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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2011-04-05 17:23:48 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-04-14 08:52:37 +0200 |
| commit | 3fe1698b7fe05aeb063564e71e40d09f28d8e80c (patch) | |
| tree | d068bd6a075cd85c64a040cf9fc8e661f8be00a8 /kernel/sched_fair.c | |
| parent | 74f8e4b2335de45485b8d5b31a504747f13c8070 (diff) | |
| download | lwn-3fe1698b7fe05aeb063564e71e40d09f28d8e80c.tar.gz lwn-3fe1698b7fe05aeb063564e71e40d09f28d8e80c.zip | |
sched: Deal with non-atomic min_vruntime reads on 32bits
In order to avoid reading partial updated min_vruntime values on 32bit
implement a seqcount like solution.
Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110405152729.111378493@chello.nl
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched_fair.c')
| -rw-r--r-- | kernel/sched_fair.c | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index ad4c414f456d..054cebb81f7b 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -358,6 +358,10 @@ static void update_min_vruntime(struct cfs_rq *cfs_rq) } cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime); +#ifndef CONFIG_64BIT + smp_wmb(); + cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; +#endif } /* @@ -1376,10 +1380,21 @@ static void task_waking_fair(struct task_struct *p) { struct sched_entity *se = &p->se; struct cfs_rq *cfs_rq = cfs_rq_of(se); + u64 min_vruntime; - lockdep_assert_held(&task_rq(p)->lock); +#ifndef CONFIG_64BIT + u64 min_vruntime_copy; - se->vruntime -= cfs_rq->min_vruntime; + do { + min_vruntime_copy = cfs_rq->min_vruntime_copy; + smp_rmb(); + min_vruntime = cfs_rq->min_vruntime; + } while (min_vruntime != min_vruntime_copy); +#else + min_vruntime = cfs_rq->min_vruntime; +#endif + + se->vruntime -= min_vruntime; } #ifdef CONFIG_FAIR_GROUP_SCHED |