Merge tag 'platform-drivers-x86-v4.12-2' of git://git.infradead.org/linux-platform...

[karo-tx-linux.git] / kernel / locking / rtmutex.c

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index b9550941690915bc23323cd772e060cda7d3a704..28cd09e635ed669fe6c93b28eb1d59e46bbf4615 100644 (file)
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1785,12 +1785,14 @@ int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
        int ret;
 
        raw_spin_lock_irq(&lock->wait_lock);
-
-       set_current_state(TASK_INTERRUPTIBLE);
-
        /* sleep on the mutex */
+       set_current_state(TASK_INTERRUPTIBLE);
        ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter);
-
+       /*
+        * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
+        * have to fix that up.
+        */
+       fixup_rt_mutex_waiters(lock);
        raw_spin_unlock_irq(&lock->wait_lock);
 
        return ret;
@@ -1821,16 +1823,26 @@ bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
        bool cleanup = false;
 
        raw_spin_lock_irq(&lock->wait_lock);
+       /*
+        * Do an unconditional try-lock, this deals with the lock stealing
+        * state where __rt_mutex_futex_unlock() -> mark_wakeup_next_waiter()
+        * sets a NULL owner.
+        *
+        * We're not interested in the return value, because the subsequent
+        * test on rt_mutex_owner() will infer that. If the trylock succeeded,
+        * we will own the lock and it will have removed the waiter. If we
+        * failed the trylock, we're still not owner and we need to remove
+        * ourselves.
+        */
+       try_to_take_rt_mutex(lock, current, waiter);
        /*
         * Unless we're the owner; we're still enqueued on the wait_list.
         * So check if we became owner, if not, take us off the wait_list.
         */
        if (rt_mutex_owner(lock) != current) {
                remove_waiter(lock, waiter);
-               fixup_rt_mutex_waiters(lock);
                cleanup = true;
        }
-
        /*
         * try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
         * have to fix that up.