cpufreq: stats: Add memory barrier to store_reset()

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There is nothing to prevent the CPU or the compiler from reordering
the writes to stats->reset_time and stats->reset_pending in
store_reset(), in which case the readers of stats->reset_time may see
a stale value.  Moreover, on 32-bit arches the write to reset_time
cannot be completed in one go, so the readers of it may see a
partially updated value in that case.

To prevent that from happening, add a write memory barrier between
the writes to stats->reset_time and stats->reset_pending in
store_reset() and corresponding read memory barrier in the
readers of stats->reset_time.

Fixes: 40c3bd4cfa ("cpufreq: stats: Defer stats update to cpufreq_stats_record_transition()")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

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Rafael J. Wysocki 2020-10-06 21:43:43 +02:00

parent 86836bac55

commit efad4240da

1 changed files with 18 additions and 2 deletions

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drivers/cpufreq/cpufreq_stats.c

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