Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751920AbcDUKHq (ORCPT ); Thu, 21 Apr 2016 06:07:46 -0400 Received: from terminus.zytor.com ([198.137.202.10]:60042 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751697AbcDUKHo (ORCPT ); Thu, 21 Apr 2016 06:07:44 -0400 Date: Thu, 21 Apr 2016 03:07:01 -0700 From: tip-bot for Romain Perier Message-ID: Cc: mingo@kernel.org, romain.perier@free-electrons.com, tglx@linutronix.de, arnd@arndb.de, peterz@infradead.org, hpa@zytor.com, thomas.petazzoni@free-electrons.com, linux-kernel@vger.kernel.org Reply-To: linux-kernel@vger.kernel.org, thomas.petazzoni@free-electrons.com, hpa@zytor.com, peterz@infradead.org, arnd@arndb.de, tglx@linutronix.de, romain.perier@free-electrons.com, mingo@kernel.org In-Reply-To: <1460640963-690-1-git-send-email-romain.perier@free-electrons.com> References: <1460640963-690-1-git-send-email-romain.perier@free-electrons.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:locking/urgent] asm-generic/futex: Re-enable preemption in futex_atomic_cmpxchg_inatomic() Git-Commit-ID: fba7cd681b6155e2d93e7862fcd6f970336b83c3 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2196 Lines: 57 Commit-ID: fba7cd681b6155e2d93e7862fcd6f970336b83c3 Gitweb: http://git.kernel.org/tip/fba7cd681b6155e2d93e7862fcd6f970336b83c3 Author: Romain Perier AuthorDate: Thu, 14 Apr 2016 15:36:03 +0200 Committer: Thomas Gleixner CommitDate: Thu, 21 Apr 2016 11:06:09 +0200 asm-generic/futex: Re-enable preemption in futex_atomic_cmpxchg_inatomic() The recent decoupling of pagefault disable and preempt disable added an explicit preempt_disable/enable() pair to the futex_atomic_cmpxchg_inatomic() implementation in asm-generic/futex.h. But it forgot to add preempt_enable() calls to the error handling code pathes, which results in a preemption count imbalance. This is observable on boot when the test for atomic_cmpxchg() is calling futex_atomic_cmpxchg_inatomic() on a NULL pointer. Add the missing preempt_enable() calls to the error handling code pathes. [ tglx: Massaged changelog ] Fixes: d9b9ff8c1889 ("sched/preempt, futex: Disable preemption in UP futex_atomic_cmpxchg_inatomic() explicitly") Signed-off-by: Romain Perier Cc: linux-arch@vger.kernel.org Cc: Thomas Petazzoni Cc: Arnd Bergmann Cc: Peter Zijlstra Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1460640963-690-1-git-send-email-romain.perier@free-electrons.com Signed-off-by: Thomas Gleixner --- include/asm-generic/futex.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/include/asm-generic/futex.h b/include/asm-generic/futex.h index e56272c..bf2d34c 100644 --- a/include/asm-generic/futex.h +++ b/include/asm-generic/futex.h @@ -108,11 +108,15 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 val; preempt_disable(); - if (unlikely(get_user(val, uaddr) != 0)) + if (unlikely(get_user(val, uaddr) != 0)) { + preempt_enable(); return -EFAULT; + } - if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) + if (val == oldval && unlikely(put_user(newval, uaddr) != 0)) { + preempt_enable(); return -EFAULT; + } *uval = val; preempt_enable();