From patchwork Sun Apr 17 13:05:43 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Duoming Zhou X-Patchwork-Id: 12815958 X-Patchwork-Delegate: kuba@kernel.org 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 EC673C433EF for ; Sun, 17 Apr 2022 13:06:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234127AbiDQNIh (ORCPT ); Sun, 17 Apr 2022 09:08:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38086 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234110AbiDQNIg (ORCPT ); Sun, 17 Apr 2022 09:08:36 -0400 Received: from zju.edu.cn (spam.zju.edu.cn [61.164.42.155]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 6EE9B3A191; Sun, 17 Apr 2022 06:05:58 -0700 (PDT) Received: from ubuntu.localdomain (unknown [10.15.192.164]) by mail-app4 (Coremail) with SMTP id cS_KCgDn76eoEFxiVqtbAQ--.23203S2; Sun, 17 Apr 2022 21:05:49 +0800 (CST) From: Duoming Zhou To: linux-kernel@vger.kernel.org, wg@grandegger.com, mkl@pengutronix.de Cc: davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, linux-can@vger.kernel.org, netdev@vger.kernel.org, Duoming Zhou Subject: [PATCH] drivers: net: can: Fix deadlock in grcan_close() Date: Sun, 17 Apr 2022 21:05:43 +0800 Message-Id: <20220417130543.90518-1-duoming@zju.edu.cn> X-Mailer: git-send-email 2.17.1 X-CM-TRANSID: cS_KCgDn76eoEFxiVqtbAQ--.23203S2 X-Coremail-Antispam: 1UD129KBjvJXoW7Kr4kXF45Xw1xWr4kWr4kJFb_yoW8Gw4xpw 47KFyfAFWvvr4UK3Z7Xw4kZF1rZ3WDWFWUJFy5Wws5Zwn3ZF15JF1rKa4UuF47KFyDKFsx uF1rXrZ3CFs8GrJanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkI1xkIjI8I6I8E6xAIw20EY4v20xvaj40_Wr0E3s1l1IIY67AE w4v_Jr0_Jr4l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xvwVC0I7IYx2 IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxVWxJr0_GcWl84ACjcxK6I8E 87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_GcCE3s1le2I262IYc4CY6c 8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_JrI_ JrylYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvY0x0EwI xGrwACjI8F5VA0II8E6IAqYI8I648v4I1l42xK82IYc2Ij64vIr41l42xK82IY6x8ErcxF aVAv8VW8uw4UJr1UMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr 4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxG rwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJw CI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2 z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7VU1a9aPUUUUU== X-CM-SenderInfo: qssqjiasttq6lmxovvfxof0/1tbiAgoDAVZdtZOq7gAIsr Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org There are deadlocks caused by del_timer_sync(&priv->hang_timer) and del_timer_sync(&priv->rr_timer) in grcan_close(), one of the deadlocks are shown below: (Thread 1) | (Thread 2) | grcan_reset_timer() grcan_close() | mod_timer() spin_lock_irqsave() //(1) | (wait a time) ... | grcan_initiate_running_reset() del_timer_sync() | spin_lock_irqsave() //(2) (wait timer to stop) | ... We hold priv->lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need priv->lock in position (2) of thread 2. As a result, grcan_close() will block forever. This patch extracts del_timer_sync() from the protection of spin_lock_irqsave(), which could let timer handler to obtain the needed lock. Signed-off-by: Duoming Zhou --- drivers/net/can/grcan.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/can/grcan.c b/drivers/net/can/grcan.c index d0c5a7a60da..1189057b5d6 100644 --- a/drivers/net/can/grcan.c +++ b/drivers/net/can/grcan.c @@ -1102,8 +1102,10 @@ static int grcan_close(struct net_device *dev) priv->closing = true; if (priv->need_txbug_workaround) { + spin_unlock_irqrestore(&priv->lock, flags); del_timer_sync(&priv->hang_timer); del_timer_sync(&priv->rr_timer); + spin_lock_irqsave(&priv->lock, flags); } netif_stop_queue(dev); grcan_stop_hardware(dev);