[2/3] cpufreq: intel_pstate: Use locking in intel_cpufreq_verify_policy()

Commit Message

Rafael J. Wysocki Dec. 30, 2016, 2:57 p.m. UTC

From: Rafael J. Wysocki <[e-mail]>

Race conditions are possible if intel_cpufreq_verify_policy()
is executed in parallel with global limits updates from sysfs,
so the invocation of intel_pstate_update_perf_limits() in it
should be carried out under intel_pstate_limits_lock.

Make that happen.

Signed-off-by: Rafael J. Wysocki <[e-mail]>
---
 drivers/cpufreq/intel_pstate.c |    4 ++++
 1 file changed, 4 insertions(+)


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Patch

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -2157,8 +2157,12 @@  static int intel_cpufreq_verify_policy(s
 	if (per_cpu_limits)
 		perf_limits = cpu->perf_limits;
 
+	mutex_lock(&intel_pstate_limits_lock);
+
 	intel_pstate_update_perf_limits(policy, perf_limits);
 
+	mutex_unlock(&intel_pstate_limits_lock);
+
 	return 0;
 }