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 X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BFBACC4332B for ; Mon, 11 Jan 2021 13:04:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8ABFC22A84 for ; Mon, 11 Jan 2021 13:04:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730192AbhAKNEm (ORCPT ); Mon, 11 Jan 2021 08:04:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:50820 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730144AbhAKNEL (ORCPT ); Mon, 11 Jan 2021 08:04:11 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id A0B9722510; Mon, 11 Jan 2021 13:03:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1610370236; bh=jo4RtVvdmWtVgWNCwYhEMwcWPnuklUH9D2hsuT5/PuI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a/V+zoEn9T82vUS/ltJT1NbgQMS2hVzP9eNwlmuPknpxIjW05qTuFD6SV+BXfp8oh 9oqVRJLUEF6Jjh5lOzwZEyTT80PORVVw7TKGf1oxvzQJdWIBrTSh/BIjwfuAlecKaI 00SbaYVd8IAGp62Xrzgw/reRXTuo0VbOoMUUlIUo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Peter Chen , Sriharsha Allenki Subject: [PATCH 4.9 36/45] usb: gadget: Fix spinlock lockup on usb_function_deactivate Date: Mon, 11 Jan 2021 14:01:14 +0100 Message-Id: <20210111130035.385152365@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210111130033.676306636@linuxfoundation.org> References: <20210111130033.676306636@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: Sriharsha Allenki commit 5cc35c224a80aa5a5a539510ef049faf0d6ed181 upstream. There is a spinlock lockup as part of composite_disconnect when it tries to acquire cdev->lock as part of usb_gadget_deactivate. This is because the usb_gadget_deactivate is called from usb_function_deactivate with the same spinlock held. This would result in the below call stack and leads to stall. rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 3-...0: (1 GPs behind) idle=162/1/0x4000000000000000 softirq=10819/10819 fqs=2356 (detected by 2, t=5252 jiffies, g=20129, q=3770) Task dump for CPU 3: task:uvc-gadget_wlhe state:R running task stack: 0 pid: 674 ppid: 636 flags:0x00000202 Call trace: __switch_to+0xc0/0x170 _raw_spin_lock_irqsave+0x84/0xb0 composite_disconnect+0x28/0x78 configfs_composite_disconnect+0x68/0x70 usb_gadget_disconnect+0x10c/0x128 usb_gadget_deactivate+0xd4/0x108 usb_function_deactivate+0x6c/0x80 uvc_function_disconnect+0x20/0x58 uvc_v4l2_release+0x30/0x88 v4l2_release+0xbc/0xf0 __fput+0x7c/0x230 ____fput+0x14/0x20 task_work_run+0x88/0x140 do_notify_resume+0x240/0x6f0 work_pending+0x8/0x200 Fix this by doing an unlock on cdev->lock before the usb_gadget_deactivate call from usb_function_deactivate. The same lockup can happen in the usb_gadget_activate path. Fix that path as well. Reported-by: Peter Chen Link: https://lore.kernel.org/linux-usb/20201102094936.GA29581@b29397-desktop/ Tested-by: Peter Chen Signed-off-by: Sriharsha Allenki Cc: stable Link: https://lore.kernel.org/r/20201202130220.24926-1-sallenki@codeaurora.org Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/composite.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/drivers/usb/gadget/composite.c +++ b/drivers/usb/gadget/composite.c @@ -392,8 +392,11 @@ int usb_function_deactivate(struct usb_f spin_lock_irqsave(&cdev->lock, flags); - if (cdev->deactivations == 0) + if (cdev->deactivations == 0) { + spin_unlock_irqrestore(&cdev->lock, flags); status = usb_gadget_deactivate(cdev->gadget); + spin_lock_irqsave(&cdev->lock, flags); + } if (status == 0) cdev->deactivations++; @@ -424,8 +427,11 @@ int usb_function_activate(struct usb_fun status = -EINVAL; else { cdev->deactivations--; - if (cdev->deactivations == 0) + if (cdev->deactivations == 0) { + spin_unlock_irqrestore(&cdev->lock, flags); status = usb_gadget_activate(cdev->gadget); + spin_lock_irqsave(&cdev->lock, flags); + } } spin_unlock_irqrestore(&cdev->lock, flags);