Commit-ID: a9cd8194e1e6bd09619954721dfaf0f94fe2003e
Gitweb: https://git.kernel.org/tip/a9cd8194e1e6bd09619954721dfaf0f94fe2003e
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Tue, 5 Sep 2017 13:38:24 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 27 Oct 2017 10:31:57 +0200
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@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
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 5fae986..0f34f2a 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)
--
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