From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752612AbbA0Gt3 (ORCPT ); Tue, 27 Jan 2015 01:49:29 -0500 Received: from mail-wi0-f169.google.com ([209.85.212.169]:47641 "EHLO mail-wi0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751427AbbA0Gt2 (ORCPT ); Tue, 27 Jan 2015 01:49:28 -0500 Message-ID: <1422341364.5145.11.camel@marge.simpson.net> Subject: Re: [PATCH -rt] rtmutex: enable deadlock detection in the ww_mutex_lock functions From: Mike Galbraith To: Gustavo Bittencourt Cc: linux-kernel@vger.kernel.org Date: Tue, 27 Jan 2015 07:49:24 +0100 In-Reply-To: <54C727DA.4040601@gmail.com> References: <54C727DA.4040601@gmail.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org You should probably CC -rt maintainers when submitting a -rt patch. On Tue, 2015-01-27 at 03:53 -0200, Gustavo Bittencourt wrote: > According the ww-mutex-design.txt documentation, the ww_mutex_lock_interruptible and ww_mutex_lock functions should return -EDEADLK when faced with a deadlock. To do so, the flag detect_deadlock in the rt_mutex_slowlock calls should be enabled. This patch corrects potential deadlocks when running PREEMPT_RT with nouveau driver. > > Kernel v3.14-rt > > Signed-off-by: Gustavo Bittencourt > --- > kernel/locking/rtmutex.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c > index 6c40660..3f6ef91 100644 > --- a/kernel/locking/rtmutex.c > +++ b/kernel/locking/rtmutex.c > @@ -1965,7 +1965,7 @@ __ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ww_c > might_sleep(); > > mutex_acquire(&lock->base.dep_map, 0, 0,_RET_IP_); > - ret = rt_mutex_slowlock(&lock->base.lock, TASK_INTERRUPTIBLE, NULL, 0, ww_ctx); > + ret = rt_mutex_slowlock(&lock->base.lock, TASK_INTERRUPTIBLE, NULL, 1, ww_ctx); > if (ret) > mutex_release(&lock->base.dep_map, 1,_RET_IP_); > else if (!ret && ww_ctx->acquired > 1) > @@ -1984,7 +1984,7 @@ __ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ww_ctx) > > mutex_acquire_nest(&lock->base.dep_map, 0, 0, &ww_ctx->dep_map, > _RET_IP_); > - ret = rt_mutex_slowlock(&lock->base.lock, TASK_UNINTERRUPTIBLE, NULL, 0, ww_ctx); > + ret = rt_mutex_slowlock(&lock->base.lock, TASK_UNINTERRUPTIBLE, NULL, 1, ww_ctx); > if (ret) > mutex_release(&lock->base.dep_map, 1,_RET_IP_); > else if (!ret && ww_ctx->acquired > 1) > -- 1.9.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/