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=-18.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_RED autolearn=ham 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 0AF01C4332B for ; Mon, 28 Dec 2020 14:45:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D1799207B2 for ; Mon, 28 Dec 2020 14:45:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2506456AbgL1Op1 (ORCPT ); Mon, 28 Dec 2020 09:45:27 -0500 Received: from mail.kernel.org ([198.145.29.99]:48092 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2506447AbgL1Op0 (ORCPT ); Mon, 28 Dec 2020 09:45:26 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id A8214207CF; Mon, 28 Dec 2020 14:44:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1609166685; bh=8r8pfW3kW1OAGDdCmSeyKwa37PHvNQoO4Jzf+T1Dx8o=; h=Subject:To:From:Date:From; b=01La07FLV49xWK5q4eJT2TwOgi7syXmljHo9RDbMUxvNNZvjuIoCF/p2GkwsOsopR daari8xNgByjqtCt0RWrCotMZttJWKelZjMV4WwYPPsX5lSBm+O/zdj9qnrC6NNdMM yL6qtuouOH+Sp3xK992X3Kk8rcEbs0crK+aqhkgA= Subject: patch "usb: gadget: Fix spinlock lockup on usb_function_deactivate" added to usb-linus To: sallenki@codeaurora.org, gregkh@linuxfoundation.org, peter.chen@nxp.com, stable@vger.kernel.org From: Date: Mon, 28 Dec 2020 15:46:03 +0100 Message-ID: <160916676346169@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled usb: gadget: Fix spinlock lockup on usb_function_deactivate to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will hopefully also be merged in Linus's tree for the next -rc kernel release. If you have any questions about this process, please let me know. >From 5cc35c224a80aa5a5a539510ef049faf0d6ed181 Mon Sep 17 00:00:00 2001 From: Sriharsha Allenki Date: Wed, 2 Dec 2020 18:32:20 +0530 Subject: usb: gadget: Fix spinlock lockup on usb_function_deactivate 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(-) diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c index c6d455f2bb92..1a556a628971 100644 --- a/drivers/usb/gadget/composite.c +++ b/drivers/usb/gadget/composite.c @@ -392,8 +392,11 @@ int usb_function_deactivate(struct usb_function *function) 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_function *function) 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); -- 2.29.2