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Date: Thu, 23 Jun 2016 18:07:58 +0530 From: Keerthy <a0393675@...com> To: "Rafael J. Wysocki" <rafael@...nel.org>, Eduardo Valentin <edubezval@...il.com> CC: Rui Zhang <rui.zhang@...el.com>, "Rafael J. Wysocki" <rjw@...ysocki.net>, Len Brown <lenb@...nel.org>, ACPI Devel Maling List <linux-acpi@...r.kernel.org>, "Lee, Chun-Yi" <jlee@...e.com>, Darren Hart <dvhart@...radead.org>, Keerthy <j-keerthy@...com>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Linux OMAP Mailing List <linux-omap@...r.kernel.org>, <platform-driver-x86@...r.kernel.org>, "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org> Subject: Re: [PATCH 1/1] thermal: core: call thermal_zone_device_update() after mode update On Thursday 23 June 2016 05:57 PM, Rafael J. Wysocki wrote: > On Wed, Jun 22, 2016 at 7:06 AM, Eduardo Valentin <edubezval@...il.com> wrote: >> Because several drivers do the following pattern: >> .set_mode() >> ... >> local_data->mode = new_mode; >> thermal_zone_device_update(tz); >> >> makes sense to simply do the thermal_zone_device_update() >> in thermal core, after setting the new mode. >> >> Also, this patch also remove deadlocks on drivers that >> call thermal_zone_device_update() on .set_mode(), >> as .set_mode() is now called always with tz->lock held. > > To me, this part of the patch is way more important than the > optimization mentioned before. > > Apparently, the problem is that drivers deadlock, because the > thermal_zone_device_update() invoked from ->set_mode() is called under > tz->lock. > > So to address that problem you make the core call > thermal_zone_device_update() after ->set_mode() outside of tz->lock > and the drivers don't have to do it any more. > > Is that correct? Rafael, On my set up, mode_store locks tz->lock and eventually ends up calling of_thermal_set_mode before releasing tz->lock which again tries to lock tz->lock and ends up in a deadlock. http://pastebin.ubuntu.com/17687601/ Regards, Keerthy > > Thanks, > Rafael >
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