From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751823AbdFIQQ5 (ORCPT ); Fri, 9 Jun 2017 12:16:57 -0400 Received: from mail-wr0-f193.google.com ([209.85.128.193]:34219 "EHLO mail-wr0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751803AbdFIQQx (ORCPT ); Fri, 9 Jun 2017 12:16:53 -0400 Date: Fri, 9 Jun 2017 18:16:49 +0200 From: Krzysztof Kozlowski To: "Rafael J. Wysocki" , Kevin Hilman , Ulf Hansson , Pavel Machek , Len Brown , Greg Kroah-Hartman , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/8] PM / domains: Protect reading loop over list of domains Message-ID: <20170609161649.g5wjn24tm2opyq3h@kozik-lap> References: <20170609160853.31789-1-krzk@kernel.org> <20170609160853.31789-3-krzk@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170609160853.31789-3-krzk@kernel.org> User-Agent: Mutt/1.6.2-neo (2016-08-21) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 09, 2017 at 06:08:47PM +0200, Krzysztof Kozlowski wrote: > The pm_genpd_present() iterates over list of domains so grabbing a > gpd_list_lock mutex is necessary before calling it. Otherwise we could > end up in iterating over and modifying the list at the same time. > > Signed-off-by: Krzysztof Kozlowski > --- > drivers/base/power/domain.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c > index 2e8d0f423507..2a6935dc0164 100644 > --- a/drivers/base/power/domain.c > +++ b/drivers/base/power/domain.c > @@ -1099,8 +1099,13 @@ static void genpd_syscore_switch(struct device *dev, bool suspend) > struct generic_pm_domain *genpd; > > genpd = dev_to_genpd(dev); > - if (!pm_genpd_present(genpd)) > + > + mutex_lock(&gpd_list_lock); > + if (!pm_genpd_present(genpd)) { > + mutex_unlock(&gpd_list_lock); > return; > + } > + mutex_unlock(&gpd_list_lock); Eh, I might be too fast as this is not executed on my platform. The genpd_syscore_switch() seems to be called by clocksource_suspend() which is called by syscore ops. Should be safe but actually not tested. Someone with SH hardware is needed... Best regards, Krzysztof