Messages in this thread | | | Subject | Re: [PATCH v2 2/3] mutex: add support for reservation style locks, v2 | From | Peter Zijlstra <> | Date | Thu, 04 Apr 2013 18:38:36 +0200 |
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On Thu, 2013-04-04 at 15:31 +0200, Daniel Vetter wrote: > Hm, I guess your aim with the TASK_DEADLOCK wakeup is to bound the > wait > times of older task.
No, imagine the following:
struct ww_mutex A, B; struct mutex C;
task-O task-Y task-X A B C C B
At this point O finds that Y owns B and thus we want to make Y 'yield' B to make allow B progress. Since Y is blocked, we'll send a wakeup. However Y is blocked on a different locking primitive; one that doesn't collaborate in the -EDEADLK scheme therefore we don't want the wakeup to succeed.
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