1 files changed, 41 insertions, 9 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index df445b44e9ec..6682f422cadd 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -534,16 +534,18 @@ void cpufreq_disable_fast_switch(struct cpufreq_policy *policy)
 EXPORT_SYMBOL_GPL(cpufreq_disable_fast_switch);
 
 static unsigned int __resolve_freq(struct cpufreq_policy *policy,
-		unsigned int target_freq, unsigned int relation)
+				   unsigned int target_freq,
+				   unsigned int min, unsigned int max,
+				   unsigned int relation)
 {
 	unsigned int idx;
 
-	target_freq = clamp_val(target_freq, policy->min, policy->max);
+	target_freq = clamp_val(target_freq, min, max);
 
 	if (!policy->freq_table)
 		return target_freq;
 
-	idx = cpufreq_frequency_table_target(policy, target_freq, relation);
+	idx = cpufreq_frequency_table_target(policy, target_freq, min, max, relation);
 	policy->cached_resolved_idx = idx;
 	policy->cached_target_freq = target_freq;
 	return policy->freq_table[idx].frequency;
@@ -563,7 +565,21 @@ static unsigned int __resolve_freq(struct cpufreq_policy *policy,
 unsigned int cpufreq_driver_resolve_freq(struct cpufreq_policy *policy,
 					 unsigned int target_freq)
 {
-	return __resolve_freq(policy, target_freq, CPUFREQ_RELATION_LE);
+	unsigned int min = READ_ONCE(policy->min);
+	unsigned int max = READ_ONCE(policy->max);
+
+	/*
+	 * If this function runs in parallel with cpufreq_set_policy(), it may
+	 * read policy->min before the update and policy->max after the update
+	 * or the other way around, so there is no ordering guarantee.
+	 *
+	 * Resolve this by always honoring the max (in case it comes from
+	 * thermal throttling or similar).
+	 */
+	if (unlikely(min > max))
+		min = max;
+
+	return __resolve_freq(policy, target_freq, min, max, CPUFREQ_RELATION_LE);
 }
 EXPORT_SYMBOL_GPL(cpufreq_driver_resolve_freq);
 
@@ -2335,7 +2351,8 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
 	if (cpufreq_disabled())
 		return -ENODEV;
 
-	target_freq = __resolve_freq(policy, target_freq, relation);
+	target_freq = __resolve_freq(policy, target_freq, policy->min,
+				     policy->max, relation);
 
 	pr_debug("target for CPU %u: %u kHz, relation %u, requested %u kHz\n",
 		 policy->cpu, target_freq, relation, old_target_freq);
@@ -2625,11 +2642,18 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
 	 * Resolve policy min/max to available frequencies. It ensures
 	 * no frequency resolution will neither overshoot the requested maximum
 	 * nor undershoot the requested minimum.
+	 *
+	 * Avoid storing intermediate values in policy->max or policy->min and
+	 * compiler optimizations around them because they may be accessed
+	 * concurrently by cpufreq_driver_resolve_freq() during the update.
 	 */
-	policy->min = new_data.min;
-	policy->max = new_data.max;
-	policy->min = __resolve_freq(policy, policy->min, CPUFREQ_RELATION_L);
-	policy->max = __resolve_freq(policy, policy->max, CPUFREQ_RELATION_H);
+	WRITE_ONCE(policy->max, __resolve_freq(policy, new_data.max,
+					       new_data.min, new_data.max,
+					       CPUFREQ_RELATION_H));
+	new_data.min = __resolve_freq(policy, new_data.min, new_data.min,
+				      new_data.max, CPUFREQ_RELATION_L);
+	WRITE_ONCE(policy->min, new_data.min > policy->max ? policy->max : new_data.min);
+
 	trace_cpu_frequency_limits(policy);
 
 	policy->cached_target_freq = UINT_MAX;
@@ -2725,10 +2749,18 @@ EXPORT_SYMBOL(cpufreq_update_policy);
  */
 void cpufreq_update_limits(unsigned int cpu)
 {
+	struct cpufreq_policy *policy;
+
+	policy = cpufreq_cpu_get(cpu);
+	if (!policy)
+		return;
+
 	if (cpufreq_driver->update_limits)
 		cpufreq_driver->update_limits(cpu);
 	else
 		cpufreq_update_policy(cpu);
+
+	cpufreq_cpu_put(policy);
 }
 EXPORT_SYMBOL_GPL(cpufreq_update_limits);