From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933930AbcBZWbd (ORCPT ); Fri, 26 Feb 2016 17:31:33 -0500 Received: from mail.kernel.org ([198.145.29.136]:51712 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423282AbcBZWUK (ORCPT ); Fri, 26 Feb 2016 17:20:10 -0500 Message-Id: <20160226214428.043960999@goodmis.org> User-Agent: quilt/0.61-1 Date: Fri, 26 Feb 2016 16:44:09 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-rt-users Cc: Thomas Gleixner , Carsten Emde , Sebastian Andrzej Siewior , John Kacur , Paul Gortmaker , Subject: [PATCH RT 1/7] rtmutex: Handle non enqueued waiters gracefully References: <20160226214408.590103414@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=0001-rtmutex-Handle-non-enqueued-waiters-gracefully.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.77-rt111-rc1 stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Gleixner Yimin debugged that in case of a PI wakeup in progress when rt_mutex_start_proxy_lock() calls task_blocks_on_rt_mutex() the latter returns -EAGAIN and in consequence the remove_waiter() call runs into a BUG_ON() because there is nothing to remove. Guard it with rt_mutex_has_waiters(). This is a quick fix which is easy to backport. The proper fix is to have a central check in remove_waiter() so we can call it unconditionally. Reported-and-debugged-by: Yimin Deng Signed-off-by: Thomas Gleixner Cc: stable-rt@vger.kernel.org Signed-off-by: Steven Rostedt --- kernel/rtmutex.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c index 52cab2720a06..f074834c1ad6 100644 --- a/kernel/rtmutex.c +++ b/kernel/rtmutex.c @@ -1935,7 +1935,7 @@ int rt_mutex_start_proxy_lock(struct rt_mutex *lock, ret = 0; } - if (unlikely(ret)) + if (ret && rt_mutex_has_waiters(lock)) remove_waiter(lock, waiter); raw_spin_unlock(&lock->wait_lock); -- 2.7.0