cpufreq: msm: fix race in cpufreq.
__cpufreq_driver_target expects to be called with the rw semaphore
held. We are not doing this when the frequency is asked to be changed
by dcvs.
Use cpufreq_driver_target variant of that function which gets the
rw semaphore before setting the frequency.
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
(cherry picked from commit 54fc08ea6d33c6c561167f369cba060fe33755c9)
Signed-off-by: Ram Kumar Chakravarthy Chebathini <rcheba@codeaurora.org>
(cherry picked from commit a63446bcd75909db632ffc8ff3c4e6a96c8593c5)
Change-Id: I33cdac0aaac7fb44acf6f9eb451a80ff94175c46
Signed-off-by: Sudhir Sharma <sudsha@codeaurora.org>
diff --git a/drivers/cpufreq/cpufreq_gov_msm.c b/drivers/cpufreq/cpufreq_gov_msm.c
index 616d63c..11eb9f5 100644
--- a/drivers/cpufreq/cpufreq_gov_msm.c
+++ b/drivers/cpufreq/cpufreq_gov_msm.c
@@ -66,13 +66,17 @@
if (freq > gov->max_freq)
freq = gov->max_freq;
- ret = __cpufreq_driver_target(gov->policy, freq, CPUFREQ_RELATION_L);
- gov->cur_freq = gov->policy->cur;
-
mutex_unlock(&per_cpu(gov_mutex, gov->cpu));
- if (!ret)
- return gov->cur_freq;
+ ret = cpufreq_driver_target(gov->policy, freq, CPUFREQ_RELATION_L);
+
+ if (!ret) {
+ gov->cur_freq = cpufreq_quick_get(gov->cpu);
+ if (freq != gov->cur_freq)
+ pr_err("cpu %d freq %u gov->cur_freq %u didn't match",
+ gov->cpu, freq, gov->cur_freq);
+ }
+ ret = gov->cur_freq;
return ret;
}
@@ -82,6 +86,11 @@
struct msm_gov *gov =
container_of(self, struct msm_gov, gov_notifier);
+ /*
+ * the rw_sem in cpufreq is always held when this is called.
+ * The policy->cur won't be updated in this case - so it is safe to
+ * access policy->cur
+ */
return gov->cur_freq;
}