From patchwork Fri Apr 29 12:56:09 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Kleine-Budde X-Patchwork-Id: 567725 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 00121C4321E for ; Fri, 29 Apr 2022 12:56:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1359595AbiD2M7j (ORCPT ); Fri, 29 Apr 2022 08:59:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34138 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1359596AbiD2M7h (ORCPT ); Fri, 29 Apr 2022 08:59:37 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A2FD8596D for ; Fri, 29 Apr 2022 05:56:19 -0700 (PDT) Received: from gallifrey.ext.pengutronix.de ([2001:67c:670:201:5054:ff:fe8d:eefb] helo=bjornoya.blackshift.org) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1nkQAT-00008y-IV for stable@vger.kernel.org; Fri, 29 Apr 2022 14:56:17 +0200 Received: from dspam.blackshift.org (localhost [127.0.0.1]) by bjornoya.blackshift.org (Postfix) with SMTP id 2099A70F02 for ; Fri, 29 Apr 2022 12:56:14 +0000 (UTC) Received: from hardanger.blackshift.org (unknown [172.20.34.65]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by bjornoya.blackshift.org (Postfix) with ESMTPS id B965B70EDF; Fri, 29 Apr 2022 12:56:13 +0000 (UTC) Received: from blackshift.org (localhost [::1]) by hardanger.blackshift.org (OpenSMTPD) with ESMTP id d133cfb9; Fri, 29 Apr 2022 12:56:13 +0000 (UTC) From: Marc Kleine-Budde To: netdev@vger.kernel.org Cc: davem@davemloft.net, kuba@kernel.org, linux-can@vger.kernel.org, kernel@pengutronix.de, Duoming Zhou , stable@vger.kernel.org, Andreas Larsson , Marc Kleine-Budde Subject: [PATCH net 2/5] can: grcan: grcan_close(): fix deadlock Date: Fri, 29 Apr 2022 14:56:09 +0200 Message-Id: <20220429125612.1792561-3-mkl@pengutronix.de> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220429125612.1792561-1-mkl@pengutronix.de> References: <20220429125612.1792561-1-mkl@pengutronix.de> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:201:5054:ff:fe8d:eefb X-SA-Exim-Mail-From: mkl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: stable@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Duoming Zhou 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. Link: https://lore.kernel.org/all/20220425042400.66517-1-duoming@zju.edu.cn Fixes: 6cec9b07fe6a ("can: grcan: Add device driver for GRCAN and GRHCAN cores") Cc: stable@vger.kernel.org Signed-off-by: Duoming Zhou Reviewed-by: Andreas Larsson Signed-off-by: Marc Kleine-Budde --- 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 d0c5a7a60daf..1189057b5d68 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);