[PATCH] lockdep: fix printk recursion logic
Bug reported and fixed by Tilman Schmidt <tilman@imap.cc>: if lockdep is
enabled then log messages make it to /var/log/messages belatedly. The
reason is a missed wakeup of klogd.
Initially there was only a lockdep_internal() protection against lockdep
recursion within vprintk() - it grew the 'outer' lockdep_off()/on()
protection only later on. But that lockdep_off() made the
release_console_sem() within vprintk() always happen under the
lockdep_internal() condition, causing the bug.
The right solution to remove the inner protection against recursion here -
the outer one is enough.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Tilman Schmidt <tilman@imap.cc>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/printk.c b/kernel/printk.c
index 771f5e8..f7d427e 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -820,15 +820,8 @@
console_locked = 0;
up(&console_sem);
spin_unlock_irqrestore(&logbuf_lock, flags);
- 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);
- }
+ if (wake_klogd && !oops_in_progress && waitqueue_active(&log_wait))
+ wake_up_interruptible(&log_wait);
}
EXPORT_SYMBOL(release_console_sem);
