rnp_up = rnp_up->parent;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Reset the ->expmask values in the rcu_node tree in preparation for
|
||||
* a new expedited grace period.
|
||||
*/
|
||||
static void __maybe_unused sync_exp_reset_tree(struct rcu_state *rsp)
|
||||
{
|
||||
unsigned long flags;
|
||||
struct rcu_node *rnp;
|
||||
|
||||
sync_exp_reset_tree_hotplug(rsp);
|
||||
rcu_for_each_node_breadth_first(rsp, rnp) {
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
WARN_ON_ONCE(rnp->expmask);
|
||||
rnp->expmask = rnp->expmaskinit;
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Return non-zero if there is no RCU expedited grace period in progress
|
||||
* for the specified rcu_node structure, in other words, if all CPUs and
|
||||
* tasks covered by the specified rcu_node structure have done their bit
|
||||
* for the current expedited grace period. Works only for preemptible
|
||||
* RCU -- other RCU implementation use other means.
|
||||
*
|
||||
* Caller must hold the rcu_state's exp_mutex.
|
||||
*/
|
||||
static int sync_rcu_preempt_exp_done(struct rcu_node *rnp)
|
||||
{
|
||||
return rnp->exp_tasks == NULL &&
|
||||
READ_ONCE(rnp->expmask) == 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* Report the exit from RCU read-side critical section for the last task
|
||||
* that queued itself during or before the current expedited preemptible-RCU
|
||||
* grace period. This event is reported either to the rcu_node structure on
|
||||
* which the task was queued or to one of that rcu_node structure's ancestors,
|
||||
* recursively up the tree. (Calm down, calm down, we do the recursion
|
||||
* iteratively!)
|
||||
*
|
||||
* Caller must hold the rcu_state's exp_mutex and the specified rcu_node
|
||||
* structure's ->lock.
|
||||
*/
|
||||
static void __rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
|
||||
bool wake, unsigned long flags)
|
||||
__releases(rnp->lock)
|
||||
{
|
||||
unsigned long mask;
|
||||
|
||||
for (;;) {
|
||||
if (!sync_rcu_preempt_exp_done(rnp)) {
|
||||
if (!rnp->expmask)
|
||||
rcu_initiate_boost(rnp, flags);
|
||||
else
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
break;
|
||||
}
|
||||
if (rnp->parent == NULL) {
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
if (wake) {
|
||||
smp_mb(); /* EGP done before wake_up(). */
|
||||
swake_up(&rsp->expedited_wq);
|
||||
}
|
||||
break;
|
||||
}
|
||||
mask = rnp->grpmask;
|
||||
raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled */
|
||||
rnp = rnp->parent;
|
||||
raw_spin_lock_rcu_node(rnp); /* irqs already disabled */
|
||||
WARN_ON_ONCE(!(rnp->expmask & mask));
|
||||
rnp->expmask &= ~mask;
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Report expedited quiescent state for specified node. This is a
|
||||
* lock-acquisition wrapper function for __rcu_report_exp_rnp().
|
||||
*
|
||||
* Caller must hold the rcu_state's exp_mutex.
|
||||
*/
|
||||
static void __maybe_unused rcu_report_exp_rnp(struct rcu_state *rsp,
|
||||
struct rcu_node *rnp, bool wake)
|
||||
{
|
||||
unsigned long flags;
|
||||
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
__rcu_report_exp_rnp(rsp, rnp, wake, flags);
|
||||
}
|
||||
|
||||
/*
|
||||
* Report expedited quiescent state for multiple CPUs, all covered by the
|
||||
* specified leaf rcu_node structure. Caller must hold the rcu_state's
|
||||
* exp_mutex.
|
||||
*/
|
||||
static void rcu_report_exp_cpu_mult(struct rcu_state *rsp, struct rcu_node *rnp,
|
||||
unsigned long mask, bool wake)
|
||||
{
|
||||
unsigned long flags;
|
||||
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
if (!(rnp->expmask & mask)) {
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
return;
|
||||
}
|
||||
rnp->expmask &= ~mask;
|
||||
__rcu_report_exp_rnp(rsp, rnp, wake, flags); /* Releases rnp->lock. */
|
||||
}
|
||||
|
||||
/*
|
||||
* Report expedited quiescent state for specified rcu_data (CPU).
|
||||
*/
|
||||
static void rcu_report_exp_rdp(struct rcu_state *rsp, struct rcu_data *rdp,
|
||||
bool wake)
|
||||
{
|
||||
rcu_report_exp_cpu_mult(rsp, rdp->mynode, rdp->grpmask, wake);
|
||||
}
|
||||
|
||||
/* Common code for synchronize_{rcu,sched}_expedited() work-done checking. */
|
||||
static bool sync_exp_work_done(struct rcu_state *rsp, atomic_long_t *stat,
|
||||
unsigned long s)
|
||||
{
|
||||
if (rcu_exp_gp_seq_done(rsp, s)) {
|
||||
trace_rcu_exp_grace_period(rsp->name, s, TPS("done"));
|
||||
/* Ensure test happens before caller kfree(). */
|
||||
smp_mb__before_atomic(); /* ^^^ */
|
||||
atomic_long_inc(stat);
|
||||
return true;
|
||||
}
|
||||
return false;
|
||||
}
|
||||
|
||||
/*
|
||||
* Funnel-lock acquisition for expedited grace periods. Returns true
|
||||
* if some other task completed an expedited grace period that this task
|
||||
* can piggy-back on, and with no mutex held. Otherwise, returns false
|
||||
* with the mutex held, indicating that the caller must actually do the
|
||||
* expedited grace period.
|
||||
*/
|
||||
static bool exp_funnel_lock(struct rcu_state *rsp, unsigned long s)
|
||||
{
|
||||
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, raw_smp_processor_id());
|
||||
struct rcu_node *rnp = rdp->mynode;
|
||||
struct rcu_node *rnp_root = rcu_get_root(rsp);
|
||||
|
||||
/* Low-contention fastpath. */
|
||||
if (ULONG_CMP_LT(READ_ONCE(rnp->exp_seq_rq), s) &&
|
||||
(rnp == rnp_root ||
|
||||
ULONG_CMP_LT(READ_ONCE(rnp_root->exp_seq_rq), s)) &&
|
||||
!mutex_is_locked(&rsp->exp_mutex) &&
|
||||
mutex_trylock(&rsp->exp_mutex))
|
||||
goto fastpath;
|
||||
|
||||
/*
|
||||
* Each pass through the following loop works its way up
|
||||
* the rcu_node tree, returning if others have done the work or
|
||||
* otherwise falls through to acquire rsp->exp_mutex. The mapping
|
||||
* from CPU to rcu_node structure can be inexact, as it is just
|
||||
* promoting locality and is not strictly needed for correctness.
|
||||
*/
|
||||
for (; rnp != NULL; rnp = rnp->parent) {
|
||||
if (sync_exp_work_done(rsp, &rdp->exp_workdone1, s))
|
||||
return true;
|
||||
|
||||
/* Work not done, either wait here or go up. */
|
||||
spin_lock(&rnp->exp_lock);
|
||||
if (ULONG_CMP_GE(rnp->exp_seq_rq, s)) {
|
||||
|
||||
/* Someone else doing GP, so wait for them. */
|
||||
spin_unlock(&rnp->exp_lock);
|
||||
trace_rcu_exp_funnel_lock(rsp->name, rnp->level,
|
||||
rnp->grplo, rnp->grphi,
|
||||
TPS("wait"));
|
||||
wait_event(rnp->exp_wq[(s >> 1) & 0x3],
|
||||
sync_exp_work_done(rsp,
|
||||
&rdp->exp_workdone2, s));
|
||||
return true;
|
||||
}
|
||||
rnp->exp_seq_rq = s; /* Followers can wait on us. */
|
||||
spin_unlock(&rnp->exp_lock);
|
||||
trace_rcu_exp_funnel_lock(rsp->name, rnp->level, rnp->grplo,
|
||||
rnp->grphi, TPS("nxtlvl"));
|
||||
}
|
||||
mutex_lock(&rsp->exp_mutex);
|
||||
fastpath:
|
||||
if (sync_exp_work_done(rsp, &rdp->exp_workdone3, s)) {
|
||||
mutex_unlock(&rsp->exp_mutex);
|
||||
return true;
|
||||
}
|
||||
rcu_exp_gp_seq_start(rsp);
|
||||
trace_rcu_exp_grace_period(rsp->name, s, TPS("start"));
|
||||
return false;
|
||||
}
|
||||
|
||||
/* Invoked on each online non-idle CPU for expedited quiescent state. */
|
||||
static void sync_sched_exp_handler(void *data)
|
||||
{
|
||||
struct rcu_data *rdp;
|
||||
struct rcu_node *rnp;
|
||||
struct rcu_state *rsp = data;
|
||||
|
||||
rdp = this_cpu_ptr(rsp->rda);
|
||||
rnp = rdp->mynode;
|
||||
if (!(READ_ONCE(rnp->expmask) & rdp->grpmask) ||
|
||||
__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp))
|
||||
return;
|
||||
if (rcu_is_cpu_rrupt_from_idle()) {
|
||||
rcu_report_exp_rdp(&rcu_sched_state,
|
||||
this_cpu_ptr(&rcu_sched_data), true);
|
||||
return;
|
||||
}
|
||||
__this_cpu_write(rcu_sched_data.cpu_no_qs.b.exp, true);
|
||||
resched_cpu(smp_processor_id());
|
||||
}
|
||||
|
||||
/* Send IPI for expedited cleanup if needed at end of CPU-hotplug operation. */
|
||||
static void sync_sched_exp_online_cleanup(int cpu)
|
||||
{
|
||||
struct rcu_data *rdp;
|
||||
int ret;
|
||||
struct rcu_node *rnp;
|
||||
struct rcu_state *rsp = &rcu_sched_state;
|
||||
|
||||
rdp = per_cpu_ptr(rsp->rda, cpu);
|
||||
rnp = rdp->mynode;
|
||||
if (!(READ_ONCE(rnp->expmask) & rdp->grpmask))
|
||||
return;
|
||||
ret = smp_call_function_single(cpu, sync_sched_exp_handler, rsp, 0);
|
||||
WARN_ON_ONCE(ret);
|
||||
}
|
||||
|
||||
/*
|
||||
* Select the nodes that the upcoming expedited grace period needs
|
||||
* to wait for.
|
||||
*/
|
||||
static void sync_rcu_exp_select_cpus(struct rcu_state *rsp,
|
||||
smp_call_func_t func)
|
||||
{
|
||||
int cpu;
|
||||
unsigned long flags;
|
||||
unsigned long mask;
|
||||
unsigned long mask_ofl_test;
|
||||
unsigned long mask_ofl_ipi;
|
||||
int ret;
|
||||
struct rcu_node *rnp;
|
||||
|
||||
sync_exp_reset_tree(rsp);
|
||||
rcu_for_each_leaf_node(rsp, rnp) {
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
|
||||
/* Each pass checks a CPU for identity, offline, and idle. */
|
||||
mask_ofl_test = 0;
|
||||
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++) {
|
||||
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
|
||||
struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
|
||||
|
||||
if (raw_smp_processor_id() == cpu ||
|
||||
!(atomic_add_return(0, &rdtp->dynticks) & 0x1))
|
||||
mask_ofl_test |= rdp->grpmask;
|
||||
}
|
||||
mask_ofl_ipi = rnp->expmask & ~mask_ofl_test;
|
||||
|
||||
/*
|
||||
* Need to wait for any blocked tasks as well. Note that
|
||||
* additional blocking tasks will also block the expedited
|
||||
* GP until such time as the ->expmask bits are cleared.
|
||||
*/
|
||||
if (rcu_preempt_has_tasks(rnp))
|
||||
rnp->exp_tasks = rnp->blkd_tasks.next;
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
|
||||
/* IPI the remaining CPUs for expedited quiescent state. */
|
||||
mask = 1;
|
||||
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) {
|
||||
if (!(mask_ofl_ipi & mask))
|
||||
continue;
|
||||
retry_ipi:
|
||||
ret = smp_call_function_single(cpu, func, rsp, 0);
|
||||
if (!ret) {
|
||||
mask_ofl_ipi &= ~mask;
|
||||
continue;
|
||||
}
|
||||
/* Failed, raced with offline. */
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
if (cpu_online(cpu) &&
|
||||
(rnp->expmask & mask)) {
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
schedule_timeout_uninterruptible(1);
|
||||
if (cpu_online(cpu) &&
|
||||
(rnp->expmask & mask))
|
||||
goto retry_ipi;
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
}
|
||||
if (!(rnp->expmask & mask))
|
||||
mask_ofl_ipi &= ~mask;
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
}
|
||||
/* Report quiescent states for those that went offline. */
|
||||
mask_ofl_test |= mask_ofl_ipi;
|
||||
if (mask_ofl_test)
|
||||
rcu_report_exp_cpu_mult(rsp, rnp, mask_ofl_test, false);
|
||||
}
|
||||
}
|
||||
|
||||
static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
|
||||
{
|
||||
int cpu;
|
||||
unsigned long jiffies_stall;
|
||||
unsigned long jiffies_start;
|
||||
unsigned long mask;
|
||||
int ndetected;
|
||||
struct rcu_node *rnp;
|
||||
struct rcu_node *rnp_root = rcu_get_root(rsp);
|
||||
int ret;
|
||||
|
||||
jiffies_stall = rcu_jiffies_till_stall_check();
|
||||
jiffies_start = jiffies;
|
||||
|
||||
for (;;) {
|
||||
ret = swait_event_timeout(
|
||||
rsp->expedited_wq,
|
||||
sync_rcu_preempt_exp_done(rnp_root),
|
||||
jiffies_stall);
|
||||
if (ret > 0 || sync_rcu_preempt_exp_done(rnp_root))
|
||||
return;
|
||||
if (ret < 0) {
|
||||
/* Hit a signal, disable CPU stall warnings. */
|
||||
swait_event(rsp->expedited_wq,
|
||||
sync_rcu_preempt_exp_done(rnp_root));
|
||||
return;
|
||||
}
|
||||
pr_err("INFO: %s detected expedited stalls on CPUs/tasks: {",
|
||||
rsp->name);
|
||||
ndetected = 0;
|
||||
rcu_for_each_leaf_node(rsp, rnp) {
|
||||
ndetected += rcu_print_task_exp_stall(rnp);
|
||||
mask = 1;
|
||||
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) {
|
||||
struct rcu_data *rdp;
|
||||
|
||||
if (!(rnp->expmask & mask))
|
||||
continue;
|
||||
ndetected++;
|
||||
rdp = per_cpu_ptr(rsp->rda, cpu);
|
||||
pr_cont(" %d-%c%c%c", cpu,
|
||||
"O."[!!cpu_online(cpu)],
|
||||
"o."[!!(rdp->grpmask & rnp->expmaskinit)],
|
||||
"N."[!!(rdp->grpmask & rnp->expmaskinitnext)]);
|
||||
}
|
||||
mask <<= 1;
|
||||
}
|
||||
pr_cont(" } %lu jiffies s: %lu root: %#lx/%c\n",
|
||||
jiffies - jiffies_start, rsp->expedited_sequence,
|
||||
rnp_root->expmask, ".T"[!!rnp_root->exp_tasks]);
|
||||
if (ndetected) {
|
||||
pr_err("blocking rcu_node structures:");
|
||||
rcu_for_each_node_breadth_first(rsp, rnp) {
|
||||
if (rnp == rnp_root)
|
||||
continue; /* printed unconditionally */
|
||||
if (sync_rcu_preempt_exp_done(rnp))
|
||||
continue;
|
||||
pr_cont(" l=%u:%d-%d:%#lx/%c",
|
||||
rnp->level, rnp->grplo, rnp->grphi,
|
||||
rnp->expmask,
|
||||
".T"[!!rnp->exp_tasks]);
|
||||
}
|
||||
pr_cont("\n");
|
||||
}
|
||||
rcu_for_each_leaf_node(rsp, rnp) {
|
||||
mask = 1;
|
||||
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask <<= 1) {
|
||||
if (!(rnp->expmask & mask))
|
||||
continue;
|
||||
dump_cpu_task(cpu);
|
||||
}
|
||||
}
|
||||
jiffies_stall = 3 * rcu_jiffies_till_stall_check() + 3;
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Wait for the current expedited grace period to complete, and then
|
||||
* wake up everyone who piggybacked on the just-completed expedited
|
||||
* grace period. Also update all the ->exp_seq_rq counters as needed
|
||||
* in order to avoid counter-wrap problems.
|
||||
*/
|
||||
static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s)
|
||||
{
|
||||
struct rcu_node *rnp;
|
||||
|
||||
synchronize_sched_expedited_wait(rsp);
|
||||
rcu_exp_gp_seq_end(rsp);
|
||||
trace_rcu_exp_grace_period(rsp->name, s, TPS("end"));
|
||||
|
||||
/*
|
||||
* Switch over to wakeup mode, allowing the next GP, but -only- the
|
||||
* next GP, to proceed.
|
||||
*/
|
||||
mutex_lock(&rsp->exp_wake_mutex);
|
||||
mutex_unlock(&rsp->exp_mutex);
|
||||
|
||||
rcu_for_each_node_breadth_first(rsp, rnp) {
|
||||
if (ULONG_CMP_LT(READ_ONCE(rnp->exp_seq_rq), s)) {
|
||||
spin_lock(&rnp->exp_lock);
|
||||
/* Recheck, avoid hang in case someone just arrived. */
|
||||
if (ULONG_CMP_LT(rnp->exp_seq_rq, s))
|
||||
rnp->exp_seq_rq = s;
|
||||
spin_unlock(&rnp->exp_lock);
|
||||
}
|
||||
wake_up_all(&rnp->exp_wq[(rsp->expedited_sequence >> 1) & 0x3]);
|
||||
}
|
||||
trace_rcu_exp_grace_period(rsp->name, s, TPS("endwake"));
|
||||
mutex_unlock(&rsp->exp_wake_mutex);
|
||||
}
|
||||
|
||||
/**
|
||||
* synchronize_sched_expedited - Brute-force RCU-sched grace period
|
||||
*
|
||||
* Wait for an RCU-sched grace period to elapse, but use a "big hammer"
|
||||
* approach to force the grace period to end quickly. This consumes
|
||||
* significant time on all CPUs and is unfriendly to real-time workloads,
|
||||
* so is thus not recommended for any sort of common-case code. In fact,
|
||||
* if you are using synchronize_sched_expedited() in a loop, please
|
||||
* restructure your code to batch your updates, and then use a single
|
||||
* synchronize_sched() instead.
|
||||
*
|
||||
* This implementation can be thought of as an application of sequence
|
||||
* locking to expedited grace periods, but using the sequence counter to
|
||||
* determine when someone else has already done the work instead of for
|
||||
* retrying readers.
|
||||
*/
|
||||
void synchronize_sched_expedited(void)
|
||||
{
|
||||
unsigned long s;
|
||||
struct rcu_state *rsp = &rcu_sched_state;
|
||||
|
||||
/* If only one CPU, this is automatically a grace period. */
|
||||
if (rcu_blocking_is_gp())
|
||||
return;
|
||||
|
||||
/* If expedited grace periods are prohibited, fall back to normal. */
|
||||
if (rcu_gp_is_normal()) {
|
||||
wait_rcu_gp(call_rcu_sched);
|
||||
return;
|
||||
}
|
||||
|
||||
/* Take a snapshot of the sequence number. */
|
||||
s = rcu_exp_gp_seq_snap(rsp);
|
||||
if (exp_funnel_lock(rsp, s))
|
||||
return; /* Someone else did our work for us. */
|
||||
|
||||
/* Initialize the rcu_node tree in preparation for the wait. */
|
||||
sync_rcu_exp_select_cpus(rsp, sync_sched_exp_handler);
|
||||
|
||||
/* Wait and clean up, including waking everyone. */
|
||||
rcu_exp_wait_wake(rsp, s);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
|
||||
|
||||
/*
|
||||
* Check to see if there is any immediate RCU-related work to be done
|
||||
* by the current CPU, for the specified type of RCU, returning 1 if so.
|
||||
|
@ -4281,7 +3747,7 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
|
|||
|
||||
/* Set up local state, ensuring consistent view of global state. */
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
|
||||
rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu);
|
||||
rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
|
||||
WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_EXIT_IDLE);
|
||||
WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1);
|
||||
|
@ -4364,9 +3830,6 @@ static void rcu_cleanup_dying_idle_cpu(int cpu, struct rcu_state *rsp)
|
|||
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
|
||||
struct rcu_node *rnp = rdp->mynode; /* Outgoing CPU's rdp & rnp. */
|
||||
|
||||
if (!IS_ENABLED(CONFIG_HOTPLUG_CPU))
|
||||
return;
|
||||
|
||||
/* Remove outgoing CPU from mask in the leaf rcu_node structure. */
|
||||
mask = rdp->grpmask;
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags); /* Enforce GP memory-order guarantee. */
|
||||
|
@ -4751,4 +4214,5 @@ void __init rcu_init(void)
|
|||
rcu_cpu_notify(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
|
||||
}
|
||||
|
||||
#include "tree_exp.h"
|
||||
#include "tree_plugin.h"
|
||||
|
|
|
@ -253,6 +253,13 @@ struct rcu_node {
|
|||
wait_queue_head_t exp_wq[4];
|
||||
} ____cacheline_internodealigned_in_smp;
|
||||
|
||||
/*
|
||||
* Bitmasks in an rcu_node cover the interval [grplo, grphi] of CPU IDs, and
|
||||
* are indexed relative to this interval rather than the global CPU ID space.
|
||||
* This generates the bit for a CPU in node-local masks.
|
||||
*/
|
||||
#define leaf_node_cpu_bit(rnp, cpu) (1UL << ((cpu) - (rnp)->grplo))
|
||||
|
||||
/*
|
||||
* Do a full breadth-first scan of the rcu_node structures for the
|
||||
* specified rcu_state structure.
|
||||
|
@ -280,6 +287,14 @@ struct rcu_node {
|
|||
for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \
|
||||
(rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
|
||||
|
||||
/*
|
||||
* Iterate over all possible CPUs in a leaf RCU node.
|
||||
*/
|
||||
#define for_each_leaf_node_possible_cpu(rnp, cpu) \
|
||||
for ((cpu) = cpumask_next(rnp->grplo - 1, cpu_possible_mask); \
|
||||
cpu <= rnp->grphi; \
|
||||
cpu = cpumask_next((cpu), cpu_possible_mask))
|
||||
|
||||
/*
|
||||
* Union to allow "aggregate OR" operation on the need for a quiescent
|
||||
* state by the normal and expedited grace periods.
|
||||
|
|
656
kernel/rcu/tree_exp.h
Normal file
656
kernel/rcu/tree_exp.h
Normal file
|
@ -0,0 +1,656 @@
|
|||
/*
|
||||
* RCU expedited grace periods
|
||||
*
|
||||
* This program is free software; you can redistribute it and/or modify
|
||||
* it under the terms of the GNU General Public License as published by
|
||||
* the Free Software Foundation; either version 2 of the License, or
|
||||
* (at your option) any later version.
|
||||
*
|
||||
* This program is distributed in the hope that it will be useful,
|
||||
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
* GNU General Public License for more details.
|
||||
*
|
||||
* You should have received a copy of the GNU General Public License
|
||||
* along with this program; if not, you can access it online at
|
||||
* http://www.gnu.org/licenses/gpl-2.0.html.
|
||||
*
|
||||
* Copyright IBM Corporation, 2016
|
||||
*
|
||||
* Authors: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
|
||||
*/
|
||||
|
||||
/* Wrapper functions for expedited grace periods. */
|
||||
static void rcu_exp_gp_seq_start(struct rcu_state *rsp)
|
||||
{
|
||||
rcu_seq_start(&rsp->expedited_sequence);
|
||||
}
|
||||
static void rcu_exp_gp_seq_end(struct rcu_state *rsp)
|
||||
{
|
||||
rcu_seq_end(&rsp->expedited_sequence);
|
||||
smp_mb(); /* Ensure that consecutive grace periods serialize. */
|
||||
}
|
||||
static unsigned long rcu_exp_gp_seq_snap(struct rcu_state *rsp)
|
||||
{
|
||||
unsigned long s;
|
||||
|
||||
smp_mb(); /* Caller's modifications seen first by other CPUs. */
|
||||
s = rcu_seq_snap(&rsp->expedited_sequence);
|
||||
trace_rcu_exp_grace_period(rsp->name, s, TPS("snap"));
|
||||
return s;
|
||||
}
|
||||
static bool rcu_exp_gp_seq_done(struct rcu_state *rsp, unsigned long s)
|
||||
{
|
||||
return rcu_seq_done(&rsp->expedited_sequence, s);
|
||||
}
|
||||
|
||||
/*
|
||||
* Reset the ->expmaskinit values in the rcu_node tree to reflect any
|
||||
* recent CPU-online activity. Note that these masks are not cleared
|
||||
* when CPUs go offline, so they reflect the union of all CPUs that have
|
||||
* ever been online. This means that this function normally takes its
|
||||
* no-work-to-do fastpath.
|
||||
*/
|
||||
static void sync_exp_reset_tree_hotplug(struct rcu_state *rsp)
|
||||
{
|
||||
bool done;
|
||||
unsigned long flags;
|
||||
unsigned long mask;
|
||||
unsigned long oldmask;
|
||||
int ncpus = READ_ONCE(rsp->ncpus);
|
||||
struct rcu_node *rnp;
|
||||
struct rcu_node *rnp_up;
|
||||
|
||||
/* If no new CPUs onlined since last time, nothing to do. */
|
||||
if (likely(ncpus == rsp->ncpus_snap))
|
||||
return;
|
||||
rsp->ncpus_snap = ncpus;
|
||||
|
||||
/*
|
||||
* Each pass through the following loop propagates newly onlined
|
||||
* CPUs for the current rcu_node structure up the rcu_node tree.
|
||||
*/
|
||||
rcu_for_each_leaf_node(rsp, rnp) {
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
if (rnp->expmaskinit == rnp->expmaskinitnext) {
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
continue; /* No new CPUs, nothing to do. */
|
||||
}
|
||||
|
||||
/* Update this node's mask, track old value for propagation. */
|
||||
oldmask = rnp->expmaskinit;
|
||||
rnp->expmaskinit = rnp->expmaskinitnext;
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
|
||||
/* If was already nonzero, nothing to propagate. */
|
||||
if (oldmask)
|
||||
continue;
|
||||
|
||||
/* Propagate the new CPU up the tree. */
|
||||
mask = rnp->grpmask;
|
||||
rnp_up = rnp->parent;
|
||||
done = false;
|
||||
while (rnp_up) {
|
||||
raw_spin_lock_irqsave_rcu_node(rnp_up, flags);
|
||||
if (rnp_up->expmaskinit)
|
||||
done = true;
|
||||
rnp_up->expmaskinit |= mask;
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp_up, flags);
|
||||
if (done)
|
||||
break;
|
||||
mask = rnp_up->grpmask;
|
||||
rnp_up = rnp_up->parent;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Reset the ->expmask values in the rcu_node tree in preparation for
|
||||
* a new expedited grace period.
|
||||
*/
|
||||
static void __maybe_unused sync_exp_reset_tree(struct rcu_state *rsp)
|
||||
{
|
||||
unsigned long flags;
|
||||
struct rcu_node *rnp;
|
||||
|
||||
sync_exp_reset_tree_hotplug(rsp);
|
||||
rcu_for_each_node_breadth_first(rsp, rnp) {
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
WARN_ON_ONCE(rnp->expmask);
|
||||
rnp->expmask = rnp->expmaskinit;
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Return non-zero if there is no RCU expedited grace period in progress
|
||||
* for the specified rcu_node structure, in other words, if all CPUs and
|
||||
* tasks covered by the specified rcu_node structure have done their bit
|
||||
* for the current expedited grace period. Works only for preemptible
|
||||
* RCU -- other RCU implementation use other means.
|
||||
*
|
||||
* Caller must hold the rcu_state's exp_mutex.
|
||||
*/
|
||||
static int sync_rcu_preempt_exp_done(struct rcu_node *rnp)
|
||||
{
|
||||
return rnp->exp_tasks == NULL &&
|
||||
READ_ONCE(rnp->expmask) == 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* Report the exit from RCU read-side critical section for the last task
|
||||
* that queued itself during or before the current expedited preemptible-RCU
|
||||
* grace period. This event is reported either to the rcu_node structure on
|
||||
* which the task was queued or to one of that rcu_node structure's ancestors,
|
||||
* recursively up the tree. (Calm down, calm down, we do the recursion
|
||||
* iteratively!)
|
||||
*
|
||||
* Caller must hold the rcu_state's exp_mutex and the specified rcu_node
|
||||
* structure's ->lock.
|
||||
*/
|
||||
static void __rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
|
||||
bool wake, unsigned long flags)
|
||||
__releases(rnp->lock)
|
||||
{
|
||||
unsigned long mask;
|
||||
|
||||
for (;;) {
|
||||
if (!sync_rcu_preempt_exp_done(rnp)) {
|
||||
if (!rnp->expmask)
|
||||
rcu_initiate_boost(rnp, flags);
|
||||
else
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
break;
|
||||
}
|
||||
if (rnp->parent == NULL) {
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
if (wake) {
|
||||
smp_mb(); /* EGP done before wake_up(). */
|
||||
swake_up(&rsp->expedited_wq);
|
||||
}
|
||||
break;
|
||||
}
|
||||
mask = rnp->grpmask;
|
||||
raw_spin_unlock_rcu_node(rnp); /* irqs remain disabled */
|
||||
rnp = rnp->parent;
|
||||
raw_spin_lock_rcu_node(rnp); /* irqs already disabled */
|
||||
WARN_ON_ONCE(!(rnp->expmask & mask));
|
||||
rnp->expmask &= ~mask;
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Report expedited quiescent state for specified node. This is a
|
||||
* lock-acquisition wrapper function for __rcu_report_exp_rnp().
|
||||
*
|
||||
* Caller must hold the rcu_state's exp_mutex.
|
||||
*/
|
||||
static void __maybe_unused rcu_report_exp_rnp(struct rcu_state *rsp,
|
||||
struct rcu_node *rnp, bool wake)
|
||||
{
|
||||
unsigned long flags;
|
||||
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
__rcu_report_exp_rnp(rsp, rnp, wake, flags);
|
||||
}
|
||||
|
||||
/*
|
||||
* Report expedited quiescent state for multiple CPUs, all covered by the
|
||||
* specified leaf rcu_node structure. Caller must hold the rcu_state's
|
||||
* exp_mutex.
|
||||
*/
|
||||
static void rcu_report_exp_cpu_mult(struct rcu_state *rsp, struct rcu_node *rnp,
|
||||
unsigned long mask, bool wake)
|
||||
{
|
||||
unsigned long flags;
|
||||
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
if (!(rnp->expmask & mask)) {
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
return;
|
||||
}
|
||||
rnp->expmask &= ~mask;
|
||||
__rcu_report_exp_rnp(rsp, rnp, wake, flags); /* Releases rnp->lock. */
|
||||
}
|
||||
|
||||
/*
|
||||
* Report expedited quiescent state for specified rcu_data (CPU).
|
||||
*/
|
||||
static void rcu_report_exp_rdp(struct rcu_state *rsp, struct rcu_data *rdp,
|
||||
bool wake)
|
||||
{
|
||||
rcu_report_exp_cpu_mult(rsp, rdp->mynode, rdp->grpmask, wake);
|
||||
}
|
||||
|
||||
/* Common code for synchronize_{rcu,sched}_expedited() work-done checking. */
|
||||
static bool sync_exp_work_done(struct rcu_state *rsp, atomic_long_t *stat,
|
||||
unsigned long s)
|
||||
{
|
||||
if (rcu_exp_gp_seq_done(rsp, s)) {
|
||||
trace_rcu_exp_grace_period(rsp->name, s, TPS("done"));
|
||||
/* Ensure test happens before caller kfree(). */
|
||||
smp_mb__before_atomic(); /* ^^^ */
|
||||
atomic_long_inc(stat);
|
||||
return true;
|
||||
}
|
||||
return false;
|
||||
}
|
||||
|
||||
/*
|
||||
* Funnel-lock acquisition for expedited grace periods. Returns true
|
||||
* if some other task completed an expedited grace period that this task
|
||||
* can piggy-back on, and with no mutex held. Otherwise, returns false
|
||||
* with the mutex held, indicating that the caller must actually do the
|
||||
* expedited grace period.
|
||||
*/
|
||||
static bool exp_funnel_lock(struct rcu_state *rsp, unsigned long s)
|
||||
{
|
||||
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, raw_smp_processor_id());
|
||||
struct rcu_node *rnp = rdp->mynode;
|
||||
struct rcu_node *rnp_root = rcu_get_root(rsp);
|
||||
|
||||
/* Low-contention fastpath. */
|
||||
if (ULONG_CMP_LT(READ_ONCE(rnp->exp_seq_rq), s) &&
|
||||
(rnp == rnp_root ||
|
||||
ULONG_CMP_LT(READ_ONCE(rnp_root->exp_seq_rq), s)) &&
|
||||
!mutex_is_locked(&rsp->exp_mutex) &&
|
||||
mutex_trylock(&rsp->exp_mutex))
|
||||
goto fastpath;
|
||||
|
||||
/*
|
||||
* Each pass through the following loop works its way up
|
||||
* the rcu_node tree, returning if others have done the work or
|
||||
* otherwise falls through to acquire rsp->exp_mutex. The mapping
|
||||
* from CPU to rcu_node structure can be inexact, as it is just
|
||||
* promoting locality and is not strictly needed for correctness.
|
||||
*/
|
||||
for (; rnp != NULL; rnp = rnp->parent) {
|
||||
if (sync_exp_work_done(rsp, &rdp->exp_workdone1, s))
|
||||
return true;
|
||||
|
||||
/* Work not done, either wait here or go up. */
|
||||
spin_lock(&rnp->exp_lock);
|
||||
if (ULONG_CMP_GE(rnp->exp_seq_rq, s)) {
|
||||
|
||||
/* Someone else doing GP, so wait for them. */
|
||||
spin_unlock(&rnp->exp_lock);
|
||||
trace_rcu_exp_funnel_lock(rsp->name, rnp->level,
|
||||
rnp->grplo, rnp->grphi,
|
||||
TPS("wait"));
|
||||
wait_event(rnp->exp_wq[(s >> 1) & 0x3],
|
||||
sync_exp_work_done(rsp,
|
||||
&rdp->exp_workdone2, s));
|
||||
return true;
|
||||
}
|
||||
rnp->exp_seq_rq = s; /* Followers can wait on us. */
|
||||
spin_unlock(&rnp->exp_lock);
|
||||
trace_rcu_exp_funnel_lock(rsp->name, rnp->level, rnp->grplo,
|
||||
rnp->grphi, TPS("nxtlvl"));
|
||||
}
|
||||
mutex_lock(&rsp->exp_mutex);
|
||||
fastpath:
|
||||
if (sync_exp_work_done(rsp, &rdp->exp_workdone3, s)) {
|
||||
mutex_unlock(&rsp->exp_mutex);
|
||||
return true;
|
||||
}
|
||||
rcu_exp_gp_seq_start(rsp);
|
||||
trace_rcu_exp_grace_period(rsp->name, s, TPS("start"));
|
||||
return false;
|
||||
}
|
||||
|
||||
/* Invoked on each online non-idle CPU for expedited quiescent state. */
|
||||
static void sync_sched_exp_handler(void *data)
|
||||
{
|
||||
struct rcu_data *rdp;
|
||||
struct rcu_node *rnp;
|
||||
struct rcu_state *rsp = data;
|
||||
|
||||
rdp = this_cpu_ptr(rsp->rda);
|
||||
rnp = rdp->mynode;
|
||||
if (!(READ_ONCE(rnp->expmask) & rdp->grpmask) ||
|
||||
__this_cpu_read(rcu_sched_data.cpu_no_qs.b.exp))
|
||||
return;
|
||||
if (rcu_is_cpu_rrupt_from_idle()) {
|
||||
rcu_report_exp_rdp(&rcu_sched_state,
|
||||
this_cpu_ptr(&rcu_sched_data), true);
|
||||
return;
|
||||
}
|
||||
__this_cpu_write(rcu_sched_data.cpu_no_qs.b.exp, true);
|
||||
resched_cpu(smp_processor_id());
|
||||
}
|
||||
|
||||
/* Send IPI for expedited cleanup if needed at end of CPU-hotplug operation. */
|
||||
static void sync_sched_exp_online_cleanup(int cpu)
|
||||
{
|
||||
struct rcu_data *rdp;
|
||||
int ret;
|
||||
struct rcu_node *rnp;
|
||||
struct rcu_state *rsp = &rcu_sched_state;
|
||||
|
||||
rdp = per_cpu_ptr(rsp->rda, cpu);
|
||||
rnp = rdp->mynode;
|
||||
if (!(READ_ONCE(rnp->expmask) & rdp->grpmask))
|
||||
return;
|
||||
ret = smp_call_function_single(cpu, sync_sched_exp_handler, rsp, 0);
|
||||
WARN_ON_ONCE(ret);
|
||||
}
|
||||
|
||||
/*
|
||||
* Select the nodes that the upcoming expedited grace period needs
|
||||
* to wait for.
|
||||
*/
|
||||
static void sync_rcu_exp_select_cpus(struct rcu_state *rsp,
|
||||
smp_call_func_t func)
|
||||
{
|
||||
int cpu;
|
||||
unsigned long flags;
|
||||
unsigned long mask_ofl_test;
|
||||
unsigned long mask_ofl_ipi;
|
||||
int ret;
|
||||
struct rcu_node *rnp;
|
||||
|
||||
sync_exp_reset_tree(rsp);
|
||||
rcu_for_each_leaf_node(rsp, rnp) {
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
|
||||
/* Each pass checks a CPU for identity, offline, and idle. */
|
||||
mask_ofl_test = 0;
|
||||
for_each_leaf_node_possible_cpu(rnp, cpu) {
|
||||
struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
|
||||
struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
|
||||
|
||||
if (raw_smp_processor_id() == cpu ||
|
||||
!(atomic_add_return(0, &rdtp->dynticks) & 0x1))
|
||||
mask_ofl_test |= rdp->grpmask;
|
||||
}
|
||||
mask_ofl_ipi = rnp->expmask & ~mask_ofl_test;
|
||||
|
||||
/*
|
||||
* Need to wait for any blocked tasks as well. Note that
|
||||
* additional blocking tasks will also block the expedited
|
||||
* GP until such time as the ->expmask bits are cleared.
|
||||
*/
|
||||
if (rcu_preempt_has_tasks(rnp))
|
||||
rnp->exp_tasks = rnp->blkd_tasks.next;
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
|
||||
/* IPI the remaining CPUs for expedited quiescent state. */
|
||||
for_each_leaf_node_possible_cpu(rnp, cpu) {
|
||||
unsigned long mask = leaf_node_cpu_bit(rnp, cpu);
|
||||
if (!(mask_ofl_ipi & mask))
|
||||
continue;
|
||||
retry_ipi:
|
||||
ret = smp_call_function_single(cpu, func, rsp, 0);
|
||||
if (!ret) {
|
||||
mask_ofl_ipi &= ~mask;
|
||||
continue;
|
||||
}
|
||||
/* Failed, raced with offline. */
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
if (cpu_online(cpu) &&
|
||||
(rnp->expmask & mask)) {
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
schedule_timeout_uninterruptible(1);
|
||||
if (cpu_online(cpu) &&
|
||||
(rnp->expmask & mask))
|
||||
goto retry_ipi;
|
||||
raw_spin_lock_irqsave_rcu_node(rnp, flags);
|
||||
}
|
||||
if (!(rnp->expmask & mask))
|
||||
mask_ofl_ipi &= ~mask;
|
||||
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
|
||||
}
|
||||
/* Report quiescent states for those that went offline. */
|
||||
mask_ofl_test |= mask_ofl_ipi;
|
||||
if (mask_ofl_test)
|
||||
rcu_report_exp_cpu_mult(rsp, rnp, mask_ofl_test, false);
|
||||
}
|
||||
}
|
||||
|
||||
static void synchronize_sched_expedited_wait(struct rcu_state *rsp)
|
||||
{
|
||||
int cpu;
|
||||
unsigned long jiffies_stall;
|
||||
unsigned long jiffies_start;
|
||||
unsigned long mask;
|
||||
int ndetected;
|
||||
struct rcu_node *rnp;
|
||||
struct rcu_node *rnp_root = rcu_get_root(rsp);
|
||||
int ret;
|
||||
|
||||
jiffies_stall = rcu_jiffies_till_stall_check();
|
||||
jiffies_start = jiffies;
|
||||
|
||||
for (;;) {
|
||||
ret = swait_event_timeout(
|
||||
rsp->expedited_wq,
|
||||
sync_rcu_preempt_exp_done(rnp_root),
|
||||
jiffies_stall);
|
||||
if (ret > 0 || sync_rcu_preempt_exp_done(rnp_root))
|
||||
return;
|
||||
if (ret < 0) {
|
||||
/* Hit a signal, disable CPU stall warnings. */
|
||||
swait_event(rsp->expedited_wq,
|
||||
sync_rcu_preempt_exp_done(rnp_root));
|
||||
return;
|
||||
}
|
||||
pr_err("INFO: %s detected expedited stalls on CPUs/tasks: {",
|
||||
rsp->name);
|
||||
ndetected = 0;
|
||||
rcu_for_each_leaf_node(rsp, rnp) {
|
||||
ndetected += rcu_print_task_exp_stall(rnp);
|
||||
for_each_leaf_node_possible_cpu(rnp, cpu) {
|
||||
struct rcu_data *rdp;
|
||||
|
||||
mask = leaf_node_cpu_bit(rnp, cpu);
|
||||
if (!(rnp->expmask & mask))
|
||||
continue;
|
||||
ndetected++;
|
||||
rdp = per_cpu_ptr(rsp->rda, cpu);
|
||||
pr_cont(" %d-%c%c%c", cpu,
|
||||
"O."[!!cpu_online(cpu)],
|
||||
"o."[!!(rdp->grpmask & rnp->expmaskinit)],
|
||||
"N."[!!(rdp->grpmask & rnp->expmaskinitnext)]);
|
||||
}
|
||||
}
|
||||
pr_cont(" } %lu jiffies s: %lu root: %#lx/%c\n",
|
||||
jiffies - jiffies_start, rsp->expedited_sequence,
|
||||
rnp_root->expmask, ".T"[!!rnp_root->exp_tasks]);
|
||||
if (ndetected) {
|
||||
pr_err("blocking rcu_node structures:");
|
||||
rcu_for_each_node_breadth_first(rsp, rnp) {
|
||||
if (rnp == rnp_root)
|
||||
continue; /* printed unconditionally */
|
||||
if (sync_rcu_preempt_exp_done(rnp))
|
||||
continue;
|
||||
pr_cont(" l=%u:%d-%d:%#lx/%c",
|
||||
rnp->level, rnp->grplo, rnp->grphi,
|
||||
rnp->expmask,
|
||||
".T"[!!rnp->exp_tasks]);
|
||||
}
|
||||
pr_cont("\n");
|
||||
}
|
||||
rcu_for_each_leaf_node(rsp, rnp) {
|
||||
for_each_leaf_node_possible_cpu(rnp, cpu) {
|
||||
mask = leaf_node_cpu_bit(rnp, cpu);
|
||||
if (!(rnp->expmask & mask))
|
||||
continue;
|
||||
dump_cpu_task(cpu);
|
||||
}
|
||||
}
|
||||
jiffies_stall = 3 * rcu_jiffies_till_stall_check() + 3;
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Wait for the current expedited grace period to complete, and then
|
||||
* wake up everyone who piggybacked on the just-completed expedited
|
||||
* grace period. Also update all the ->exp_seq_rq counters as needed
|
||||
* in order to avoid counter-wrap problems.
|
||||
*/
|
||||
static void rcu_exp_wait_wake(struct rcu_state *rsp, unsigned long s)
|
||||
{
|
||||
struct rcu_node *rnp;
|
||||
|
||||
synchronize_sched_expedited_wait(rsp);
|
||||
rcu_exp_gp_seq_end(rsp);
|
||||
trace_rcu_exp_grace_period(rsp->name, s, TPS("end"));
|
||||
|
||||
/*
|
||||
* Switch over to wakeup mode, allowing the next GP, but -only- the
|
||||
* next GP, to proceed.
|
||||
*/
|
||||
mutex_lock(&rsp->exp_wake_mutex);
|
||||
mutex_unlock(&rsp->exp_mutex);
|
||||
|
||||
rcu_for_each_node_breadth_first(rsp, rnp) {
|
||||
if (ULONG_CMP_LT(READ_ONCE(rnp->exp_seq_rq), s)) {
|
||||
spin_lock(&rnp->exp_lock);
|
||||
/* Recheck, avoid hang in case someone just arrived. */
|
||||
if (ULONG_CMP_LT(rnp->exp_seq_rq, s))
|
||||
rnp->exp_seq_rq = s;
|
||||
spin_unlock(&rnp->exp_lock);
|
||||
}
|
||||
wake_up_all(&rnp->exp_wq[(rsp->expedited_sequence >> 1) & 0x3]);
|
||||
}
|
||||
trace_rcu_exp_grace_period(rsp->name, s, TPS("endwake"));
|
||||
mutex_unlock(&rsp->exp_wake_mutex);
|
||||
}
|
||||
|
||||
/**
|
||||
* synchronize_sched_expedited - Brute-force RCU-sched grace period
|
||||
*
|
||||
* Wait for an RCU-sched grace period to elapse, but use a "big hammer"
|
||||
* approach to force the grace period to end quickly. This consumes
|
||||
* significant time on all CPUs and is unfriendly to real-time workloads,
|
||||
* so is thus not recommended for any sort of common-case code. In fact,
|
||||
* if you are using synchronize_sched_expedited() in a loop, please
|
||||
* restructure your code to batch your updates, and then use a single
|
||||
* synchronize_sched() instead.
|
||||
*
|
||||
* This implementation can be thought of as an application of sequence
|
||||
* locking to expedited grace periods, but using the sequence counter to
|
||||
* determine when someone else has already done the work instead of for
|
||||
* retrying readers.
|
||||
*/
|
||||
void synchronize_sched_expedited(void)
|
||||
{
|
||||
unsigned long s;
|
||||
struct rcu_state *rsp = &rcu_sched_state;
|
||||
|
||||
/* If only one CPU, this is automatically a grace period. */
|
||||
if (rcu_blocking_is_gp())
|
||||
return;
|
||||
|
||||
/* If expedited grace periods are prohibited, fall back to normal. */
|
||||
if (rcu_gp_is_normal()) {
|
||||
wait_rcu_gp(call_rcu_sched);
|
||||
return;
|
||||
}
|
||||
|
||||
/* Take a snapshot of the sequence number. */
|
||||
s = rcu_exp_gp_seq_snap(rsp);
|
||||
if (exp_funnel_lock(rsp, s))
|
||||
return; /* Someone else did our work for us. */
|
||||
|
||||
/* Initialize the rcu_node tree in preparation for the wait. */
|
||||
sync_rcu_exp_select_cpus(rsp, sync_sched_exp_handler);
|
||||
|
||||
/* Wait and clean up, including waking everyone. */
|
||||
rcu_exp_wait_wake(rsp, s);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
|
||||
|
||||
#ifdef CONFIG_PREEMPT_RCU
|
||||
|
||||
/*
|
||||
* Remote handler for smp_call_function_single(). If there is an
|
||||
* RCU read-side critical section in effect, request that the
|
||||
* next rcu_read_unlock() record the quiescent state up the
|
||||
* ->expmask fields in the rcu_node tree. Otherwise, immediately
|
||||
* report the quiescent state.
|
||||
*/
|
||||
static void sync_rcu_exp_handler(void *info)
|
||||
{
|
||||
struct rcu_data *rdp;
|
||||
struct rcu_state *rsp = info;
|
||||
struct task_struct *t = current;
|
||||
|
||||
/*
|
||||
* Within an RCU read-side critical section, request that the next
|
||||
* rcu_read_unlock() report. Unless this RCU read-side critical
|
||||
* section has already blocked, in which case it is already set
|
||||
* up for the expedited grace period to wait on it.
|
||||
*/
|
||||
if (t->rcu_read_lock_nesting > 0 &&
|
||||
!t->rcu_read_unlock_special.b.blocked) {
|
||||
t->rcu_read_unlock_special.b.exp_need_qs = true;
|
||||
return;
|
||||
}
|
||||
|
||||
/*
|
||||
* We are either exiting an RCU read-side critical section (negative
|
||||
* values of t->rcu_read_lock_nesting) or are not in one at all
|
||||
* (zero value of t->rcu_read_lock_nesting). Or we are in an RCU
|
||||
* read-side critical section that blocked before this expedited
|
||||
* grace period started. Either way, we can immediately report
|
||||
* the quiescent state.
|
||||
*/
|
||||
rdp = this_cpu_ptr(rsp->rda);
|
||||
rcu_report_exp_rdp(rsp, rdp, true);
|
||||
}
|
||||
|
||||
/**
|
||||
* synchronize_rcu_expedited - Brute-force RCU grace period
|
||||
*
|
||||
* Wait for an RCU-preempt grace period, but expedite it. The basic
|
||||
* idea is to IPI all non-idle non-nohz online CPUs. The IPI handler
|
||||
* checks whether the CPU is in an RCU-preempt critical section, and
|
||||
* if so, it sets a flag that causes the outermost rcu_read_unlock()
|
||||
* to report the quiescent state. On the other hand, if the CPU is
|
||||
* not in an RCU read-side critical section, the IPI handler reports
|
||||
* the quiescent state immediately.
|
||||
*
|
||||
* Although this is a greate improvement over previous expedited
|
||||
* implementations, it is still unfriendly to real-time workloads, so is
|
||||
* thus not recommended for any sort of common-case code. In fact, if
|
||||
* you are using synchronize_rcu_expedited() in a loop, please restructure
|
||||
* your code to batch your updates, and then Use a single synchronize_rcu()
|
||||
* instead.
|
||||
*/
|
||||
void synchronize_rcu_expedited(void)
|
||||
{
|
||||
struct rcu_state *rsp = rcu_state_p;
|
||||
unsigned long s;
|
||||
|
||||
/* If expedited grace periods are prohibited, fall back to normal. */
|
||||
if (rcu_gp_is_normal()) {
|
||||
wait_rcu_gp(call_rcu);
|
||||
return;
|
||||
}
|
||||
|
||||
s = rcu_exp_gp_seq_snap(rsp);
|
||||
if (exp_funnel_lock(rsp, s))
|
||||
return; /* Someone else did our work for us. */
|
||||
|
||||
/* Initialize the rcu_node tree in preparation for the wait. */
|
||||
sync_rcu_exp_select_cpus(rsp, sync_rcu_exp_handler);
|
||||
|
||||
/* Wait for ->blkd_tasks lists to drain, then wake everyone up. */
|
||||
rcu_exp_wait_wake(rsp, s);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);
|
||||
|
||||
#else /* #ifdef CONFIG_PREEMPT_RCU */
|
||||
|
||||
/*
|
||||
* Wait for an rcu-preempt grace period, but make it happen quickly.
|
||||
* But because preemptible RCU does not exist, map to rcu-sched.
|
||||
*/
|
||||
void synchronize_rcu_expedited(void)
|
||||
{
|
||||
synchronize_sched_expedited();
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);
|
||||
|
||||
#endif /* #else #ifdef CONFIG_PREEMPT_RCU */
|
|
@ -79,8 +79,6 @@ static void __init rcu_bootup_announce_oddness(void)
|
|||
pr_info("\tRCU dyntick-idle grace-period acceleration is enabled.\n");
|
||||
if (IS_ENABLED(CONFIG_PROVE_RCU))
|
||||
pr_info("\tRCU lockdep checking is enabled.\n");
|
||||
if (IS_ENABLED(CONFIG_RCU_TORTURE_TEST_RUNNABLE))
|
||||
pr_info("\tRCU torture testing starts during boot.\n");
|
||||
if (RCU_NUM_LVLS >= 4)
|
||||
pr_info("\tFour(or more)-level hierarchy is enabled.\n");
|
||||
if (RCU_FANOUT_LEAF != 16)
|
||||
|
@ -681,84 +679,6 @@ void synchronize_rcu(void)
|
|||
}
|
||||
EXPORT_SYMBOL_GPL(synchronize_rcu);
|
||||
|
||||
/*
|
||||
* Remote handler for smp_call_function_single(). If there is an
|
||||
* RCU read-side critical section in effect, request that the
|
||||
* next rcu_read_unlock() record the quiescent state up the
|
||||
* ->expmask fields in the rcu_node tree. Otherwise, immediately
|
||||
* report the quiescent state.
|
||||
*/
|
||||
static void sync_rcu_exp_handler(void *info)
|
||||
{
|
||||
struct rcu_data *rdp;
|
||||
struct rcu_state *rsp = info;
|
||||
struct task_struct *t = current;
|
||||
|
||||
/*
|
||||
* Within an RCU read-side critical section, request that the next
|
||||
* rcu_read_unlock() report. Unless this RCU read-side critical
|
||||
* section has already blocked, in which case it is already set
|
||||
* up for the expedited grace period to wait on it.
|
||||
*/
|
||||
if (t->rcu_read_lock_nesting > 0 &&
|
||||
!t->rcu_read_unlock_special.b.blocked) {
|
||||
t->rcu_read_unlock_special.b.exp_need_qs = true;
|
||||
return;
|
||||
}
|
||||
|
||||
/*
|
||||
* We are either exiting an RCU read-side critical section (negative
|
||||
* values of t->rcu_read_lock_nesting) or are not in one at all
|
||||
* (zero value of t->rcu_read_lock_nesting). Or we are in an RCU
|
||||
* read-side critical section that blocked before this expedited
|
||||
* grace period started. Either way, we can immediately report
|
||||
* the quiescent state.
|
||||
*/
|
||||
rdp = this_cpu_ptr(rsp->rda);
|
||||
rcu_report_exp_rdp(rsp, rdp, true);
|
||||
}
|
||||
|
||||
/**
|
||||
* synchronize_rcu_expedited - Brute-force RCU grace period
|
||||
*
|
||||
* Wait for an RCU-preempt grace period, but expedite it. The basic
|
||||
* idea is to IPI all non-idle non-nohz online CPUs. The IPI handler
|
||||
* checks whether the CPU is in an RCU-preempt critical section, and
|
||||
* if so, it sets a flag that causes the outermost rcu_read_unlock()
|
||||
* to report the quiescent state. On the other hand, if the CPU is
|
||||
* not in an RCU read-side critical section, the IPI handler reports
|
||||
* the quiescent state immediately.
|
||||
*
|
||||
* Although this is a greate improvement over previous expedited
|
||||
* implementations, it is still unfriendly to real-time workloads, so is
|
||||
* thus not recommended for any sort of common-case code. In fact, if
|
||||
* you are using synchronize_rcu_expedited() in a loop, please restructure
|
||||
* your code to batch your updates, and then Use a single synchronize_rcu()
|
||||
* instead.
|
||||
*/
|
||||
void synchronize_rcu_expedited(void)
|
||||
{
|
||||
struct rcu_state *rsp = rcu_state_p;
|
||||
unsigned long s;
|
||||
|
||||
/* If expedited grace periods are prohibited, fall back to normal. */
|
||||
if (rcu_gp_is_normal()) {
|
||||
wait_rcu_gp(call_rcu);
|
||||
return;
|
||||
}
|
||||
|
||||
s = rcu_exp_gp_seq_snap(rsp);
|
||||
if (exp_funnel_lock(rsp, s))
|
||||
return; /* Someone else did our work for us. */
|
||||
|
||||
/* Initialize the rcu_node tree in preparation for the wait. */
|
||||
sync_rcu_exp_select_cpus(rsp, sync_rcu_exp_handler);
|
||||
|
||||
/* Wait for ->blkd_tasks lists to drain, then wake everyone up. */
|
||||
rcu_exp_wait_wake(rsp, s);
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);
|
||||
|
||||
/**
|
||||
* rcu_barrier - Wait until all in-flight call_rcu() callbacks complete.
|
||||
*
|
||||
|
@ -882,16 +802,6 @@ static void rcu_preempt_check_callbacks(void)
|
|||
{
|
||||
}
|
||||
|
||||
/*
|
||||
* Wait for an rcu-preempt grace period, but make it happen quickly.
|
||||
* But because preemptible RCU does not exist, map to rcu-sched.
|
||||
*/
|
||||
void synchronize_rcu_expedited(void)
|
||||
{
|
||||
synchronize_sched_expedited();
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);
|
||||
|
||||
/*
|
||||
* Because preemptible RCU does not exist, rcu_barrier() is just
|
||||
* another name for rcu_barrier_sched().
|
||||
|
@ -1254,8 +1164,9 @@ static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
|
|||
return;
|
||||
if (!zalloc_cpumask_var(&cm, GFP_KERNEL))
|
||||
return;
|
||||
for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1)
|
||||
if ((mask & 0x1) && cpu != outgoingcpu)
|
||||
for_each_leaf_node_possible_cpu(rnp, cpu)
|
||||
if ((mask & leaf_node_cpu_bit(rnp, cpu)) &&
|
||||
cpu != outgoingcpu)
|
||||
cpumask_set_cpu(cpu, cm);
|
||||
if (cpumask_weight(cm) == 0)
|
||||
cpumask_setall(cm);
|
||||
|
|
|
@ -528,6 +528,7 @@ static int rcu_task_stall_timeout __read_mostly = HZ * 60 * 10;
|
|||
module_param(rcu_task_stall_timeout, int, 0644);
|
||||
|
||||
static void rcu_spawn_tasks_kthread(void);
|
||||
static struct task_struct *rcu_tasks_kthread_ptr;
|
||||
|
||||
/*
|
||||
* Post an RCU-tasks callback. First call must be from process context
|
||||
|
@ -537,6 +538,7 @@ void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func)
|
|||
{
|
||||
unsigned long flags;
|
||||
bool needwake;
|
||||
bool havetask = READ_ONCE(rcu_tasks_kthread_ptr);
|
||||
|
||||
rhp->next = NULL;
|
||||
rhp->func = func;
|
||||
|
@ -545,7 +547,9 @@ void call_rcu_tasks(struct rcu_head *rhp, rcu_callback_t func)
|
|||
*rcu_tasks_cbs_tail = rhp;
|
||||
rcu_tasks_cbs_tail = &rhp->next;
|
||||
raw_spin_unlock_irqrestore(&rcu_tasks_cbs_lock, flags);
|
||||
if (needwake) {
|
||||
/* We can't create the thread unless interrupts are enabled. */
|
||||
if ((needwake && havetask) ||
|
||||
(!havetask && !irqs_disabled_flags(flags))) {
|
||||
rcu_spawn_tasks_kthread();
|
||||
wake_up(&rcu_tasks_cbs_wq);
|
||||
}
|
||||
|
@ -790,7 +794,6 @@ static int __noreturn rcu_tasks_kthread(void *arg)
|
|||
static void rcu_spawn_tasks_kthread(void)
|
||||
{
|
||||
static DEFINE_MUTEX(rcu_tasks_kthread_mutex);
|
||||
static struct task_struct *rcu_tasks_kthread_ptr;
|
||||
struct task_struct *t;
|
||||
|
||||
if (READ_ONCE(rcu_tasks_kthread_ptr)) {
|
||||
|
|
|
@ -1204,6 +1204,17 @@ static struct ctl_table kern_table[] = {
|
|||
.extra1 = &one,
|
||||
.extra2 = &one,
|
||||
},
|
||||
#endif
|
||||
#if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU)
|
||||
{
|
||||
.procname = "panic_on_rcu_stall",
|
||||
.data = &sysctl_panic_on_rcu_stall,
|
||||
.maxlen = sizeof(sysctl_panic_on_rcu_stall),
|
||||
.mode = 0644,
|
||||
.proc_handler = proc_dointvec_minmax,
|
||||
.extra1 = &zero,
|
||||
.extra2 = &one,
|
||||
},
|
||||
#endif
|
||||
{ }
|
||||
};
|
||||
|
|
176
kernel/torture.c
176
kernel/torture.c
|
@ -81,6 +81,104 @@ static unsigned long sum_online;
|
|||
static int min_online = -1;
|
||||
static int max_online;
|
||||
|
||||
/*
|
||||
* Attempt to take a CPU offline. Return false if the CPU is already
|
||||
* offline or if it is not subject to CPU-hotplug operations. The
|
||||
* caller can detect other failures by looking at the statistics.
|
||||
*/
|
||||
bool torture_offline(int cpu, long *n_offl_attempts, long *n_offl_successes,
|
||||
unsigned long *sum_offl, int *min_offl, int *max_offl)
|
||||
{
|
||||
unsigned long delta;
|
||||
int ret;
|
||||
unsigned long starttime;
|
||||
|
||||
if (!cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
|
||||
return false;
|
||||
|
||||
if (verbose)
|
||||
pr_alert("%s" TORTURE_FLAG
|
||||
"torture_onoff task: offlining %d\n",
|
||||
torture_type, cpu);
|
||||
starttime = jiffies;
|
||||
(*n_offl_attempts)++;
|
||||
ret = cpu_down(cpu);
|
||||
if (ret) {
|
||||
if (verbose)
|
||||
pr_alert("%s" TORTURE_FLAG
|
||||
"torture_onoff task: offline %d failed: errno %d\n",
|
||||
torture_type, cpu, ret);
|
||||
} else {
|
||||
if (verbose)
|
||||
pr_alert("%s" TORTURE_FLAG
|
||||
"torture_onoff task: offlined %d\n",
|
||||
torture_type, cpu);
|
||||
(*n_offl_successes)++;
|
||||
delta = jiffies - starttime;
|
||||
sum_offl += delta;
|
||||
if (*min_offl < 0) {
|
||||
*min_offl = delta;
|
||||
*max_offl = delta;
|
||||
}
|
||||
if (*min_offl > delta)
|
||||
*min_offl = delta;
|
||||
if (*max_offl < delta)
|
||||
*max_offl = delta;
|
||||
}
|
||||
|
||||
return true;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(torture_offline);
|
||||
|
||||
/*
|
||||
* Attempt to bring a CPU online. Return false if the CPU is already
|
||||
* online or if it is not subject to CPU-hotplug operations. The
|
||||
* caller can detect other failures by looking at the statistics.
|
||||
*/
|
||||
bool torture_online(int cpu, long *n_onl_attempts, long *n_onl_successes,
|
||||
unsigned long *sum_onl, int *min_onl, int *max_onl)
|
||||
{
|
||||
unsigned long delta;
|
||||
int ret;
|
||||
unsigned long starttime;
|
||||
|
||||
if (cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
|
||||
return false;
|
||||
|
||||
if (verbose)
|
||||
pr_alert("%s" TORTURE_FLAG
|
||||
"torture_onoff task: onlining %d\n",
|
||||
torture_type, cpu);
|
||||
starttime = jiffies;
|
||||
(*n_onl_attempts)++;
|
||||
ret = cpu_up(cpu);
|
||||
if (ret) {
|
||||
if (verbose)
|
||||
pr_alert("%s" TORTURE_FLAG
|
||||
"torture_onoff task: online %d failed: errno %d\n",
|
||||
torture_type, cpu, ret);
|
||||
} else {
|
||||
if (verbose)
|
||||
pr_alert("%s" TORTURE_FLAG
|
||||
"torture_onoff task: onlined %d\n",
|
||||
torture_type, cpu);
|
||||
(*n_onl_successes)++;
|
||||
delta = jiffies - starttime;
|
||||
*sum_onl += delta;
|
||||
if (*min_onl < 0) {
|
||||
*min_onl = delta;
|
||||
*max_onl = delta;
|
||||
}
|
||||
if (*min_onl > delta)
|
||||
*min_onl = delta;
|
||||
if (*max_onl < delta)
|
||||
*max_onl = delta;
|
||||
}
|
||||
|
||||
return true;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(torture_online);
|
||||
|
||||
/*
|
||||
* Execute random CPU-hotplug operations at the interval specified
|
||||
* by the onoff_interval.
|
||||
|
@ -89,16 +187,19 @@ static int
|
|||
torture_onoff(void *arg)
|
||||
{
|
||||
int cpu;
|
||||
unsigned long delta;
|
||||
int maxcpu = -1;
|
||||
DEFINE_TORTURE_RANDOM(rand);
|
||||
int ret;
|
||||
unsigned long starttime;
|
||||
|
||||
VERBOSE_TOROUT_STRING("torture_onoff task started");
|
||||
for_each_online_cpu(cpu)
|
||||
maxcpu = cpu;
|
||||
WARN_ON(maxcpu < 0);
|
||||
|
||||
if (maxcpu == 0) {
|
||||
VERBOSE_TOROUT_STRING("Only one CPU, so CPU-hotplug testing is disabled");
|
||||
goto stop;
|
||||
}
|
||||
|
||||
if (onoff_holdoff > 0) {
|
||||
VERBOSE_TOROUT_STRING("torture_onoff begin holdoff");
|
||||
schedule_timeout_interruptible(onoff_holdoff);
|
||||
|
@ -106,69 +207,16 @@ torture_onoff(void *arg)
|
|||
}
|
||||
while (!torture_must_stop()) {
|
||||
cpu = (torture_random(&rand) >> 4) % (maxcpu + 1);
|
||||
if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
|
||||
if (verbose)
|
||||
pr_alert("%s" TORTURE_FLAG
|
||||
"torture_onoff task: offlining %d\n",
|
||||
torture_type, cpu);
|
||||
starttime = jiffies;
|
||||
n_offline_attempts++;
|
||||
ret = cpu_down(cpu);
|
||||
if (ret) {
|
||||
if (verbose)
|
||||
pr_alert("%s" TORTURE_FLAG
|
||||
"torture_onoff task: offline %d failed: errno %d\n",
|
||||
torture_type, cpu, ret);
|
||||
} else {
|
||||
if (verbose)
|
||||
pr_alert("%s" TORTURE_FLAG
|
||||
"torture_onoff task: offlined %d\n",
|
||||
torture_type, cpu);
|
||||
n_offline_successes++;
|
||||
delta = jiffies - starttime;
|
||||
sum_offline += delta;
|
||||
if (min_offline < 0) {
|
||||
min_offline = delta;
|
||||
max_offline = delta;
|
||||
}
|
||||
if (min_offline > delta)
|
||||
min_offline = delta;
|
||||
if (max_offline < delta)
|
||||
max_offline = delta;
|
||||
}
|
||||
} else if (cpu_is_hotpluggable(cpu)) {
|
||||
if (verbose)
|
||||
pr_alert("%s" TORTURE_FLAG
|
||||
"torture_onoff task: onlining %d\n",
|
||||
torture_type, cpu);
|
||||
starttime = jiffies;
|
||||
n_online_attempts++;
|
||||
ret = cpu_up(cpu);
|
||||
if (ret) {
|
||||
if (verbose)
|
||||
pr_alert("%s" TORTURE_FLAG
|
||||
"torture_onoff task: online %d failed: errno %d\n",
|
||||
torture_type, cpu, ret);
|
||||
} else {
|
||||
if (verbose)
|
||||
pr_alert("%s" TORTURE_FLAG
|
||||
"torture_onoff task: onlined %d\n",
|
||||
torture_type, cpu);
|
||||
n_online_successes++;
|
||||
delta = jiffies - starttime;
|
||||
sum_online += delta;
|
||||
if (min_online < 0) {
|
||||
min_online = delta;
|
||||
max_online = delta;
|
||||
}
|
||||
if (min_online > delta)
|
||||
min_online = delta;
|
||||
if (max_online < delta)
|
||||
max_online = delta;
|
||||
}
|
||||
}
|
||||
if (!torture_offline(cpu,
|
||||
&n_offline_attempts, &n_offline_successes,
|
||||
&sum_offline, &min_offline, &max_offline))
|
||||
torture_online(cpu,
|
||||
&n_online_attempts, &n_online_successes,
|
||||
&sum_online, &min_online, &max_online);
|
||||
schedule_timeout_interruptible(onoff_interval);
|
||||
}
|
||||
|
||||
stop:
|
||||
torture_kthread_stopping("torture_onoff");
|
||||
return 0;
|
||||
}
|
||||
|
|
|
@ -1307,22 +1307,6 @@ config RCU_PERF_TEST
|
|||
Say M if you want the RCU performance tests to build as a module.
|
||||
Say N if you are unsure.
|
||||
|
||||
config RCU_PERF_TEST_RUNNABLE
|
||||
bool "performance tests for RCU runnable by default"
|
||||
depends on RCU_PERF_TEST = y
|
||||
default n
|
||||
help
|
||||
This option provides a way to build the RCU performance tests
|
||||
directly into the kernel without them starting up at boot time.
|
||||
You can use /sys/module to manually override this setting.
|
||||
This /proc file is available only when the RCU performance
|
||||
tests have been built into the kernel.
|
||||
|
||||
Say Y here if you want the RCU performance tests to start during
|
||||
boot (you probably don't).
|
||||
Say N here if you want the RCU performance tests to start only
|
||||
after being manually enabled via /sys/module.
|
||||
|
||||
config RCU_TORTURE_TEST
|
||||
tristate "torture tests for RCU"
|
||||
depends on DEBUG_KERNEL
|
||||
|
@ -1340,23 +1324,6 @@ config RCU_TORTURE_TEST
|
|||
Say M if you want the RCU torture tests to build as a module.
|
||||
Say N if you are unsure.
|
||||
|
||||
config RCU_TORTURE_TEST_RUNNABLE
|
||||
bool "torture tests for RCU runnable by default"
|
||||
depends on RCU_TORTURE_TEST = y
|
||||
default n
|
||||
help
|
||||
This option provides a way to build the RCU torture tests
|
||||
directly into the kernel without them starting up at boot
|
||||
time. You can use /proc/sys/kernel/rcutorture_runnable
|
||||
to manually override this setting. This /proc file is
|
||||
available only when the RCU torture tests have been built
|
||||
into the kernel.
|
||||
|
||||
Say Y here if you want the RCU torture tests to start during
|
||||
boot (you probably don't).
|
||||
Say N here if you want the RCU torture tests to start only
|
||||
after being manually enabled via /proc.
|
||||
|
||||
config RCU_TORTURE_TEST_SLOW_PREINIT
|
||||
bool "Slow down RCU grace-period pre-initialization to expose races"
|
||||
depends on RCU_TORTURE_TEST
|
||||
|
|
|
@ -99,8 +99,9 @@ configfrag_hotplug_cpu () {
|
|||
# identify_boot_image qemu-cmd
|
||||
#
|
||||
# Returns the relative path to the kernel build image. This will be
|
||||
# arch/<arch>/boot/bzImage unless overridden with the TORTURE_BOOT_IMAGE
|
||||
# environment variable.
|
||||
# arch/<arch>/boot/bzImage or vmlinux if bzImage is not a target for the
|
||||
# architecture, unless overridden with the TORTURE_BOOT_IMAGE environment
|
||||
# variable.
|
||||
identify_boot_image () {
|
||||
if test -n "$TORTURE_BOOT_IMAGE"
|
||||
then
|
||||
|
@ -110,11 +111,8 @@ identify_boot_image () {
|
|||
qemu-system-x86_64|qemu-system-i386)
|
||||
echo arch/x86/boot/bzImage
|
||||
;;
|
||||
qemu-system-ppc64)
|
||||
echo arch/powerpc/boot/bzImage
|
||||
;;
|
||||
*)
|
||||
echo ""
|
||||
echo vmlinux
|
||||
;;
|
||||
esac
|
||||
fi
|
||||
|
@ -175,7 +173,7 @@ identify_qemu_args () {
|
|||
qemu-system-x86_64|qemu-system-i386)
|
||||
;;
|
||||
qemu-system-ppc64)
|
||||
echo -enable-kvm -M pseries -cpu POWER7 -nodefaults
|
||||
echo -enable-kvm -M pseries -nodefaults
|
||||
echo -device spapr-vscsi
|
||||
if test -n "$TORTURE_QEMU_INTERACTIVE" -a -n "$TORTURE_QEMU_MAC"
|
||||
then
|
||||
|
|
|
@ -8,9 +8,9 @@
|
|||
#
|
||||
# Usage: kvm-test-1-run.sh config builddir resdir seconds qemu-args boot_args
|
||||
#
|
||||
# qemu-args defaults to "-enable-kvm -soundhw pcspk -nographic", along with
|
||||
# arguments specifying the number of CPUs and other
|
||||
# options generated from the underlying CPU architecture.
|
||||
# qemu-args defaults to "-enable-kvm -nographic", along with arguments
|
||||
# specifying the number of CPUs and other options
|
||||
# generated from the underlying CPU architecture.
|
||||
# boot_args defaults to value returned by the per_version_boot_params
|
||||
# shell function.
|
||||
#
|
||||
|
@ -96,7 +96,8 @@ if test "$base_resdir" != "$resdir" -a -f $base_resdir/bzImage -a -f $base_resdi
|
|||
then
|
||||
# Rerunning previous test, so use that test's kernel.
|
||||
QEMU="`identify_qemu $base_resdir/vmlinux`"
|
||||
KERNEL=$base_resdir/bzImage
|
||||
BOOT_IMAGE="`identify_boot_image $QEMU`"
|
||||
KERNEL=$base_resdir/${BOOT_IMAGE##*/} # use the last component of ${BOOT_IMAGE}
|
||||
ln -s $base_resdir/Make*.out $resdir # for kvm-recheck.sh
|
||||
ln -s $base_resdir/.config $resdir # for kvm-recheck.sh
|
||||
elif kvm-build.sh $config_template $builddir $T
|
||||
|
@ -110,7 +111,7 @@ then
|
|||
if test -n "$BOOT_IMAGE"
|
||||
then
|
||||
cp $builddir/$BOOT_IMAGE $resdir
|
||||
KERNEL=$resdir/bzImage
|
||||
KERNEL=$resdir/${BOOT_IMAGE##*/}
|
||||
else
|
||||
echo No identifiable boot image, not running KVM, see $resdir.
|
||||
echo Do the torture scripts know about your architecture?
|
||||
|
@ -147,7 +148,7 @@ then
|
|||
fi
|
||||
|
||||
# Generate -smp qemu argument.
|
||||
qemu_args="-enable-kvm -soundhw pcspk -nographic $qemu_args"
|
||||
qemu_args="-enable-kvm -nographic $qemu_args"
|
||||
cpu_count=`configNR_CPUS.sh $config_template`
|
||||
cpu_count=`configfrag_boot_cpus "$boot_args" "$config_template" "$cpu_count"`
|
||||
vcpus=`identify_qemu_vcpus`
|
||||
|
@ -229,6 +230,7 @@ fi
|
|||
if test $commandcompleted -eq 0 -a -n "$qemu_pid"
|
||||
then
|
||||
echo Grace period for qemu job at pid $qemu_pid
|
||||
oldline="`tail $resdir/console.log`"
|
||||
while :
|
||||
do
|
||||
kruntime=`awk 'BEGIN { print systime() - '"$kstarttime"' }' < /dev/null`
|
||||
|
@ -238,13 +240,29 @@ then
|
|||
else
|
||||
break
|
||||
fi
|
||||
if test $kruntime -ge $((seconds + $TORTURE_SHUTDOWN_GRACE))
|
||||
must_continue=no
|
||||
newline="`tail $resdir/console.log`"
|
||||
if test "$newline" != "$oldline" && echo $newline | grep -q ' [0-9]\+us : '
|
||||
then
|
||||
must_continue=yes
|
||||
fi
|
||||
last_ts="`tail $resdir/console.log | grep '^\[ *[0-9]\+\.[0-9]\+]' | tail -1 | sed -e 's/^\[ *//' -e 's/\..*$//'`"
|
||||
if test -z "last_ts"
|
||||
then
|
||||
last_ts=0
|
||||
fi
|
||||
if test "$newline" != "$oldline" -a "$last_ts" -lt $((seconds + $TORTURE_SHUTDOWN_GRACE))
|
||||
then
|
||||
must_continue=yes
|
||||
fi
|
||||
if test $must_continue = no -a $kruntime -ge $((seconds + $TORTURE_SHUTDOWN_GRACE))
|
||||
then
|
||||
echo "!!! PID $qemu_pid hung at $kruntime vs. $seconds seconds" >> $resdir/Warnings 2>&1
|
||||
kill -KILL $qemu_pid
|
||||
break
|
||||
fi
|
||||
sleep 1
|
||||
oldline=$newline
|
||||
sleep 10
|
||||
done
|
||||
elif test -z "$qemu_pid"
|
||||
then
|
||||
|
|
|
@ -48,7 +48,7 @@ resdir=""
|
|||
configs=""
|
||||
cpus=0
|
||||
ds=`date +%Y.%m.%d-%H:%M:%S`
|
||||
jitter=0
|
||||
jitter="-1"
|
||||
|
||||
. functions.sh
|
||||
|
||||
|
|
|
@ -33,7 +33,7 @@ if grep -Pq '\x00' < $file
|
|||
then
|
||||
print_warning Console output contains nul bytes, old qemu still running?
|
||||
fi
|
||||
egrep 'Badness|WARNING:|Warn|BUG|===========|Call Trace:|Oops:|detected stalls on CPUs/tasks:|self-detected stall on CPU|Stall ended before state dump start|\?\?\? Writer stall state' < $file | grep -v 'ODEBUG: ' | grep -v 'Warning: unable to open an initial console' > $1.diags
|
||||
egrep 'Badness|WARNING:|Warn|BUG|===========|Call Trace:|Oops:|detected stalls on CPUs/tasks:|self-detected stall on CPU|Stall ended before state dump start|\?\?\? Writer stall state|rcu_.*kthread starved for' < $file | grep -v 'ODEBUG: ' | grep -v 'Warning: unable to open an initial console' > $1.diags
|
||||
if test -s $1.diags
|
||||
then
|
||||
print_warning Assertion failure in $file $title
|
||||
|
@ -69,6 +69,11 @@ then
|
|||
then
|
||||
summary="$summary Stalls: $n_stalls"
|
||||
fi
|
||||
n_starves=`grep -c 'rcu_.*kthread starved for' $1`
|
||||
if test "$n_starves" -ne 0
|
||||
then
|
||||
summary="$summary Starves: $n_starves"
|
||||
fi
|
||||
print_warning Summary: $summary
|
||||
else
|
||||
rm $1.diags
|
||||
|
|
|
@ -13,6 +13,22 @@ cd initrd
|
|||
cpio -id < /tmp/initrd.img.zcat
|
||||
------------------------------------------------------------------------
|
||||
|
||||
Another way to create an initramfs image is using "dracut"[1], which is
|
||||
available on many distros, however the initramfs dracut generates is a cpio
|
||||
archive with another cpio archive in it, so an extra step is needed to create
|
||||
the initrd directory hierarchy.
|
||||
|
||||
Here are the commands to create a initrd directory for rcutorture using
|
||||
dracut:
|
||||
|
||||
------------------------------------------------------------------------
|
||||
dracut --no-hostonly --no-hostonly-cmdline --module "base bash shutdown" /tmp/initramfs.img
|
||||
cd tools/testing/selftests/rcutorture
|
||||
mkdir initrd
|
||||
cd initrd
|
||||
/usr/lib/dracut/skipcpio /tmp/initramfs.img | zcat | cpio -id < /tmp/initramfs.img
|
||||
------------------------------------------------------------------------
|
||||
|
||||
Interestingly enough, if you are running rcutorture, you don't really
|
||||
need userspace in many cases. Running without userspace has the
|
||||
advantage of allowing you to test your kernel independently of the
|
||||
|
@ -89,3 +105,9 @@ while :
|
|||
do
|
||||
sleep 10
|
||||
done
|
||||
------------------------------------------------------------------------
|
||||
|
||||
References:
|
||||
[1]: https://dracut.wiki.kernel.org/index.php/Main_Page
|
||||
[2]: http://blog.elastocloud.org/2015/06/rapid-linux-kernel-devtest-with-qemu.html
|
||||
[3]: https://www.centos.org/forums/viewtopic.php?t=51621
|
||||
|
|
Loading…
Reference in a new issue