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Subject[PATCH 4.14 31/75] perf/core: Fix __perf_read_group_add() locking
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

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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