From mboxrd@z Thu Jan 1 00:00:00 1970 From: Saravana Kannan Subject: Re: [PATCH v3 1/2] cpufreq: Don't destroy/realloc policy/sysfs on hotplug/suspend Date: Thu, 17 Jul 2014 20:25:03 -0700 Message-ID: <53C8938F.1070706@codeaurora.org> References: <1405464473-3916-1-git-send-email-skannan@codeaurora.org> <1405464473-3916-2-git-send-email-skannan@codeaurora.org> <53C65F03.1050609@mit.edu> <53C6D8EC.1030609@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.codeaurora.org ([198.145.11.231]:56267 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759722AbaGRDZG (ORCPT ); Thu, 17 Jul 2014 23:25:06 -0400 In-Reply-To: Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: Viresh Kumar Cc: "Srivatsa S. Bhat" , "Rafael J . Wysocki" , Todd Poynor , "linux-pm@vger.kernel.org" , Linux Kernel Mailing List , "linux-arm-msm@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Stephen Boyd On 07/16/2014 10:35 PM, Viresh Kumar wrote: > On 17 July 2014 01:26, Saravana Kannan wrote: >> On 07/16/2014 04:16 AM, Srivatsa S. Bhat wrote: > >>> That is, we wanted >>> to do the kobject cleanup after releasing the hotplug lock, and POST_DEAD >>> stage was well-suited for that. > > I think, this has changed in Saravana's patch, we do it in the PREPARE stage > now. Not really. We much never do it during hotplug. We only do it when the cpufreq driver unregisters. This should be easier to see in v4, where I'm breaking up the patches into easier diffs. >>> Commit 1aee40ac9c8 (cpufreq: Invoke __cpufreq_remove_dev_finish() after >>> releasing cpu_hotplug.lock) explains this in detail. Saravana, please take >>> a >>> look at that reasoning and ensure that your patch doesn't re-introduce >>> those >>> deadlock possibilities! >> >> >> But all of that was needed _because_ we were creating and destroying >> policies and kobjs all the time. We don't do that anymore. So, I don't think >> any of that applies. We only destroy when the cpufreq driver is >> unregistered. That's kinda of the point of this patchset. >> >> Thoughts? > > See above. > -Saravana -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760026AbaGRDZJ (ORCPT ); Thu, 17 Jul 2014 23:25:09 -0400 Received: from smtp.codeaurora.org ([198.145.11.231]:56267 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759722AbaGRDZG (ORCPT ); Thu, 17 Jul 2014 23:25:06 -0400 Message-ID: <53C8938F.1070706@codeaurora.org> Date: Thu, 17 Jul 2014 20:25:03 -0700 From: Saravana Kannan User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 MIME-Version: 1.0 To: Viresh Kumar CC: "Srivatsa S. Bhat" , "Rafael J . Wysocki" , Todd Poynor , "linux-pm@vger.kernel.org" , Linux Kernel Mailing List , "linux-arm-msm@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Stephen Boyd Subject: Re: [PATCH v3 1/2] cpufreq: Don't destroy/realloc policy/sysfs on hotplug/suspend References: <1405464473-3916-1-git-send-email-skannan@codeaurora.org> <1405464473-3916-2-git-send-email-skannan@codeaurora.org> <53C65F03.1050609@mit.edu> <53C6D8EC.1030609@codeaurora.org> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/16/2014 10:35 PM, Viresh Kumar wrote: > On 17 July 2014 01:26, Saravana Kannan wrote: >> On 07/16/2014 04:16 AM, Srivatsa S. Bhat wrote: > >>> That is, we wanted >>> to do the kobject cleanup after releasing the hotplug lock, and POST_DEAD >>> stage was well-suited for that. > > I think, this has changed in Saravana's patch, we do it in the PREPARE stage > now. Not really. We much never do it during hotplug. We only do it when the cpufreq driver unregisters. This should be easier to see in v4, where I'm breaking up the patches into easier diffs. >>> Commit 1aee40ac9c8 (cpufreq: Invoke __cpufreq_remove_dev_finish() after >>> releasing cpu_hotplug.lock) explains this in detail. Saravana, please take >>> a >>> look at that reasoning and ensure that your patch doesn't re-introduce >>> those >>> deadlock possibilities! >> >> >> But all of that was needed _because_ we were creating and destroying >> policies and kobjs all the time. We don't do that anymore. So, I don't think >> any of that applies. We only destroy when the cpufreq driver is >> unregistered. That's kinda of the point of this patchset. >> >> Thoughts? > > See above. > -Saravana -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation From mboxrd@z Thu Jan 1 00:00:00 1970 From: skannan@codeaurora.org (Saravana Kannan) Date: Thu, 17 Jul 2014 20:25:03 -0700 Subject: [PATCH v3 1/2] cpufreq: Don't destroy/realloc policy/sysfs on hotplug/suspend In-Reply-To: References: <1405464473-3916-1-git-send-email-skannan@codeaurora.org> <1405464473-3916-2-git-send-email-skannan@codeaurora.org> <53C65F03.1050609@mit.edu> <53C6D8EC.1030609@codeaurora.org> Message-ID: <53C8938F.1070706@codeaurora.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 07/16/2014 10:35 PM, Viresh Kumar wrote: > On 17 July 2014 01:26, Saravana Kannan wrote: >> On 07/16/2014 04:16 AM, Srivatsa S. Bhat wrote: > >>> That is, we wanted >>> to do the kobject cleanup after releasing the hotplug lock, and POST_DEAD >>> stage was well-suited for that. > > I think, this has changed in Saravana's patch, we do it in the PREPARE stage > now. Not really. We much never do it during hotplug. We only do it when the cpufreq driver unregisters. This should be easier to see in v4, where I'm breaking up the patches into easier diffs. >>> Commit 1aee40ac9c8 (cpufreq: Invoke __cpufreq_remove_dev_finish() after >>> releasing cpu_hotplug.lock) explains this in detail. Saravana, please take >>> a >>> look at that reasoning and ensure that your patch doesn't re-introduce >>> those >>> deadlock possibilities! >> >> >> But all of that was needed _because_ we were creating and destroying >> policies and kobjs all the time. We don't do that anymore. So, I don't think >> any of that applies. We only destroy when the cpufreq driver is >> unregistered. That's kinda of the point of this patchset. >> >> Thoughts? > > See above. > -Saravana -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation