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Message-ID: <2807232.mvXUDI8C0e@rafael.j.wysocki>
Date: Fri, 07 Nov 2025 19:18:26 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: [PATCH v1] cpufreq: intel_pstate: Use mutex guard for driver locking
From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Use guard(mutex)(&intel_pstate_driver_lock), or the scoped variant of
it, wherever intel_pstate_driver_lock needs to be held.
This allows some local variables and goto statements to be dropped as
they are not necessary any more.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
drivers/cpufreq/intel_pstate.c | 99 +++++++++++++----------------------------
1 file changed, 33 insertions(+), 66 deletions(-)
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1467,7 +1467,8 @@ static void set_power_ctl_ee_state(bool
{
u64 power_ctl;
- mutex_lock(&intel_pstate_driver_lock);
+ guard(mutex)(&intel_pstate_driver_lock);
+
rdmsrq(MSR_IA32_POWER_CTL, power_ctl);
if (input) {
power_ctl &= ~BIT(MSR_IA32_POWER_CTL_BIT_EE);
@@ -1477,7 +1478,6 @@ static void set_power_ctl_ee_state(bool
power_ctl_ee_state = POWER_CTL_EE_DISABLE;
}
wrmsrq(MSR_IA32_POWER_CTL, power_ctl);
- mutex_unlock(&intel_pstate_driver_lock);
}
static void intel_pstate_hwp_enable(struct cpudata *cpudata);
@@ -1599,13 +1599,9 @@ static int intel_pstate_update_status(co
static ssize_t show_status(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
- ssize_t ret;
-
- mutex_lock(&intel_pstate_driver_lock);
- ret = intel_pstate_show_status(buf);
- mutex_unlock(&intel_pstate_driver_lock);
+ guard(mutex)(&intel_pstate_driver_lock);
- return ret;
+ return intel_pstate_show_status(buf);
}
static ssize_t store_status(struct kobject *a, struct kobj_attribute *b,
@@ -1614,11 +1610,13 @@ static ssize_t store_status(struct kobje
char *p = memchr(buf, '\n', count);
int ret;
- mutex_lock(&intel_pstate_driver_lock);
+ guard(mutex)(&intel_pstate_driver_lock);
+
ret = intel_pstate_update_status(buf, p ? p - buf : count);
- mutex_unlock(&intel_pstate_driver_lock);
+ if (ret < 0)
+ return ret;
- return ret < 0 ? ret : count;
+ return count;
}
static ssize_t show_turbo_pct(struct kobject *kobj,
@@ -1628,12 +1626,10 @@ static ssize_t show_turbo_pct(struct kob
int total, no_turbo, turbo_pct;
uint32_t turbo_fp;
- mutex_lock(&intel_pstate_driver_lock);
+ guard(mutex)(&intel_pstate_driver_lock);
- if (!intel_pstate_driver) {
- mutex_unlock(&intel_pstate_driver_lock);
+ if (!intel_pstate_driver)
return -EAGAIN;
- }
cpu = all_cpu_data[0];
@@ -1642,8 +1638,6 @@ static ssize_t show_turbo_pct(struct kob
turbo_fp = div_fp(no_turbo, total);
turbo_pct = 100 - fp_toint(mul_fp(turbo_fp, int_tofp(100)));
- mutex_unlock(&intel_pstate_driver_lock);
-
return sprintf(buf, "%u\n", turbo_pct);
}
@@ -1653,38 +1647,26 @@ static ssize_t show_num_pstates(struct k
struct cpudata *cpu;
int total;
- mutex_lock(&intel_pstate_driver_lock);
+ guard(mutex)(&intel_pstate_driver_lock);
- if (!intel_pstate_driver) {
- mutex_unlock(&intel_pstate_driver_lock);
+ if (!intel_pstate_driver)
return -EAGAIN;
- }
cpu = all_cpu_data[0];
total = cpu->pstate.turbo_pstate - cpu->pstate.min_pstate + 1;
- mutex_unlock(&intel_pstate_driver_lock);
-
return sprintf(buf, "%u\n", total);
}
static ssize_t show_no_turbo(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
- ssize_t ret;
-
- mutex_lock(&intel_pstate_driver_lock);
+ guard(mutex)(&intel_pstate_driver_lock);
- if (!intel_pstate_driver) {
- mutex_unlock(&intel_pstate_driver_lock);
+ if (!intel_pstate_driver)
return -EAGAIN;
- }
-
- ret = sprintf(buf, "%u\n", global.no_turbo);
-
- mutex_unlock(&intel_pstate_driver_lock);
- return ret;
+ return sprintf(buf, "%u\n", global.no_turbo);
}
static ssize_t store_no_turbo(struct kobject *a, struct kobj_attribute *b,
@@ -1696,29 +1678,25 @@ static ssize_t store_no_turbo(struct kob
if (sscanf(buf, "%u", &input) != 1)
return -EINVAL;
- mutex_lock(&intel_pstate_driver_lock);
+ guard(mutex)(&intel_pstate_driver_lock);
- if (!intel_pstate_driver) {
- count = -EAGAIN;
- goto unlock_driver;
- }
+ if (!intel_pstate_driver)
+ return -EAGAIN;
no_turbo = !!clamp_t(int, input, 0, 1);
WRITE_ONCE(global.turbo_disabled, turbo_is_disabled());
if (global.turbo_disabled && !no_turbo) {
pr_notice("Turbo disabled by BIOS or unavailable on processor\n");
- count = -EPERM;
if (global.no_turbo)
- goto unlock_driver;
- else
- no_turbo = 1;
- }
+ return -EPERM;
- if (no_turbo == global.no_turbo) {
- goto unlock_driver;
+ no_turbo = 1;
}
+ if (no_turbo == global.no_turbo)
+ return count;
+
WRITE_ONCE(global.no_turbo, no_turbo);
mutex_lock(&intel_pstate_limits_lock);
@@ -1737,9 +1715,6 @@ static ssize_t store_no_turbo(struct kob
intel_pstate_update_limits_for_all();
arch_set_max_freq_ratio(no_turbo);
-unlock_driver:
- mutex_unlock(&intel_pstate_driver_lock);
-
return count;
}
@@ -1789,12 +1764,10 @@ static ssize_t store_max_perf_pct(struct
if (ret != 1)
return -EINVAL;
- mutex_lock(&intel_pstate_driver_lock);
+ guard(mutex)(&intel_pstate_driver_lock);
- if (!intel_pstate_driver) {
- mutex_unlock(&intel_pstate_driver_lock);
+ if (!intel_pstate_driver)
return -EAGAIN;
- }
mutex_lock(&intel_pstate_limits_lock);
@@ -1807,8 +1780,6 @@ static ssize_t store_max_perf_pct(struct
else
update_qos_requests(FREQ_QOS_MAX);
- mutex_unlock(&intel_pstate_driver_lock);
-
return count;
}
@@ -1822,12 +1793,10 @@ static ssize_t store_min_perf_pct(struct
if (ret != 1)
return -EINVAL;
- mutex_lock(&intel_pstate_driver_lock);
+ guard(mutex)(&intel_pstate_driver_lock);
- if (!intel_pstate_driver) {
- mutex_unlock(&intel_pstate_driver_lock);
+ if (!intel_pstate_driver)
return -EAGAIN;
- }
mutex_lock(&intel_pstate_limits_lock);
@@ -1841,8 +1810,6 @@ static ssize_t store_min_perf_pct(struct
else
update_qos_requests(FREQ_QOS_MIN);
- mutex_unlock(&intel_pstate_driver_lock);
-
return count;
}
@@ -1863,10 +1830,10 @@ static ssize_t store_hwp_dynamic_boost(s
if (ret)
return ret;
- mutex_lock(&intel_pstate_driver_lock);
+ guard(mutex)(&intel_pstate_driver_lock);
+
hwp_boost = !!input;
intel_pstate_update_policies();
- mutex_unlock(&intel_pstate_driver_lock);
return count;
}
@@ -3977,9 +3944,9 @@ hwp_cpu_matched:
}
- mutex_lock(&intel_pstate_driver_lock);
- rc = intel_pstate_register_driver(default_driver);
- mutex_unlock(&intel_pstate_driver_lock);
+ scoped_guard(mutex, &intel_pstate_driver_lock) {
+ rc = intel_pstate_register_driver(default_driver);
+ }
if (rc) {
intel_pstate_sysfs_remove();
return rc;
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