On Fri, Dec 16, 2016 at 03:19:43PM +0100, Nicolai Hähnle wrote: > The concern about picking up a handoff that we didn't request is real, > though it cannot happen in the first iteration. Perhaps this __mutex_trylock > can be moved to the end of the loop? See below... > >>@@ -728,7 +800,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, > >> * or we must see its unlock and acquire. > >> */ > >> if ((first && mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx, true)) || > >>- __mutex_trylock(lock, first)) > >>+ __mutex_trylock(lock, use_ww_ctx || first)) > >> break; > >> > >> spin_lock_mutex(&lock->wait_lock, flags); > > Change this code to: > > acquired = first && > mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx, > &waiter); > spin_lock_mutex(&lock->wait_lock, flags); > > if (acquired || > __mutex_trylock(lock, use_ww_ctx || first)) > break; goto acquired; will work lots better. > } > > This changes the trylock to always be under the wait_lock, but we previously > had that at the beginning of the loop anyway. > It also removes back-to-back > calls to __mutex_trylock when going through the loop; Yeah, I had that explicitly. It allows taking the mutex when mutex_unlock() is still holding the wait_lock. > and for the first > iteration, there is a __mutex_trylock under wait_lock already before adding > ourselves to the wait list. Correct. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
