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Date: Tue, 11 Nov 2014 09:10:13 +0530 From: Viresh Kumar <viresh.kumar@...aro.org> To: Prarit Bhargava <prarit@...hat.com> Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Robert Schöne <robert.schoene@...dresden.de>, Stephen Boyd <sboyd@...eaurora.org>, "Rafael J. Wysocki" <rjw@...ysocki.net>, "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org> Subject: Re: [PATCH 3/5] cpufreq, dbs_data->usage count must be atomic On 5 November 2014 20:23, Prarit Bhargava <prarit@...hat.com> wrote: > The usage_count value can be modified from several cpus concurrently if > !CPUFREQ_HAVE_GOVERNOR_PER_POLICY. This leads to a variety of panics in > which the usage_count is negative or exceeds the number of cpus in the > system. It must be switched to atomic_t and protected with a mutex to make sure > that future read/writes obtain the correct data. I think it would be best to serialize calls to ->governor() with some locking in place instead of adding per-variable locks. There can be other points of contention as well. I have done something similar in the solution I tried. Can pick some of those patches. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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