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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 43877C1B0F2 for ; Wed, 20 Jun 2018 09:12:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0744820846 for ; Wed, 20 Jun 2018 09:12:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0744820846 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754801AbeFTJM1 (ORCPT ); Wed, 20 Jun 2018 05:12:27 -0400 Received: from mga09.intel.com ([134.134.136.24]:1546 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754295AbeFTJMW (ORCPT ); Wed, 20 Jun 2018 05:12:22 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 20 Jun 2018 02:12:21 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,246,1526367600"; d="scan'208";a="50437870" Received: from mattu-haswell.fi.intel.com (HELO [10.237.72.164]) ([10.237.72.164]) by orsmga007.jf.intel.com with ESMTP; 20 Jun 2018 02:12:20 -0700 Subject: Re: [BUG] usb: xhci: Two possible sleep-in-atomic-context bugs To: Peter Chen , Jia-Ju Bai , "mathias.nyman@intel.com" , "gregkh@linuxfoundation.org" Cc: "linux-usb@vger.kernel.org" , Linux Kernel Mailing List References: From: Mathias Nyman Message-ID: <8410b5bf-097c-2b53-84ff-221fb4ab03fa@linux.intel.com> Date: Wed, 20 Jun 2018 12:15:00 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 20.06.2018 06:28, Peter Chen wrote: > >> >> The driver may sleep with holding a spinlock. >> The function call paths (from bottom to top) in Linux-4.16.7 are: >> >> [FUNC] schedule >> drivers/base/power/runtime.c, 741: schedule in rpm_resume >> drivers/base/power/runtime.c, 1322: rpm_resume in pm_runtime_forbid >> drivers/usb/host/xhci-hub.c, 647: pm_runtime_forbid in xhci_enter_test_mode >> drivers/usb/host/xhci-hub.c, 632: _raw_spin_lock_irqsave in xhci_enter_test_mode >> >> [FUNC] schedule >> drivers/base/power/runtime.c, 570: schedule in rpm_suspend >> drivers/base/power/runtime.c, 434: rpm_suspend in rpm_idle >> drivers/base/power/runtime.c, 1343: rpm_idle in pm_runtime_allow >> drivers/usb/host/xhci-hub.c, 670: pm_runtime_allow in xhci_exit_test_mode >> drivers/usb/host/xhci-hub.c, 1387: xhci_exit_test_mode in xhci_hub_control >> drivers/usb/host/xhci-hub.c, 1038: _raw_spin_lock_irqsave in xhci_hub_control >> >> These bugs are found by my static analysis tool (DSAC-2) and checked by my code >> review. >> > > I don't think runtime PM API is needed at xhci_hub_control since the controller should > be always active, Mathias, do you agree I delete pm_runtime_forbid and pm_runtime_allow > to fix this issue? > The USB2 test mode is a bit special, it will disable all connected devices, and halt the host. Port should stay in test mode until feature is cleared or host reset. There is a risk runtime suspend will try to suspend the host as no devices seem preset. But I think pm_runtime_get_noresume() and pm_runtime_put_noidle() could be used instad, those should be safe. -Mathias