Messages in this thread Patch in this message | | | Date | Wed, 14 Sep 2016 12:33:48 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH -v3 07/10] mutex: Restructure wait loop |
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On Fri, Sep 09, 2016 at 04:32:39PM -0400, Waiman Long wrote:
> >I think you need to remove the HANDOFF flag here in the error path too. > >Maybe you should fix that in patch 6. > > > >It is also possible that __mutex_handoff() has been called at this point. > >So this task may now be the owner of the lock. Maybe you should do a final > >trylock here. > > Alternatively, we can move the trylock in the main loop after the > spin_lock_mutex(). In this case, we don't need an extra trylock in the error > path.
I did something like so..
--- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -629,12 +629,12 @@ __mutex_lock_common(struct mutex *lock, if (__mutex_waiter_is_first(lock, &waiter)) __mutex_set_flag(lock, MUTEX_FLAG_WAITERS); - if (__mutex_trylock(lock, false)) - goto remove_waiter; - lock_contended(&lock->dep_map, ip); for (;;) { + if (__mutex_trylock(lock, first)) + break; + /* * got a signal? (This code gets eliminated in the * TASK_UNINTERRUPTIBLE case.) @@ -659,13 +659,9 @@ __mutex_lock_common(struct mutex *lock, first = true; __mutex_set_flag(lock, MUTEX_FLAG_HANDOFF); } - - if (__mutex_trylock(lock, first)) - break; } __set_task_state(task, TASK_RUNNING); -remove_waiter: mutex_remove_waiter(lock, &waiter, task); if (likely(list_empty(&lock->wait_list))) __mutex_clear_flag(lock, MUTEX_FLAGS);
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