| From | alexander.levin@verizon ... | Subject | [PATCH AUTOSEL for 4.14 17/51] perf/core: Fix __perf_read_group_add() locking | Date | Wed, 22 Nov 2017 22:25:40 +0000 |
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From: Peter Zijlstra <peterz@infradead.org>
[ Upstream commit a9cd8194e1e6bd09619954721dfaf0f94fe2003e ]
Event timestamps are serialized using ctx->lock, make sure to hold it over reading all values.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> --- kernel/events/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index 10cdb9c26b5d..4f1d4bfc607a 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4433,6 +4433,8 @@ static int __perf_read_group_add(struct perf_event *leader, if (ret) return ret; + raw_spin_lock_irqsave(&ctx->lock, flags); + /* * Since we co-schedule groups, {enabled,running} times of siblings * will be identical to those of the leader, so we only publish one @@ -4455,8 +4457,6 @@ static int __perf_read_group_add(struct perf_event *leader, if (read_format & PERF_FORMAT_ID) values[n++] = primary_event_id(leader); - raw_spin_lock_irqsave(&ctx->lock, flags); - list_for_each_entry(sub, &leader->sibling_list, group_entry) { values[n++] += perf_event_count(sub); if (read_format & PERF_FORMAT_ID) -- 2.11.0
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