From a9cd8194e1e6bd09619954721dfaf0f94fe2003e Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 5 Sep 2017 13:38:24 +0200 Subject: [PATCH] perf/core: Fix __perf_read_group_add() locking Event timestamps are serialized using ctx->lock, make sure to hold it over reading all values. Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar --- 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 5fae98626b15..0f34f2a47eb6 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4453,6 +4453,8 @@ 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 @@ -4475,8 +4477,6 @@ 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) -- GitLab