Re: [PATCH 3/5] cpufreq, dbs_data->usage count must be atomic

[Viresh Kumar]

On 5 November 2014 20:23, Prarit Bhargava <prarit@xxxxxxxxxx> 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.
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