Patch "perf/core: Fix __perf_read_group_add() locking" has been added to the 4.14-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    perf/core: Fix __perf_read_group_add() locking

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     perf-core-fix-__perf_read_group_add-locking.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Wed Dec  6 18:04:41 CET 2017
From: Peter Zijlstra <peterz@infradead.org>
Date: Tue, 5 Sep 2017 13:38:24 +0200
Subject: perf/core: Fix __perf_read_group_add() locking

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)


Patches currently in stable-queue which might be from peterz@infradead.org are

queue-4.14/perf-tools-fix-leaking-rec_argv-in-error-cases.patch
queue-4.14/locking-refcounts-x86-asm-use-unique-.text-section-for-refcount-exceptions.patch
queue-4.14/selftests-x86-ldt_get-add-a-few-additional-tests-for-limits.patch
queue-4.14/mm-x86-mm-fix-performance-regression-in-get_user_pages_fast.patch
queue-4.14/selftests-x86-ldt_gdt-robustify-against-set_thread_area-and-lar-oddities.patch
queue-4.14/kprobes-use-synchronize_rcu_tasks-for-optprobe-with-config_preempt-y.patch
queue-4.14/x86-entry-use-syscall_define-macros-for-sys_modify_ldt.patch
queue-4.14/kprobes-x86-disable-preemption-in-ftrace-based-jprobes.patch
queue-4.14/locking-refcounts-x86-asm-enable-config_arch_has_refcount.patch
queue-4.14/perf-core-fix-__perf_read_group_add-locking.patch