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authorIngo Molnar <mingo@elte.hu>2006-07-03 00:24:58 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-07-03 15:27:05 -0700
commita0f1ccfd8d37457a6d8a9e01acebeefcdfcc306e (patch)
treee16b7fe211c8ed685bed942910e2ace06e7c2e27 /kernel
parent3047e99ede366298c6233d1870d12a520d4d92f3 (diff)
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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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/printk.c23
1 files changed, 18 insertions, 5 deletions
diff --git a/kernel/printk.c b/kernel/printk.c
index 39ae24d..bdba5d8 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -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);