On 02-06-15, 11:33, Preeti U Murthy wrote:
> No, dbs_data is a governor wide data structure and not a policy wide
Yeah, that's the common part which I was referring to. But normally
its just read for policies in START/STOP, they just update per-cpu
data for policy->cpus.
> one, which is manipulated in START/STOP calls for drivers where the
> CPUFREQ_HAVE_GOVERNOR_PER_POLICY is not set.
>
> So even if we assume that we hold per-policy locks, the following race
> is still present. Assume that we have just two cpus which do not have a
> governor-per-policy set.
>
> CPU0 CPU1
>
> store* store*
>
> lock(policy 1) lock(policy 2)
> cpufreq_set_policy() cpufreq_set_policy()
> EXIT() :
> dbs-data->usage_count--
>
> INIT()
> dbs_data exists
You missed the usage_count++ here.
> so return
> EXIT()
> dbs_data->usage_count -- = 0
> kfree(dbs_data)
And so this shouldn't happen. Else we
are missing locking in governor's
code, rather than cpufreq.c
--
viresh
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