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Commit cebde6d6 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched/core: Validate rq_clock*() serialization 



rq->clock{,_task} are serialized by rq->lock, verify this.

One immediate fail is the usage in scale_rt_capability, so 'annotate'
that for now, there's more 'funny' there. Maybe change rq->lock into a
raw_seqlock_t?

(Only 32-bit is affected)

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150105103554.361872747@infradead.org


Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: umgwanakikbuti@gmail.com
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 1b537c7d

kernel/sched/fair.c

+1 −1
Original line number Diff line number Diff line
@@ -5948,8 +5948,8 @@ static unsigned long scale_rt_capacity(int cpu) 
	 */

	age_stamp = ACCESS_ONCE(rq->age_stamp);

	avg = ACCESS_ONCE(rq->rt_avg);

	delta = __rq_clock_broken(rq) - age_stamp;



	delta = rq_clock(rq) - age_stamp;

	if (unlikely(delta < 0))

		delta = 0;

kernel/sched/sched.h

+7 −0
Original line number Diff line number Diff line
@@ -687,13 +687,20 @@ DECLARE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); 
#define cpu_curr(cpu)		(cpu_rq(cpu)->curr)

#define raw_rq()		raw_cpu_ptr(&runqueues)



static inline u64 __rq_clock_broken(struct rq *rq)

{

	return ACCESS_ONCE(rq->clock);

}



static inline u64 rq_clock(struct rq *rq)

{

	lockdep_assert_held(&rq->lock);

	return rq->clock;

}



static inline u64 rq_clock_task(struct rq *rq)

{

	lockdep_assert_held(&rq->lock);

	return rq->clock_task;

}