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| author | Ingo Molnar <mingo@elte.hu> | 2006-10-11 01:22:08 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-11 11:14:24 -0700 |
| commit | 256a6b41365e17cebe5c2fc91ddff716c9aa055a (patch) | |
| tree | c491008b3e2fefed6a42ac7f824d191e023fb11f /kernel/printk.c | |
| parent | 5fcce7432a731e67f1cd3ef1e71dca9ea84dedb1 (diff) | |
| download | lwn-256a6b41365e17cebe5c2fc91ddff716c9aa055a.tar.gz lwn-256a6b41365e17cebe5c2fc91ddff716c9aa055a.zip | |
[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>
Diffstat (limited to 'kernel/printk.c')
| -rw-r--r-- | kernel/printk.c | 11 |
1 files changed, 2 insertions, 9 deletions
diff --git a/kernel/printk.c b/kernel/printk.c index 771f5e861bcd..f7d427ef5038 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -820,15 +820,8 @@ void release_console_sem(void) 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); |