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cpufreq: userspace: Move is_managed indicator into per-policy structure

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The userspace governor uses the 'cpu' field of cpufreq_policy structure
to track if it is allowed to set the speed of the policy.

However, there is a window where the 'cpu' field is equal to the value
of nr_cpus_id when all affected CPUs of policy are offline, which is an
illegal value to get the per-CPU variable.

To avoid this issue, modify the governor to use a per-policy indicator
to track if the policy is managed.

Signed-off-by: Liao Chang <liaochang1@huawei.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
[ rjw: Changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Liao Chang 2023-09-12 06:10:57 +00:00 committed by Rafael J. Wysocki
parent 285189c573
commit 9ef0ad49cc
1 changed files with 4 additions and 5 deletions
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9
drivers/cpufreq/cpufreq_userspace.c
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@ -15,9 +15,8 @@
#include <linux/mutex.h>
#include <linux/slab.h>
static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
struct userspace_policy {
unsigned int is_managed;
unsigned int setspeed;
struct mutex mutex;
};
@ -37,7 +36,7 @@ static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
mutex_lock(&userspace->mutex);
if (!per_cpu(cpu_is_managed, policy->cpu))
if (!userspace->is_managed)
goto err;
userspace->setspeed = freq;
@ -85,7 +84,7 @@ static int cpufreq_userspace_policy_start(struct cpufreq_policy *policy)
pr_debug("started managing cpu %u\n", policy->cpu);
mutex_lock(&userspace->mutex);
per_cpu(cpu_is_managed, policy->cpu) = 1;
userspace->is_managed = 1;
userspace->setspeed = policy->cur;
mutex_unlock(&userspace->mutex);
return 0;
@ -98,7 +97,7 @@ static void cpufreq_userspace_policy_stop(struct cpufreq_policy *policy)
pr_debug("managing cpu %u stopped\n", policy->cpu);
mutex_lock(&userspace->mutex);
per_cpu(cpu_is_managed, policy->cpu) = 0;
userspace->is_managed = 0;
userspace->setspeed = 0;
mutex_unlock(&userspace->mutex);
}