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printk, lockdep: Disable lock debugging on zap_locks()

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zap_locks() is used by printk() in a last ditch effort to get data
out, clearly we cannot trust lock state after this so make it disable
lock debugging.

Also don't treat printk recursion through lockdep as a normal
recursion bug but try hard to get the lockdep splat out.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-kqxwmo4xz37e1s8w0xopvr0q@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2011-06-07 11:17:30 +02:00 committed by Ingo Molnar
parent 7f80850d3f
commit 94d24fc472
2 changed files with 6 additions and 1 deletions
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4
include/linux/lockdep.h
View File

@ -343,6 +343,8 @@ extern void lockdep_trace_alloc(gfp_t mask);
#define lockdep_assert_held(l) WARN_ON(debug_locks && !lockdep_is_held(l))
#define lockdep_recursing(tsk) ((tsk)->lockdep_recursion)
#else /* !LOCKDEP */
static inline void lockdep_off(void)
@ -392,6 +394,8 @@ struct lock_class_key { };
#define lockdep_assert_held(l) do { } while (0)
#define lockdep_recursing(tsk) (0)
#endif /* !LOCKDEP */
#ifdef CONFIG_LOCK_STAT

3
kernel/printk.c
View File

@ -688,6 +688,7 @@ static void zap_locks(void)
oops_timestamp = jiffies;
debug_locks_off();
/* If a crash is occurring, make sure we can't deadlock */
raw_spin_lock_init(&logbuf_lock);
/* And make sure that we print immediately */
@ -856,7 +857,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
* recursion and return - but flag the recursion so that
* it can be printed at the next appropriate moment:
*/
if (!oops_in_progress) {
if (!oops_in_progress && !lockdep_recursing(current)) {
recursion_bug = 1;
goto out_restore_irqs;
}