Messages in this thread | | | Date | Thu, 11 Nov 2021 14:52:19 -0500 | Subject | Re: [BUG]locking/rwsem: only clean RWSEM_FLAG_HANDOFF when already set | From | Waiman Long <> |
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On 11/11/21 14:36, Waiman Long wrote: > > On 11/11/21 14:20, Peter Zijlstra wrote: >> On Thu, Nov 11, 2021 at 02:14:48PM -0500, Waiman Long wrote: >>> As for the PHASE_CHANGE name, we have to be consistent in both rwsem >>> and >>> mutex. Maybe a follow up patch if you think we should change the >>> terminology. >> Well, that's exactly the point, they do radically different things. >> Having the same name for two different things is confusing. >> >> Anyway, let me go read that patch you sent. > > My understanding of handoff is to disable optimistic spinning to let > waiters in the wait queue have an opportunity to acquire the lock. > There are difference in details on how to do that in mutex and rwsem, > though. > > BTW, I have decided that we should further simply the trylock for loop > in rwsem_down_write_slowpath() to make it easier to read. That is the > only difference in the attached v2 patch compared with the previous one.
My bad, I forgot to initialize waiter.handoff_set in rwsem_down_write_slowpath(). I will send out an updated version once you have finished your review.
Cheers, Longman
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