Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754489Ab1EIOgJ (ORCPT ); Mon, 9 May 2011 10:36:09 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:44295 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754460Ab1EIOgH (ORCPT ); Mon, 9 May 2011 10:36:07 -0400 Date: Mon, 9 May 2011 10:36:03 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: "Rafael J. Wysocki" cc: Linux PM mailing list , , Greg KH , LKML , Grant Likely , Guennadi Liakhovetski Subject: Re: [linux-pm] [PATCH 3/5] PM: Support for system-wide power transitions in generic power domains In-Reply-To: <201105082324.19674.rjw@sisk.pl> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1510 Lines: 47 On Sun, 8 May 2011, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki > > Make generic power domains support system-wide power transitions > (system suspend and hibernation). Add suspend, resume, freeze and > thaw callbacks to be associated with struct generic_power_domain > objects and make pm_genpd_init() use them as appropriate. ... > Index: linux-2.6/drivers/base/power/domain.c > =================================================================== > --- linux-2.6.orig/drivers/base/power/domain.c > +++ linux-2.6/drivers/base/power/domain.c > @@ -273,6 +273,280 @@ static int pm_genpd_runtime_resume(struc > > #endif /* CONFIG_PM_RUNTIME */ > > +#ifdef CONFIG_PM_SLEEP > + > +/** > + * pm_genpd_powered_down - Check if power has been removed from a power domain. > + * @genpd: Power domain to check. > + */ > +static bool pm_genpd_powered_down(struct generic_power_domain *genpd) > +{ > + bool ret; > + > + mutex_lock(&genpd->lock); > + ret = genpd->power_is_off; > + mutex_unlock(&genpd->lock); > + > + return ret; > +} What is the purpose of the mutex? On the face of it, there's nothing to prevent another thread from changing the domain's power state in between the mutex_unlock() call and the return statement. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/