From mboxrd@z Thu Jan 1 00:00:00 1970 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 576F7C433FE for ; Wed, 23 Nov 2022 09:08:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237039AbiKWJIR (ORCPT ); Wed, 23 Nov 2022 04:08:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44744 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237153AbiKWJH7 (ORCPT ); Wed, 23 Nov 2022 04:07:59 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 580081147C for ; Wed, 23 Nov 2022 01:07:54 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E426B61B4D for ; Wed, 23 Nov 2022 09:07:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F046EC433D7; Wed, 23 Nov 2022 09:07:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1669194473; bh=8HKXCGGVFpmxdo+NKF8LQteVHYmNXwRyQa8UNM5udUs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OudIGJ2wre7qhbMTiIGEL12H6ASvPyFRet1lGQoGrnJoAP4haXu2hwgbIhueG09ND MM7TRHLDkSLRNtgU71sVmGlFiUfuXkJjsMUXalzT8zts67yqTKzzfu45tsOPQ3vxd+ 9P9OCv2RYu21f3UOittSFx8UfruvKhYeWmsxPTb8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Duoming Zhou Subject: [PATCH 4.19 088/114] usb: chipidea: fix deadlock in ci_otg_del_timer Date: Wed, 23 Nov 2022 09:51:15 +0100 Message-Id: <20221123084555.350930798@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221123084551.864610302@linuxfoundation.org> References: <20221123084551.864610302@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Duoming Zhou commit 7a58b8d6021426b796eebfae80983374d9a80a75 upstream. There is a deadlock in ci_otg_del_timer(), the process is shown below: (thread 1) | (thread 2) ci_otg_del_timer() | ci_otg_hrtimer_func() ... | spin_lock_irqsave() //(1) | ... ... | hrtimer_cancel() | spin_lock_irqsave() //(2) (block forever) We hold ci->lock in position (1) and use hrtimer_cancel() to wait ci_otg_hrtimer_func() to stop, but ci_otg_hrtimer_func() also need ci->lock in position (2). As a result, the hrtimer_cancel() in ci_otg_del_timer() will be blocked forever. This patch extracts hrtimer_cancel() from the protection of spin_lock_irqsave() in order that the ci_otg_hrtimer_func() could obtain the ci->lock. What`s more, there will be no race happen. Because the "next_timer" is always under the protection of spin_lock_irqsave() and we only check whether "next_timer" equals to NUM_OTG_FSM_TIMERS in the following code. Fixes: 3a316ec4c91c ("usb: chipidea: use hrtimer for otg fsm timers") Cc: stable Signed-off-by: Duoming Zhou Link: https://lore.kernel.org/r/20220918033312.94348-1-duoming@zju.edu.cn Signed-off-by: Greg Kroah-Hartman --- drivers/usb/chipidea/otg_fsm.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/usb/chipidea/otg_fsm.c +++ b/drivers/usb/chipidea/otg_fsm.c @@ -256,8 +256,10 @@ static void ci_otg_del_timer(struct ci_h ci->enabled_otg_timer_bits &= ~(1 << t); if (ci->next_otg_timer == t) { if (ci->enabled_otg_timer_bits == 0) { + spin_unlock_irqrestore(&ci->lock, flags); /* No enabled timers after delete it */ hrtimer_cancel(&ci->otg_fsm_hrtimer); + spin_lock_irqsave(&ci->lock, flags); ci->next_otg_timer = NUM_OTG_FSM_TIMERS; } else { /* Find the next timer */