Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759331AbcLAOIJ (ORCPT ); Thu, 1 Dec 2016 09:08:09 -0500 Received: from mail-wm0-f66.google.com ([74.125.82.66]:33674 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757961AbcLAOHM (ORCPT ); Thu, 1 Dec 2016 09:07:12 -0500 From: =?UTF-8?q?Nicolai=20H=C3=A4hnle?= To: linux-kernel@vger.kernel.org Cc: =?UTF-8?q?Nicolai=20H=C3=A4hnle?= , Peter Zijlstra , Ingo Molnar , Maarten Lankhorst , Daniel Vetter , Chris Wilson , dri-devel@lists.freedesktop.org Subject: [PATCH v2 09/11] locking/mutex: Initialize mutex_waiter::ww_ctx with poison when debugging Date: Thu, 1 Dec 2016 15:06:52 +0100 Message-Id: <1480601214-26583-10-git-send-email-nhaehnle@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1480601214-26583-1-git-send-email-nhaehnle@gmail.com> References: <1480601214-26583-1-git-send-email-nhaehnle@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1628 Lines: 46 From: Nicolai Hähnle Help catch cases where mutex_lock is used directly on w/w mutexes, which otherwise result in the w/w tasks reading uninitialized data. Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Maarten Lankhorst Cc: Daniel Vetter Cc: Chris Wilson Cc: dri-devel@lists.freedesktop.org Signed-off-by: Nicolai Hähnle --- include/linux/poison.h | 1 + kernel/locking/mutex.c | 4 ++++ 2 files changed, 5 insertions(+) diff --git a/include/linux/poison.h b/include/linux/poison.h index 51334ed..a395403 100644 --- a/include/linux/poison.h +++ b/include/linux/poison.h @@ -80,6 +80,7 @@ /********** kernel/mutexes **********/ #define MUTEX_DEBUG_INIT 0x11 #define MUTEX_DEBUG_FREE 0x22 +#define MUTEX_POISON_WW_CTX ((void *) 0x500 + POISON_POINTER_DELTA) /********** lib/flex_array.c **********/ #define FLEX_ARRAY_FREE 0x6c /* for use-after-free poisoning */ diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index 296605c..38d173c 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -794,6 +794,10 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, if (!use_ww_ctx) { /* add waiting tasks to the end of the waitqueue (FIFO): */ list_add_tail(&waiter.list, &lock->wait_list); + +#ifdef CONFIG_DEBUG_MUTEXES + waiter.ww_ctx = MUTEX_POISON_WW_CTX; +#endif } else { /* Add in stamp order, waking up waiters that must back off. */ ret = __ww_mutex_add_waiter(&waiter, lock, ww_ctx); -- 2.7.4