From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hilman Subject: Re: [linux-pm] [RFC/PATCH v2] PM / Runtime: allow _put_sync() from interrupts-disabled context Date: Fri, 05 Aug 2011 16:40:19 -0700 Message-ID: <87ipqbo2ak.fsf@ti.com> References: <1311371188-28879-1-git-send-email-khilman@ti.com> <201107240102.09698.rjw@sisk.pl> <87vcuczrey.fsf@ti.com> <201108052122.06949.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from na3sys009aog111.obsmtp.com ([74.125.149.205]:43701 "EHLO na3sys009aog111.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751315Ab1HEXkW (ORCPT ); Fri, 5 Aug 2011 19:40:22 -0400 Received: by mail-iy0-f169.google.com with SMTP id 1so4289351iym.28 for ; Fri, 05 Aug 2011 16:40:21 -0700 (PDT) In-Reply-To: <201108052122.06949.rjw@sisk.pl> (Rafael J. Wysocki's message of "Fri, 5 Aug 2011 21:22:06 +0200") Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: "Rafael J. Wysocki" Cc: linux-pm@lists.linux-foundation.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Alan Stern , Colin Cross "Rafael J. Wysocki" writes: > On Friday, August 05, 2011, Kevin Hilman wrote: >> "Rafael J. Wysocki" writes: >> >> > On Friday, July 22, 2011, Kevin Hilman wrote: >> >> Currently the use of pm_runtime_put_sync() is not safe from >> >> interrupts-disabled context because rpm_idle() will release the >> >> spinlock and enable interrupts for the idle callbacks. This enables >> >> interrupts during a time where interrupts were expected to be >> >> disabled, and can have strange side effects on drivers that expected >> >> interrupts to be disabled. >> >> >> >> This is not a bug since the documentation clearly states that only >> >> _put_sync_suspend() is safe in IRQ-safe mode. >> >> >> >> However, pm_runtime_put_sync() could be made safe when in IRQ-safe >> >> mode by releasing the spinlock but not re-enabling interrupts, which >> >> is what this patch aims to do. >> >> >> >> Problem was found when using some buggy drivers that set >> >> pm_runtime_irq_safe() and used _put_sync() in interrupts-disabled >> >> context. >> >> >> >> The offending drivers have been fixed to use _put_sync_suspend(), >> >> But this patch is an RFC to see if it might make sense to allow >> >> using _put_sync() from interrupts-disabled context. >> > >> > OK, I'm going to take this for 3.2. >> >> Rafael, >> >> Since you're planning to merge this, maybe we should consider merging >> this as a fix for v3.1, and possibly even for v3.0 stable. That way, >> any current drivers using irq_safe and the normal _put_sync() will not >> have this problem. > > I think I can push it for 3.1, but I don't think it's stable material. > OK, fair enough. Kevin