Messages in this thread | | | Date | Fri, 18 Sep 2015 13:35:39 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] sched: access local runqueue directly in single_task_running |
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On Fri, Sep 18, 2015 at 01:26:53PM +0200, Paolo Bonzini wrote: > > +++ b/kernel/sched/core.c > > @@ -2614,13 +2614,13 @@ unsigned long nr_running(void) > > > > /* > > * Check if only the current task is running on the cpu. > > + * > > + * Caution result is subject to time-of-check-to-time-of-use race, > > + * every caller is responsible to set up additional fences if necessary. > > Let's expand it a bit more: > > * Caution: this function does not check that the caller has disabled > * preemption, thus the result might have a time-of-check-to-time-of-use > * race. The caller is responsible to use this correctly, for example: > * > * - use it from a non-preemptable section > * > * - use it from a thread that is bound to a single CPU > * > * - use it in a loop where each iteration takes very little time > * (e.g. a polling loop) > */ > > I'll include it in my pull request.
In which case:
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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