Messages in this thread | | | Date | Wed, 4 May 2016 14:33:03 -0400 | From | Waiman Long <> | Subject | Re: [PATCH] locking/rwsem: Add reader owned state to the owner field |
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On 05/04/2016 01:52 PM, Jason Low wrote: > On Wed, 2016-05-04 at 13:27 -0400, Waiman Long wrote: >> On 05/03/2016 08:21 PM, Davidlohr Bueso wrote: >>> On Wed, 27 Apr 2016, Waiman Long wrote: >>>> static bool rwsem_optimistic_spin(struct rw_semaphore *sem) >>>> @@ -378,7 +367,8 @@ static bool rwsem_optimistic_spin(struct >>>> rw_semaphore *sem) >>>> >>>> while (true) { >>>> owner = READ_ONCE(sem->owner); >>>> - if (owner&& !rwsem_spin_on_owner(sem, owner)) >>>> + if (rwsem_is_writer_owned(owner)&& >>>> + !rwsem_spin_on_owner(sem, owner)) >>>> break; >>>> >>>> /* wait_lock will be acquired if write_lock is obtained */ >>>> @@ -391,9 +381,11 @@ static bool rwsem_optimistic_spin(struct >>>> rw_semaphore *sem) >>>> * When there's no owner, we might have preempted between the >>>> * owner acquiring the lock and setting the owner field. If >>>> * we're an RT task that will live-lock because we won't let >>>> - * the owner complete. >>>> + * the owner complete. We also quit if the lock is owned by >>>> + * readers. >>>> */ >>>> - if (!owner&& (need_resched() || rt_task(current))) >>>> + if ((owner == RWSEM_READER_OWNED) || > It would be good to provide and use a rwsem_is_reader_owned() function > like we do with rwsem_is_writer_owned(), especially if we're going to > add in the additional cast. >
Yes, sure I can certainly add the rwsem_is_reader_owned() helper function.
Cheers, Longman
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