From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shuah Khan Subject: Re: [PATCH] power: Change device_wakeup_enable() to check for null dev_name(dev) Date: Mon, 18 Nov 2013 10:45:23 -0700 Message-ID: <528A5233.4040306@samsung.com> References: <1384560238-10708-1-git-send-email-shuah.kh@samsung.com> <4035469.UfR6Rto3I2@vostro.rjw.lan> <5286B95F.4040306@samsung.com> <3366600.jMpqPVojcG@vostro.rjw.lan> Reply-To: shuah.kh@samsung.com Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mailout3.w2.samsung.com ([211.189.100.13]:32582 "EHLO usmailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751297Ab3KRRpd (ORCPT ); Mon, 18 Nov 2013 12:45:33 -0500 In-reply-to: <3366600.jMpqPVojcG@vostro.rjw.lan> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: "Rafael J. Wysocki" , anton@enomsg.org, dwmw2@infradead.org Cc: len.brown@intel.com, pavel@ucw.cz, gregkh@linuxfoundation.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, shuahkhan@gmail.com, stable@vger.kernel.org, Shuah Khan On 11/15/2013 05:32 PM, Rafael J. Wysocki wrote: > On Friday, November 15, 2013 05:16:31 PM Shuah Khan wrote: >> On 11/15/2013 05:21 PM, Rafael J. Wysocki wrote: >>> On Friday, November 15, 2013 05:03:57 PM Shuah Khan wrote: >>>> device_wakeup_enable() uses dev_name(dev) as the wakeup source name. >>>> When it gets called with a device with its name not yet set, ws structure >>>> with ws->name = NULL gets created. >>>> >>>> When kernel is booted with wakeup_source_activate enabled, it will panic >>>> when the trace point code tries to derefernces ws->name. >>>> >>>> Change device_wakeup_enable() to check for dev_name(dev) null condition >>>> and return -EINVAL to avoid panics when device_wakeup_enable() gets called >>>> before device is fully initialized with its name. >> return -EINVAL; >>> >>> Can you please use WARN_ON(!dev_name(dev)) here? While I agree that it is a >>> bad idea to crash the kernel because dev has no name, that indicates a driver >>> bug that shouldn't be too easy to ignore. >>> >>> Thanks! >>> >> >> Right. ok I will re-cut the patch with WARN_ON and send it. fyi I did >> send fix for the driver (power_supply) as well. >> >> http://www.kernelhub.org/?msg=362354&p=2 > > That's OK (thanks for taking care of this), but there may be more brilliant > stuff like that in the future and people should see right away that something's > wrong in those cases. > Rafael/Anton/David, I added WARN_ON and testing the patch. We have two instance of device_wakeup_enable() calls with null dev_name during boot. Both are from power_supply_register(). One when AC Adapter [ADP1] is added and the second when device: 'BAT1' gets added. [ 4.412959] device_wakeup_enable() called with null device nme [ 4.412967] device: 'ADP1': device_add [ 4.460190] device_wakeup_enable() called with null device nme [ 4.460197] device: 'BAT1': device_add I think adding WARN_ON to device_wakeup_enable() and fix to power_supply_register() should go in as a dependent patch series, to avoid panics during boot. As soon as the device_wakeup_enable() WARN_ON goes in, I suspect most laptops will panic during boot, similar to what I am seeing in my testing. Thoughts? I will send these fixes, maybe these two can be funneled through PM tree with power_supply maintainers ACK for the power_supply_register() fix. thanks, -- Shuah -- Shuah Khan Senior Linux Kernel Developer - Open Source Group Samsung Research America(Silicon Valley) shuah.kh@samsung.com | (970) 672-0658