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[-next] cpufreq: CPPC: Fix wrong return value in cppc_get_cpu_cost()

Message ID 20241106011238.2407104-1-ruanjinjie@huawei.com
State Accepted
Commit be392aa80f1e5b0b65ccc2a540b9304fefcfe3d8
Headers show
Series [-next] cpufreq: CPPC: Fix wrong return value in cppc_get_cpu_cost() | expand

Commit Message

Jinjie Ruan Nov. 6, 2024, 1:12 a.m. UTC
cppc_get_cpu_cost() return 0 if the policy is NULL. Then in
em_compute_costs(), the later zero check for cost is not valid
as cost is uninitialized. As Quentin pointed out, kernel energy model
core check the return value of get_cost() first, so if the callback
failed it should tell the core. Return -EINVAL to fix it.

Fixes: 1a1374bb8c59 ("cpufreq: CPPC: Fix possible null-ptr-deref for cppc_get_cpu_cost()")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/all/c4765377-7830-44c2-84fa-706b6e304e10@stanley.mountain/
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Suggested-by: Quentin Perret <qperret@google.com>
---
 drivers/cpufreq/cppc_cpufreq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index aa5dd194fc5b..cdc569cf7743 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -475,7 +475,7 @@  static int cppc_get_cpu_cost(struct device *cpu_dev, unsigned long KHz,
 
 	policy = cpufreq_cpu_get_raw(cpu_dev->id);
 	if (!policy)
-		return 0;
+		return -EINVAL;
 
 	cpu_data = policy->driver_data;
 	perf_caps = &cpu_data->perf_caps;