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 A0521C43334 for ; Mon, 13 Jun 2022 10:31:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343653AbiFMKbO (ORCPT ); Mon, 13 Jun 2022 06:31:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59776 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345079AbiFMK32 (ORCPT ); Mon, 13 Jun 2022 06:29:28 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D2BC925E92; Mon, 13 Jun 2022 03:20:37 -0700 (PDT) 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 ams.source.kernel.org (Postfix) with ESMTPS id 49B2DB80E90; Mon, 13 Jun 2022 10:20:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 92F98C34114; Mon, 13 Jun 2022 10:20:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1655115632; bh=hNbRKfVqo+5QFr9vKzpLdRTCK4YVbnY0OIVNBR0p+64=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E1uQ9n/Kn6HOSNrFakzlguR2I0Uh9HyGYUY6tAqXMoCXhC8UdsQhy2BuxXb2vN7/V Y1JriKnnNVGxD2eS5G5cxzurcsRk8o+5kzILfP8//6nOETQjKYCAQ/KlRTvf3lkC3d CBCKaiTUQ5+a8lAvyg+cU+S3qx53kp93/QlbS1Fo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Duoming Zhou , Sasha Levin Subject: [PATCH 4.9 145/167] drivers: usb: host: Fix deadlock in oxu_bus_suspend() Date: Mon, 13 Jun 2022 12:10:19 +0200 Message-Id: <20220613094914.890559354@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220613094840.720778945@linuxfoundation.org> References: <20220613094840.720778945@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Duoming Zhou [ Upstream commit 4d378f2ae58138d4c55684e1d274e7dd94aa6524 ] There is a deadlock in oxu_bus_suspend(), which is shown below: (Thread 1) | (Thread 2) | timer_action() oxu_bus_suspend() | mod_timer() spin_lock_irq() //(1) | (wait a time) ... | oxu_watchdog() del_timer_sync() | spin_lock_irq() //(2) (wait timer to stop) | ... We hold oxu->lock in position (1) of thread 1, and use del_timer_sync() to wait timer to stop, but timer handler also need oxu->lock in position (2) of thread 2. As a result, oxu_bus_suspend() will block forever. This patch extracts del_timer_sync() from the protection of spin_lock_irq(), which could let timer handler to obtain the needed lock. Signed-off-by: Duoming Zhou Link: https://lore.kernel.org/r/20220417120305.64577-1-duoming@zju.edu.cn Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/usb/host/oxu210hp-hcd.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/usb/host/oxu210hp-hcd.c b/drivers/usb/host/oxu210hp-hcd.c index 2f48da0c0bb3..af5248f62c59 100644 --- a/drivers/usb/host/oxu210hp-hcd.c +++ b/drivers/usb/host/oxu210hp-hcd.c @@ -3491,8 +3491,10 @@ static int oxu_bus_suspend(struct usb_hcd *hcd) } } + spin_unlock_irq(&oxu->lock); /* turn off now-idle HC */ del_timer_sync(&oxu->watchdog); + spin_lock_irq(&oxu->lock); ehci_halt(oxu); hcd->state = HC_STATE_SUSPENDED; -- 2.35.1