Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759211Ab3GaJBm (ORCPT ); Wed, 31 Jul 2013 05:01:42 -0400 Received: from terminus.zytor.com ([198.137.202.10]:41713 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755275Ab3GaI4Y (ORCPT ); Wed, 31 Jul 2013 04:56:24 -0400 Date: Wed, 31 Jul 2013 01:55:38 -0700 From: tip-bot for Maarten Lankhorst Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, torvalds@linux-foundation.org, peterz@infradead.org, akpm@linux-foundation.org, alexander.deucher@amd.com, tglx@linutronix.de, maarten.lankhorst@canonical.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, peterz@infradead.org, akpm@linux-foundation.org, alexander.deucher@amd.com, tglx@linutronix.de, maarten.lankhorst@canonical.com In-Reply-To: <51F775B5.201@canonical.com> References: <51F775B5.201@canonical.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:core/urgent] mutex: Fix w/w mutex deadlock injection Git-Commit-ID: 85f4896123d0299128f2c95cc40f3b8b01d4b0f6 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Wed, 31 Jul 2013 01:55:44 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2214 Lines: 54 Commit-ID: 85f4896123d0299128f2c95cc40f3b8b01d4b0f6 Gitweb: http://git.kernel.org/tip/85f4896123d0299128f2c95cc40f3b8b01d4b0f6 Author: Maarten Lankhorst AuthorDate: Tue, 30 Jul 2013 10:13:41 +0200 Committer: Ingo Molnar CommitDate: Tue, 30 Jul 2013 22:16:40 +0200 mutex: Fix w/w mutex deadlock injection 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. Signed-off-by: Maarten Lankhorst Signed-off-by: Peter Zijlstra Cc: Alex Deucher Cc: Linus Torvalds Cc: Andrew Morton Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/51F775B5.201@canonical.com Signed-off-by: Ingo Molnar --- kernel/mutex.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) 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/