Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755916Ab3G3NJi (ORCPT ); Tue, 30 Jul 2013 09:09:38 -0400 Received: from mail-vb0-f41.google.com ([209.85.212.41]:40291 "EHLO mail-vb0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755678Ab3G3NJe (ORCPT ); Tue, 30 Jul 2013 09:09:34 -0400 MIME-Version: 1.0 In-Reply-To: <51F775B5.201@canonical.com> References: <20130701082221.GA14112@gmail.com> <51D3C4C8.8060701@canonical.com> <20130705062345.GA29487@gmail.com> <51F775B5.201@canonical.com> Date: Tue, 30 Jul 2013 09:09:33 -0400 Message-ID: Subject: Re: [PATCH] mutex: fix deadlock injection From: Alex Deucher To: Maarten Lankhorst Cc: Ingo Molnar , Peter Zijlstra , Linus Torvalds , Linux Kernel Mailing List , "dri-devel@lists.freedesktop.org" , Alex Deucher , Thomas Gleixner , Andrew Morton Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2056 Lines: 47 On Tue, Jul 30, 2013 at 4:13 AM, Maarten Lankhorst wrote: > The check needs to be for > 1, because ctx->acquired is already incremented. > This will prevent ww_mutex_lock_slow from returning -EDEADLK and not locking > the mutex. It caused a lot of false gpu lockups on radeon with > CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y because a function that shouldn't be able > to return -EDEADLK did. > I haven't followed the new reservation stuff too closely, but seems plausible. Acked-by: Alex Deucher > Cc: Alex Deucher > Signed-off-by: Maarten Lankhorst > --- > diff --git a/kernel/mutex.c b/kernel/mutex.c > index ff05f4b..a52ee7bb 100644 > --- a/kernel/mutex.c > +++ b/kernel/mutex.c > @@ -686,7 +686,7 @@ __ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) > might_sleep(); > ret = __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE, > 0, &ctx->dep_map, _RET_IP_, ctx); > - if (!ret && ctx->acquired > 0) > + if (!ret && ctx->acquired > 1) > return ww_mutex_deadlock_injection(lock, ctx); > > return ret; > @@ -702,7 +702,7 @@ __ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) > ret = __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE, > 0, &ctx->dep_map, _RET_IP_, ctx); > > - if (!ret && ctx->acquired > 0) > + if (!ret && ctx->acquired > 1) > return ww_mutex_deadlock_injection(lock, ctx); > > return ret; > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/dri-devel -- 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/