Messages in this thread Patch in this message |  | | Date | Fri, 10 Oct 2014 11:56:33 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/1] sched: fix the PREEMPT_ACTIVE check in __trace_sched_switch_state() |
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On Fri, Oct 10, 2014 at 11:54:52AM +0200, Peter Zijlstra wrote: > On Tue, Oct 07, 2014 at 09:51:08PM +0200, Oleg Nesterov wrote: > > task_preempt_count() has nothing to do with the actual preempt counter, > > thread_info->saved_preempt_count is only valid right after switch_to(). > > > > __trace_sched_switch_state() can use preempt_count(), prev is still the > > current task when trace_sched_switch() is called. > > This is true, but the paranoid in me would like a BUG_ON(p != current) > right along with that to make sure we don't accidentally change this. > > But yes, its good to get rid of task_preempt_count(), its horrible.
Like so then?
--- --- a/include/trace/events/sched.h +++ b/include/trace/events/sched.h @@ -97,16 +97,19 @@ static inline long __trace_sched_switch_ long state = p->state; #ifdef CONFIG_PREEMPT +#ifdef CONFIG_SCHED_DEBUG + BUG_ON(p != current); +#endif /* CONFIG_SCHED_DEBUG */ /* * For all intents and purposes a preempted task is a running task. */ - if (task_preempt_count(p) & PREEMPT_ACTIVE) + if (preempt_count() & PREEMPT_ACTIVE) state = TASK_RUNNING | TASK_STATE_MAX; -#endif +#endif /* CONFIG_PREEMPT */ return state; } -#endif +#endif /* CREATE_TRACE_POINTS */ /* * Tracepoint for task switches, performed by the scheduler:
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