lkml.org 
[lkml]   [2016]   [Feb]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v2 1/4] locking/mutex: Add waiter parameter to mutex_optimistic_spin()
    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

    \
     
     \ /
      Last update: 2016-02-12 23:21    [W:5.617 / U:0.020 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site