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[PATCH] lockdep: do not recurse in printk 

Make printk()-ing from within the lock validation code safer by using the
lockdep-recursion counter.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Ingo Molnar 2006-07-03 00:24:58 -07:00 committed by Linus Torvalds
parent 3047e99ede
commit a0f1ccfd8d
1 changed files with 18 additions and 5 deletions
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23
kernel/printk.c
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@ -518,7 +518,9 @@ asmlinkage int vprintk(const char *fmt, va_list args)
zap_locks();
/* This stops the holder of console_sem just where we want him */
spin_lock_irqsave(&logbuf_lock, flags);
local_irq_save(flags);
lockdep_off();
spin_lock(&logbuf_lock);
printk_cpu = smp_processor_id();
/* Emit the output into the temporary buffer */
@ -588,7 +590,7 @@ asmlinkage int vprintk(const char *fmt, va_list args)
*/
console_locked = 1;
printk_cpu = UINT_MAX;
spin_unlock_irqrestore(&logbuf_lock, flags);
spin_unlock(&logbuf_lock);
/*
* Console drivers may assume that per-cpu resources have
@ -604,6 +606,8 @@ asmlinkage int vprintk(const char *fmt, va_list args)
console_locked = 0;
up(&console_sem);
}
lockdep_on();
local_irq_restore(flags);
} else {
/*
* Someone else owns the drivers. We drop the spinlock, which
@ -611,7 +615,9 @@ asmlinkage int vprintk(const char *fmt, va_list args)
* console drivers with the output which we just produced.
*/
printk_cpu = UINT_MAX;
spin_unlock_irqrestore(&logbuf_lock, flags);
spin_unlock(&logbuf_lock);
lockdep_on();
local_irq_restore(flags);
}
preempt_enable();
@ -809,8 +815,15 @@ void release_console_sem(void)
console_may_schedule = 0;
up(&console_sem);
spin_unlock_irqrestore(&logbuf_lock, flags);
if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait))
wake_up_interruptible(&log_wait);
if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait)) {
/*
* If we printk from within the lock dependency code,
* from within the scheduler code, then do not lock
* up due to self-recursion:
*/
if (!lockdep_internal())
wake_up_interruptible(&log_wait);
}
}
EXPORT_SYMBOL(release_console_sem);