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| author | Thomas Gleixner <tglx@linutronix.de> | 2007-06-08 13:46:58 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-06-08 17:23:34 -0700 |
| commit | 1a539a87280b3032fd12bc93a4a82f1d8aa97ca8 (patch) | |
| tree | 6dea1610ba5ff54f0e3f845d83bfc68ffc162e31 /kernel/rtmutex.c | |
| parent | c0d1d2bf5a28f78def7b68ca1eb5ba31aafd43a1 (diff) | |
| download | lwn-1a539a87280b3032fd12bc93a4a82f1d8aa97ca8.tar.gz lwn-1a539a87280b3032fd12bc93a4a82f1d8aa97ca8.zip | |
rt-mutex: fix chain walk early wakeup bug
Alexey Kuznetsov found some problems in the pi-futex code.
One of the root causes is:
When a wakeup happens, we do not to stop the chain walk so we follow a not
longer relevant locking chain.
Drop out when this happens.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: Ulrich Drepper <drepper@redhat.com>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/rtmutex.c')
| -rw-r--r-- | kernel/rtmutex.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c index a273183c37a0..a6fbb4130521 100644 --- a/kernel/rtmutex.c +++ b/kernel/rtmutex.c @@ -189,6 +189,19 @@ int rt_mutex_adjust_prio_chain(struct task_struct *task, if (!waiter || !waiter->task) goto out_unlock_pi; + /* + * Check the orig_waiter state. After we dropped the locks, + * the previous owner of the lock might have released the lock + * and made us the pending owner: + */ + if (orig_waiter && !orig_waiter->task) + goto out_unlock_pi; + + /* + * Drop out, when the task has no waiters. Note, + * top_waiter can be NULL, when we are in the deboosting + * mode! + */ if (top_waiter && (!task_has_pi_waiters(task) || top_waiter != task_top_pi_waiter(task))) goto out_unlock_pi; |