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| author |   Peter Zijlstra <peterz@infradead.org> | 2018-03-27 14:14:38 +0200 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2018-03-28 23:01:30 +0200 |
| commit | c28d62cf52d791ba5f6db7ce525ed06b86291c82 (patch) | |
| tree | 683f0b9f5b8faa613a46da023b1b7a4bd204c33e /kernel/locking/rtmutex.c | |
| parent | locking/atomic, asm-generic, x86: Add comments for atomic instrumentation (diff) | |
| download | wireguard-linux-c28d62cf52d791ba5f6db7ce525ed06b86291c82.tar.xz wireguard-linux-c28d62cf52d791ba5f6db7ce525ed06b86291c82.zip | |
locking/rtmutex: Handle non enqueued waiters gracefully in remove_waiter()
In -RT task_blocks_on_rt_mutex() may return with -EAGAIN due to
(->pi_blocked_on == PI_WAKEUP_INPROGRESS) before it added itself as a
waiter. In such a case remove_waiter() must not be called because without a
waiter it will trigger the BUG_ON() statement.
This was initially reported by Yimin Deng. Thomas Gleixner fixed it then
with an explicit check for waiters before calling remove_waiter().
Instead of an explicit NULL check before calling rt_mutex_top_waiter() make
the function return NULL if there are no waiters. With that fixed the now
pointless NULL check is removed from rt_mutex_slowlock().
Reported-and-debugged-by: Yimin Deng <yimin11.deng@gmail.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/CAAh1qt=DCL9aUXNxanP5BKtiPp3m+qj4yB+gDohhXPVFCxWwzg@mail.gmail.com
Link: https://lkml.kernel.org/r/20180327121438.sss7hxg3crqy4ecd@linutronix.de
Diffstat (limited to 'kernel/locking/rtmutex.c')
| -rw-r--r-- | kernel/locking/rtmutex.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 940633c63254..4f014be7a4b8 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -1268,8 +1268,7 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state, if (unlikely(ret)) { __set_current_state(TASK_RUNNING); - if (rt_mutex_has_waiters(lock)) - remove_waiter(lock, &waiter); + remove_waiter(lock, &waiter); rt_mutex_handle_deadlock(ret, chwalk, &waiter); } |