From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Stephen Boyd <sboyd@codeaurora.org>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
cpufreq@vger.kernel.org, linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] cpufreq: serialize calls to __cpufreq_governor()
Date: Thu, 05 Sep 2013 02:26:10 +0200 [thread overview]
Message-ID: <16630296.tCCMEKstkO@vostro.rjw.lan> (raw)
In-Reply-To: <5227C729.5040803@codeaurora.org>
On Wednesday, September 04, 2013 04:50:01 PM Stephen Boyd wrote:
> On 09/04/13 16:55, Rafael J. Wysocki wrote:
> >
> > Well, I'm not sure when Viresh is going to be back.
> >
> > Srivatsa, can you please resend this patch with a proper changelog?
> >
>
> I haven't had a chance to try this out yet, but I was just thinking
> about this patch. How is it going to work? If one task opens the file
> and another task is taking down the CPU wouldn't we deadlock in the
> CPU_DOWN notifier waiting for the kobject to be released? Task 1 will
> grab the kobject reference and sleep on the hotplug mutex and task 2
> will put the kobject and wait for the completion, but it won't happen.
> At least I think that's what would happen.
Do you mean the completion in sysfs_deactivate()? Yes, we can deadlock
there.
Well, I guess the Srivatsa's patch may be salvaged by making it do a "trylock"
version of get_online_cpus(), but then I wonder if there's no better way.
Thanks,
Rafael
next prev parent reply other threads:[~2013-09-05 0:15 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-01 5:26 [PATCH 1/2] cpufreq: don't allow governor limits to be changed when it is disabled Viresh Kumar
2013-09-01 5:26 ` [PATCH 2/2] cpufreq: serialize calls to __cpufreq_governor() Viresh Kumar
2013-09-01 13:28 ` Rafael J. Wysocki
2013-09-01 16:00 ` Viresh Kumar
2013-09-01 20:27 ` Rafael J. Wysocki
2013-09-02 1:00 ` Viresh Kumar
2013-09-02 12:44 ` Rafael J. Wysocki
2013-09-03 13:20 ` Srivatsa S. Bhat
2013-09-03 19:40 ` Rafael J. Wysocki
2013-09-13 11:44 ` Viresh Kumar
2013-09-13 23:48 ` Rafael J. Wysocki
2013-09-14 4:29 ` Viresh Kumar
2013-09-17 11:49 ` Srivatsa S. Bhat
2013-09-04 23:55 ` Rafael J. Wysocki
2013-09-04 23:50 ` Stephen Boyd
2013-09-05 0:26 ` Rafael J. Wysocki [this message]
2013-09-05 0:54 ` Stephen Boyd
2013-09-06 6:03 ` Srivatsa S. Bhat
2013-09-06 12:31 ` Rafael J. Wysocki
2013-09-10 6:52 ` Viresh Kumar
2013-09-10 8:47 ` Srivatsa S. Bhat
2013-09-01 6:26 ` [PATCH 1/2] cpufreq: don't allow governor limits to be changed when it is disabled Viresh Kumar
2013-09-01 13:29 ` Rafael J. Wysocki
2013-09-01 13:26 ` Rafael J. Wysocki
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