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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) <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>
This commit is contained in:
Peter Zijlstra 2017-09-05 13:38:24 +02:00 committed by Ingo Molnar
parent 0ee098c97a
commit a9cd8194e1
1 changed files with 2 additions and 2 deletions
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4
kernel/events/core.c
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@ -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)