Commit 94d24fc4 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

printk, lockdep: Disable lock debugging on zap_locks() 



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: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-kqxwmo4xz37e1s8w0xopvr0q@git.kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 7f80850d

include/linux/lockdep.h

+4 −0
Original line number Original line Diff line number Diff line
@@ -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_assert_held(l)	WARN_ON(debug_locks && !lockdep_is_held(l))





#define lockdep_recursing(tsk)	((tsk)->lockdep_recursion)



#else /* !LOCKDEP */

#else /* !LOCKDEP */





static inline void lockdep_off(void)

static inline void lockdep_off(void)
@@ -392,6 +394,8 @@ struct lock_class_key { }; 




#define lockdep_assert_held(l)			do { } while (0)

#define lockdep_assert_held(l)			do { } while (0)





#define lockdep_recursing(tsk)			(0)



#endif /* !LOCKDEP */

#endif /* !LOCKDEP */





#ifdef CONFIG_LOCK_STAT

#ifdef CONFIG_LOCK_STAT

kernel/printk.c

+2 −1
Original line number Original line Diff line number Diff line
@@ -688,6 +688,7 @@ static void zap_locks(void) 




	oops_timestamp = jiffies;

	oops_timestamp = jiffies;





	debug_locks_off();

	/* If a crash is occurring, make sure we can't deadlock */

	/* If a crash is occurring, make sure we can't deadlock */

	raw_spin_lock_init(&logbuf_lock);

	raw_spin_lock_init(&logbuf_lock);

	/* And make sure that we print immediately */

	/* 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

		 * recursion and return - but flag the recursion so that

		 * it can be printed at the next appropriate moment:

		 * it can be printed at the next appropriate moment:

		 */

		 */

		if (!oops_in_progress) {

		if (!oops_in_progress && !lockdep_recursing(current)) {

			recursion_bug = 1;

			recursion_bug = 1;

			goto out_restore_irqs;

			goto out_restore_irqs;

		}

		}

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