Messages in this thread | | | Date | Fri, 12 Feb 2016 14:14:44 -0800 | From | Davidlohr Bueso <> | Subject | Re: [PATCH v2 1/4] locking/mutex: Add waiter parameter to mutex_optimistic_spin() |
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On Fri, 12 Feb 2016, Peter Zijlstra wrote:
>On Fri, Feb 12, 2016 at 12:32:12PM -0500, Waiman Long wrote: >> static bool mutex_optimistic_spin(struct mutex *lock, >> + struct ww_acquire_ctx *ww_ctx, >> + const bool use_ww_ctx, int waiter) >> { >> struct task_struct *task = current; >> + bool acquired = false; >> >> + if (!waiter) { >> + if (!mutex_can_spin_on_owner(lock)) >> + goto done; > >Why doesn't the waiter have to check mutex_can_spin_on_owner() ?
afaict because mutex_can_spin_on_owner() fails immediately when the counter is -1, which is a nono for the waiters case.
Thanks, Davidlohr
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