From 5afcdab706d6002cb02b567ba46e650215e694e8 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 27 Nov 2009 14:12:25 +0100 Subject: sched: Remove rq->clock coupling from set_task_cpu() set_task_cpu() should be rq invariant and only touch task state, it currently fails to do so, which opens up a few races, since not all callers hold both rq->locks. Remove the relyance on rq->clock, as any site calling set_task_cpu() should also do a remote clock update, which should ensure the observed time between these two cpus is monotonic, as per kernel/sched_clock.c:sched_clock_remote(). Therefore we can simply remove the clock_offset bits and be happy. Signed-off-by: Peter Zijlstra LKML-Reference: Signed-off-by: Ingo Molnar --- kernel/sched.c | 13 +------------ 1 file changed, 1 insertion(+), 12 deletions(-) (limited to 'kernel') diff --git a/kernel/sched.c b/kernel/sched.c index 01fd131b47a4..1f9c6d99f15d 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2060,23 +2060,12 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd) void set_task_cpu(struct task_struct *p, unsigned int new_cpu) { int old_cpu = task_cpu(p); - struct rq *old_rq = cpu_rq(old_cpu), *new_rq = cpu_rq(new_cpu); + struct rq *old_rq = cpu_rq(old_cpu); struct cfs_rq *old_cfsrq = task_cfs_rq(p), *new_cfsrq = cpu_cfs_rq(old_cfsrq, new_cpu); - u64 clock_offset; - - clock_offset = old_rq->clock - new_rq->clock; trace_sched_migrate_task(p, new_cpu); -#ifdef CONFIG_SCHEDSTATS - if (p->se.wait_start) - p->se.wait_start -= clock_offset; - if (p->se.sleep_start) - p->se.sleep_start -= clock_offset; - if (p->se.block_start) - p->se.block_start -= clock_offset; -#endif if (old_cpu != new_cpu) { p->se.nr_migrations++; #ifdef CONFIG_SCHEDSTATS -- cgit v1.2.3-59-g8ed1b