From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755589AbZCLH5Y (ORCPT ); Thu, 12 Mar 2009 03:57:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755098AbZCLH4M (ORCPT ); Thu, 12 Mar 2009 03:56:12 -0400 Received: from e37.co.us.ibm.com ([32.97.110.158]:49003 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755025AbZCLH4L (ORCPT ); Thu, 12 Mar 2009 03:56:11 -0400 From: Darren Hart Subject: [PATCH 5/6] futex: unlock before returning -EFAULT To: linux-kernel@vger.kernel.org Cc: Thomas Gleixner , Peter Zijlstra , Ingo Molnar , Rusty Russell , Darren Hart , Thomas Gleixner , Peter Zijlstra , Ingo Molnar , Rusty Russell Date: Thu, 12 Mar 2009 00:56:06 -0700 Message-ID: <20090312075606.9856.88729.stgit@Aeon> In-Reply-To: <20090312075349.9856.83687.stgit@Aeon> References: <20090312075349.9856.83687.stgit@Aeon> User-Agent: StGIT/0.14.2 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org futex_lock_pi can potentially return -EFAULT with the rt_mutex held. This seems like the wrong thing to do as userspace should assume -EFAULT means the lock was not taken. Even if it could figure this out, we'd be leaving the pi_state->owner in an inconsistent state. This patch unlocks the rt_mutex prior to returning -EFAULT to userspace. Build and boot tested on a 4 way Intel x86_64 workstation. Passes basic pthread_mutex and PI tests out of ltp/testcases/realtime. Signed-off-by: Darren Hart Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Rusty Russell --- kernel/futex.c | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-) diff --git a/kernel/futex.c b/kernel/futex.c index 6579912..c980a55 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1567,6 +1567,13 @@ retry_locked: } } + /* + * If fixup_pi_state_owner() faulted and was unable to handle the + * fault, unlock it and return the fault to userspace. + */ + if (ret && (rt_mutex_owner(&q.pi_state->pi_mutex) == current)) + rt_mutex_unlock(&q.pi_state->pi_mutex); + /* Unqueue and drop the lock */ unqueue_me_pi(&q);