Messages in this thread | | | Date | Thu, 18 Aug 2016 16:27:35 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v2] locking/mutex: Prevent lock starvation when spinning is enabled |
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On Wed, Aug 10, 2016 at 11:44:08AM -0700, Jason Low wrote: > @@ -556,8 +604,12 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, > * other waiters. We only attempt the xchg if the count is > * non-negative in order to avoid unnecessary xchg operations: > */ > - if (atomic_read(&lock->count) >= 0 && > + if ((!need_yield_to_waiter(lock) || wakeups > 1) && > + atomic_read(&lock->count) >= 0 && > (atomic_xchg_acquire(&lock->count, -1) == 1)) > + if (wakeups > 1) > + clear_yield_to_waiter(lock); > + > break; > > /*
There's some { } gone missing there...
Also, I think I'll change it to avoid that extra wakeups > 1 condition..
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