alistair23-linux/include/linux/debug_locks.h
Paul Walmsley dbf520a9d7 Revert "lockdep: check that no locks held at freeze time"
This reverts commit 6aa9707099.

Commit 6aa9707099 ("lockdep: check that no locks held at freeze time")
causes problems with NFS root filesystems.  The failures were noticed on
OMAP2 and 3 boards during kernel init:

  [ BUG: swapper/0/1 still has locks held! ]
  3.9.0-rc3-00344-ga937536 #1 Not tainted
  -------------------------------------
  1 lock held by swapper/0/1:
   #0:  (&type->s_umount_key#13/1){+.+.+.}, at: [<c011e84c>] sget+0x248/0x574

  stack backtrace:
    rpc_wait_bit_killable
    __wait_on_bit
    out_of_line_wait_on_bit
    __rpc_execute
    rpc_run_task
    rpc_call_sync
    nfs_proc_get_root
    nfs_get_root
    nfs_fs_mount_common
    nfs_try_mount
    nfs_fs_mount
    mount_fs
    vfs_kern_mount
    do_mount
    sys_mount
    do_mount_root
    mount_root
    prepare_namespace
    kernel_init_freeable
    kernel_init

Although the rootfs mounts, the system is unstable.  Here's a transcript
from a PM test:

  http://www.pwsan.com/omap/testlogs/test_v3.9-rc3/20130317194234/pm/37xxevm/37xxevm_log.txt

Here's what the test log should look like:

  http://www.pwsan.com/omap/testlogs/test_v3.8/20130218214403/pm/37xxevm/37xxevm_log.txt

Mailing list discussion is here:

  http://lkml.org/lkml/2013/3/4/221

Deal with this for v3.9 by reverting the problem commit, until folks can
figure out the right long-term course of action.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Mandeep Singh Baines <msb@chromium.org>
Cc: Jeff Layton <jlayton@redhat.com>
Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: <maciej.rutecki@gmail.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ben Chan <benchan@chromium.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-03-31 11:38:33 -07:00

76 lines
1.5 KiB
C

#ifndef __LINUX_DEBUG_LOCKING_H
#define __LINUX_DEBUG_LOCKING_H
#include <linux/kernel.h>
#include <linux/atomic.h>
#include <linux/bug.h>
struct task_struct;
extern int debug_locks;
extern int debug_locks_silent;
static inline int __debug_locks_off(void)
{
return xchg(&debug_locks, 0);
}
/*
* Generic 'turn off all lock debugging' function:
*/
extern int debug_locks_off(void);
#define DEBUG_LOCKS_WARN_ON(c) \
({ \
int __ret = 0; \
\
if (!oops_in_progress && unlikely(c)) { \
if (debug_locks_off() && !debug_locks_silent) \
WARN_ON(1); \
__ret = 1; \
} \
__ret; \
})
#ifdef CONFIG_SMP
# define SMP_DEBUG_LOCKS_WARN_ON(c) DEBUG_LOCKS_WARN_ON(c)
#else
# define SMP_DEBUG_LOCKS_WARN_ON(c) do { } while (0)
#endif
#ifdef CONFIG_DEBUG_LOCKING_API_SELFTESTS
extern void locking_selftest(void);
#else
# define locking_selftest() do { } while (0)
#endif
struct task_struct;
#ifdef CONFIG_LOCKDEP
extern void debug_show_all_locks(void);
extern void debug_show_held_locks(struct task_struct *task);
extern void debug_check_no_locks_freed(const void *from, unsigned long len);
extern void debug_check_no_locks_held(struct task_struct *task);
#else
static inline void debug_show_all_locks(void)
{
}
static inline void debug_show_held_locks(struct task_struct *task)
{
}
static inline void
debug_check_no_locks_freed(const void *from, unsigned long len)
{
}
static inline void
debug_check_no_locks_held(struct task_struct *task)
{
}
#endif
#endif