| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.14 31/75] perf/core: Fix __perf_read_group_add() locking | Date | Thu, 7 Dec 2017 14:07:53 +0100 |
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4.14-stable review patch. If anyone has any objections, please let me know.
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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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- kernel/events/core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4433,6 +4433,8 @@ static int __perf_read_group_add(struct 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 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)
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