From mboxrd@z Thu Jan 1 00:00:00 1970 From: alexandre.belloni@free-electrons.com (Alexandre Belloni) Date: Fri, 16 Jan 2015 11:35:30 +0100 Subject: [RFC 2/2] clocksource: don't suspend/resume when unused In-Reply-To: References: <1421399874-29119-1-git-send-email-alexandre.belloni@free-electrons.com> <1421399874-29119-3-git-send-email-alexandre.belloni@free-electrons.com> Message-ID: <20150116103530.GB3843@piout.net> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 16/01/2015 at 11:23:32 +0100, Thomas Gleixner wrote : > On Fri, 16 Jan 2015, Alexandre Belloni wrote: > > > There is no point in calling suspend/resume for unused > > clocksources. > > > > Signed-off-by: Alexandre Belloni > > --- > > kernel/time/clocksource.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c > > index 920a4da58eb0..baea4e42ae90 100644 > > --- a/kernel/time/clocksource.c > > +++ b/kernel/time/clocksource.c > > @@ -493,7 +493,7 @@ void clocksource_suspend(void) > > struct clocksource *cs; > > > > list_for_each_entry_reverse(cs, &clocksource_list, list) > > - if (cs->suspend) > > + if (cs->suspend && (cs->flags & CLOCK_SOURCE_USED)) > > cs->suspend(cs); > > This might be dangerous. If the clocksource has no enable/disable > callbacks, but suspend/resume, then you might leave it enabled across > suspend. > Isn't that already the case? Right now, if you call clocksource_suspend, it doesn't matter whether the clocksource has an enable or not, it will be suspended. Maybe I'm mistaken but my patch doesn't seem to change that behaviour. -- Alexandre Belloni, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753591AbbAPKff (ORCPT ); Fri, 16 Jan 2015 05:35:35 -0500 Received: from down.free-electrons.com ([37.187.137.238]:32993 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751365AbbAPKfc (ORCPT ); Fri, 16 Jan 2015 05:35:32 -0500 Date: Fri, 16 Jan 2015 11:35:30 +0100 From: Alexandre Belloni To: Thomas Gleixner Cc: John Stultz , Daniel Lezcano , Nicolas Ferre , Boris Brezillon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [RFC 2/2] clocksource: don't suspend/resume when unused Message-ID: <20150116103530.GB3843@piout.net> References: <1421399874-29119-1-git-send-email-alexandre.belloni@free-electrons.com> <1421399874-29119-3-git-send-email-alexandre.belloni@free-electrons.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16/01/2015 at 11:23:32 +0100, Thomas Gleixner wrote : > On Fri, 16 Jan 2015, Alexandre Belloni wrote: > > > There is no point in calling suspend/resume for unused > > clocksources. > > > > Signed-off-by: Alexandre Belloni > > --- > > kernel/time/clocksource.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c > > index 920a4da58eb0..baea4e42ae90 100644 > > --- a/kernel/time/clocksource.c > > +++ b/kernel/time/clocksource.c > > @@ -493,7 +493,7 @@ void clocksource_suspend(void) > > struct clocksource *cs; > > > > list_for_each_entry_reverse(cs, &clocksource_list, list) > > - if (cs->suspend) > > + if (cs->suspend && (cs->flags & CLOCK_SOURCE_USED)) > > cs->suspend(cs); > > This might be dangerous. If the clocksource has no enable/disable > callbacks, but suspend/resume, then you might leave it enabled across > suspend. > Isn't that already the case? Right now, if you call clocksource_suspend, it doesn't matter whether the clocksource has an enable or not, it will be suspended. Maybe I'm mistaken but my patch doesn't seem to change that behaviour. -- Alexandre Belloni, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com