Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758032Ab3G3INr (ORCPT ); Tue, 30 Jul 2013 04:13:47 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:52442 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753972Ab3G3INo (ORCPT ); Tue, 30 Jul 2013 04:13:44 -0400 Message-ID: <51F775B5.201@canonical.com> Date: Tue, 30 Jul 2013 10:13:41 +0200 From: Maarten Lankhorst User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130623 Thunderbird/17.0.7 MIME-Version: 1.0 To: Ingo Molnar CC: Linus Torvalds , Linux Kernel Mailing List , Peter Zijlstra , Thomas Gleixner , Andrew Morton , Dave Airlie , "dri-devel@lists.freedesktop.org" , Alex Deucher Subject: [PATCH] mutex: fix deadlock injection References: <20130701082221.GA14112@gmail.com> <51D3C4C8.8060701@canonical.com> <20130705062345.GA29487@gmail.com> In-Reply-To: <20130705062345.GA29487@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1475 Lines: 36 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. 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; -- 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/