From nobody Thu Apr 25 13:35:46 2024 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1CFEEC433F5 for ; Tue, 24 May 2022 04:49:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234508AbiEXEtQ (ORCPT ); Tue, 24 May 2022 00:49:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60818 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232834AbiEXEtM (ORCPT ); Tue, 24 May 2022 00:49:12 -0400 Received: from zg8tmtyylji0my4xnjqumte4.icoremail.net (zg8tmtyylji0my4xnjqumte4.icoremail.net [162.243.164.118]) by lindbergh.monkeyblade.net (Postfix) with SMTP id 4535962215 for ; Mon, 23 May 2022 21:49:09 -0700 (PDT) Received: from ubuntu.localdomain (unknown [124.236.130.193]) by mail-app3 (Coremail) with SMTP id cC_KCgDX36OqY4xig7u_AA--.14600S2; Tue, 24 May 2022 12:48:55 +0800 (CST) From: Duoming Zhou To: linux-mtd@lists.infradead.org Cc: miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com, linux-kernel@vger.kernel.org, Duoming Zhou Subject: [PATCH] mtd: Fix deadlock caused by cancel_work_sync in sm_release Date: Tue, 24 May 2022 12:48:41 +0800 Message-Id: <20220524044841.10517-1-duoming@zju.edu.cn> X-Mailer: git-send-email 2.17.1 X-CM-TRANSID: cC_KCgDX36OqY4xig7u_AA--.14600S2 X-Coremail-Antispam: 1UD129KBjvJXoW7ZFW5XrWkWFy8Zr1DZw1DZFb_yoW8Jw1Dpr WrCry8JFW8Ar4DJ34DKa13ZF4ru34kKFW7Kr1UK3W5ZrZ5XFnIg345KFyFgFWfGFy8A39I vFs2grW5ZF1rZw7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkq14x267AKxVWUJVW8JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_JrI_JrylYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lc2xSY4AK67AK6r45 MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr 0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUAVWUtwCIc40Y0x0E wIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVWUJV W8JwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAI cVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7VUjX4S5UUUUU== X-CM-SenderInfo: qssqjiasttq6lmxovvfxof0/1tbiAgQAAVZdtZ1wIAAZst Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" There is a deadlock between sm_release and sm_cache_flush_work which is a work item. The cancel_work_sync in sm_release will not return until sm_cache_flush_work is finished. If we hold mutex_lock and use cancel_work_sync to wait the work item to finish, the work item also requires mutex_lock. As a result, the sm_release will be blocked forever. The race condition is shown below: (Thread 1) | (Thread 2) sm_release | mutex_lock(&ftl->mutex) | sm_cache_flush_work | mutex_lock(&ftl->mutex) cancel_work_sync | ... This patch moves del_timer_sync and cancel_work_sync out of mutex_lock in order to mitigate deadlock. Fixes: 7d17c02a01a1 ("mtd: Add new SmartMedia/xD FTL") Signed-off-by: Duoming Zhou --- drivers/mtd/sm_ftl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/mtd/sm_ftl.c b/drivers/mtd/sm_ftl.c index 0cff2cda1b5..7f955fade83 100644 --- a/drivers/mtd/sm_ftl.c +++ b/drivers/mtd/sm_ftl.c @@ -1111,9 +1111,9 @@ static void sm_release(struct mtd_blktrans_dev *dev) { struct sm_ftl *ftl =3D dev->priv; =20 - mutex_lock(&ftl->mutex); del_timer_sync(&ftl->timer); cancel_work_sync(&ftl->flush_work); + mutex_lock(&ftl->mutex); sm_cache_flush(ftl); mutex_unlock(&ftl->mutex); } --=20 2.17.1