diff options
| -rw-r--r-- | kernel/locking/mutex.c | 30 |
1 files changed, 25 insertions, 5 deletions
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index b4ebd8b9bcd5..8bb2304bb78d 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -631,13 +631,21 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, lock_contended(&lock->dep_map, ip); + set_task_state(task, state); for (;;) { + /* + * Once we hold wait_lock, we're serialized against + * mutex_unlock() handing the lock off to us, do a trylock + * before testing the error conditions to make sure we pick up + * the handoff. + */ if (__mutex_trylock(lock, first)) - break; + goto acquired; /* - * got a signal? (This code gets eliminated in the - * TASK_UNINTERRUPTIBLE case.) + * Check for signals and wound conditions while holding + * wait_lock. This ensures the lock cancellation is ordered + * against mutex_unlock() and wake-ups do not go missing. */ if (unlikely(signal_pending_state(state, task))) { ret = -EINTR; @@ -650,16 +658,27 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, goto err; } - __set_task_state(task, state); spin_unlock_mutex(&lock->wait_lock, flags); schedule_preempt_disabled(); - spin_lock_mutex(&lock->wait_lock, flags); if (!first && __mutex_waiter_is_first(lock, &waiter)) { first = true; __mutex_set_flag(lock, MUTEX_FLAG_HANDOFF); } + + set_task_state(task, state); + /* + * Here we order against unlock; we must either see it change + * state back to RUNNING and fall through the next schedule(), + * or we must see its unlock and acquire. + */ + if (__mutex_trylock(lock, first)) + break; + + spin_lock_mutex(&lock->wait_lock, flags); } + spin_lock_mutex(&lock->wait_lock, flags); +acquired: __set_task_state(task, TASK_RUNNING); mutex_remove_waiter(lock, &waiter, task); @@ -682,6 +701,7 @@ skip_wait: return 0; err: + __set_task_state(task, TASK_RUNNING); mutex_remove_waiter(lock, &waiter, task); spin_unlock_mutex(&lock->wait_lock, flags); debug_mutex_free_waiter(&waiter); |