From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755087Ab1LGQxJ (ORCPT ); Wed, 7 Dec 2011 11:53:09 -0500 Received: from cantor2.suse.de ([195.135.220.15]:33517 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757523Ab1LGQTk (ORCPT ); Wed, 7 Dec 2011 11:19:40 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Wed Dec 7 08:08:28 2011 Message-Id: <20111207160828.906711000@clark.kroah.org> User-Agent: quilt/0.50-23.1 Date: Wed, 07 Dec 2011 08:07:37 -0800 From: Greg KH To: , Cc: , , , Peter Zijlstra , Jason Baron , Gleb Natapov , Steven Rostedt Subject: [77/80] jump_label: jump_label_inc may return before the code is patched In-Reply-To: <20111207161256.GA7736@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gleb Natapov commit bbbf7af4bf8fc69bc751818cf30521080fa47dcb upstream. 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: Peter Zijlstra Acked-by: Jason Baron Signed-off-by: Gleb Natapov Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- kernel/jump_label.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -66,8 +66,9 @@ void jump_label_inc(struct jump_label_ke 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(); }