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rtmutex: Drop rt_mutex::wait_lock before scheduling

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commit d33d26036a0274b472299d7dcdaa5fb34329f91b upstream.

rt_mutex_handle_deadlock() is called with rt_mutex::wait_lock held.  In the
good case it returns with the lock held and in the deadlock case it emits a
warning and goes into an endless scheduling loop with the lock held, which
triggers the 'scheduling in atomic' warning.

Unlock rt_mutex::wait_lock in the dead lock case before issuing the warning
and dropping into the schedule for ever loop.

[ tglx: Moved unlock before the WARN(), removed the pointless comment,
  	massaged changelog, added Fixes tag ]

Fixes: 3d5c9340d1 ("rtmutex: Handle deadlock detection smarter")
Signed-off-by: Roland Xu <mu001999@outlook.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/ME0P300MB063599BEF0743B8FA339C2CECC802@ME0P300MB0635.AUSP300.PROD.OUTLOOK.COM
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Roland Xu
2024-08-15 10:58:13 +08:00
committed by Greg Kroah-Hartman
parent 76b1dda159
commit 432efdbe7d
1 changed files with 3 additions and 1 deletions
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4
kernel/locking/rtmutex.c
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@@ -1205,6 +1205,7 @@ __rt_mutex_slowlock(struct rt_mutex *lock, int state,
} }
static void rt_mutex_handle_deadlock(int res, int detect_deadlock, static void rt_mutex_handle_deadlock(int res, int detect_deadlock,
struct rt_mutex *lock,
struct rt_mutex_waiter *w) struct rt_mutex_waiter *w)
{ {
/* /*
@@ -1214,6 +1215,7 @@ static void rt_mutex_handle_deadlock(int res, int detect_deadlock,
if (res != -EDEADLOCK || detect_deadlock) if (res != -EDEADLOCK || detect_deadlock)
return; return;
raw_spin_unlock_irq(&lock->wait_lock);
/* /*
* Yell lowdly and stop the task right here. * Yell lowdly and stop the task right here.
*/ */
@@ -1269,7 +1271,7 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
if (unlikely(ret)) { if (unlikely(ret)) {
__set_current_state(TASK_RUNNING); __set_current_state(TASK_RUNNING);
remove_waiter(lock, &waiter); remove_waiter(lock, &waiter);
rt_mutex_handle_deadlock(ret, chwalk, &waiter); rt_mutex_handle_deadlock(ret, chwalk, lock, &waiter);
} }
/* /*