From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932942Ab1LFG1u (ORCPT ); Tue, 6 Dec 2011 01:27:50 -0500 Received: from terminus.zytor.com ([198.137.202.10]:33921 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932826Ab1LFG1s (ORCPT ); Tue, 6 Dec 2011 01:27:48 -0500 Date: Mon, 5 Dec 2011 22:27:33 -0800 From: tip-bot for Gleb Natapov Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, gleb@redhat.com, rostedt@goodmis.org, tglx@linutronix.de, jbaron@redhat.com Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, gleb@redhat.com, rostedt@goodmis.org, tglx@linutronix.de, jbaron@redhat.com In-Reply-To: <20111018175551.GH17571@redhat.com> References: <20111018175551.GH17571@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] jump_label: jump_label_inc may return before the code is patched Git-Commit-ID: bbbf7af4bf8fc69bc751818cf30521080fa47dcb X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.6 (terminus.zytor.com [127.0.0.1]); Mon, 05 Dec 2011 22:27:40 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: bbbf7af4bf8fc69bc751818cf30521080fa47dcb Gitweb: http://git.kernel.org/tip/bbbf7af4bf8fc69bc751818cf30521080fa47dcb Author: Gleb Natapov AuthorDate: Tue, 18 Oct 2011 19:55:51 +0200 Committer: Steven Rostedt CommitDate: Mon, 5 Dec 2011 13:28:46 -0500 jump_label: jump_label_inc may return before the code is patched If cpu A calls jump_label_inc() just after atomic_add_return() is called by cpu B, atomic_inc_not_zero() will return value greater then zero and jump_label_inc() will return to a caller before jump_label_update() finishes its job on cpu B. Link: http://lkml.kernel.org/r/20111018175551.GH17571@redhat.com Cc: stable@vger.kernel.org Cc: Peter Zijlstra Acked-by: Jason Baron Signed-off-by: Gleb Natapov Signed-off-by: Steven Rostedt --- kernel/jump_label.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/kernel/jump_label.c b/kernel/jump_label.c index bbdfe2a..66ff710 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -66,8 +66,9 @@ void jump_label_inc(struct jump_label_key *key) return; jump_label_lock(); - if (atomic_add_return(1, &key->enabled) == 1) + if (atomic_read(&key->enabled) == 0) jump_label_update(key, JUMP_LABEL_ENABLE); + atomic_inc(&key->enabled); jump_label_unlock(); }