[PATCH] cpufreq: conservative: Drop cached requested_freq

[Viresh Kumar]

A recently reported issue highlighted that the cached requested_freq
is not guaranteed to stay in sync with policy->cur. If the platform
changes the actual CPU frequency after the governor sets one (e.g.
due to platform-specific frequency scaling) and a re-sync occurs
later, policy->cur may diverge from requested_freq.

This can lead to incorrect behavior in the conservative governor.
For example, the governor may assume the CPU is already running at
the maximum frequency and skip further increases even though there
is still headroom.

Avoid this by dropping the cached requested_freq and using
policy->cur directly.

Reported-by: Lifeng Zheng <zhenglifeng1@xxxxxxxxxx>
Link: https://lore.kernel.org/all/20260210115458.3493646-1-zhenglifeng1@xxxxxxxxxx/
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
Lifeng Zheng, can you please give this a try and provide your Tested-by as well
?

 drivers/cpufreq/cpufreq_conservative.c | 16 +---------------
 1 file changed, 1 insertion(+), 15 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index e0e847764511..c69577e4f941 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -14,7 +14,6 @@
 struct cs_policy_dbs_info {
 	struct policy_dbs_info policy_dbs;
 	unsigned int down_skip;
-	unsigned int requested_freq;
 };
 
 static inline struct cs_policy_dbs_info *to_dbs_info(struct policy_dbs_info *policy_dbs)
@@ -59,10 +58,10 @@ static unsigned int cs_dbs_update(struct cpufreq_policy *policy)
 {
 	struct policy_dbs_info *policy_dbs = policy->governor_data;
 	struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
-	unsigned int requested_freq = dbs_info->requested_freq;
 	struct dbs_data *dbs_data = policy_dbs->dbs_data;
 	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 	unsigned int load = dbs_update(policy);
+	unsigned int requested_freq = policy->cur;
 	unsigned int freq_step;
 
 	/*
@@ -72,16 +71,6 @@ static unsigned int cs_dbs_update(struct cpufreq_policy *policy)
 	if (cs_tuners->freq_step == 0)
 		goto out;
 
-	/*
-	 * If requested_freq is out of range, it is likely that the limits
-	 * changed in the meantime, so fall back to current frequency in that
-	 * case.
-	 */
-	if (requested_freq > policy->max || requested_freq < policy->min) {
-		requested_freq = policy->cur;
-		dbs_info->requested_freq = requested_freq;
-	}
-
 	freq_step = get_freq_step(cs_tuners, policy);
 
 	/*
@@ -113,7 +102,6 @@ static unsigned int cs_dbs_update(struct cpufreq_policy *policy)
 
 		__cpufreq_driver_target(policy, requested_freq,
 					CPUFREQ_RELATION_HE);
-		dbs_info->requested_freq = requested_freq;
 		goto out;
 	}
 
@@ -137,7 +125,6 @@ static unsigned int cs_dbs_update(struct cpufreq_policy *policy)
 
 		__cpufreq_driver_target(policy, requested_freq,
 					CPUFREQ_RELATION_LE);
-		dbs_info->requested_freq = requested_freq;
 	}
 
  out:
@@ -310,7 +297,6 @@ static void cs_start(struct cpufreq_policy *policy)
 	struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
 
 	dbs_info->down_skip = 0;
-	dbs_info->requested_freq = policy->cur;
 }
 
 static struct dbs_governor cs_governor = {
-- 
2.31.1.272.g89b43f80a514