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Code Issues Releases Wiki Activity

cpufreq: intel_pstate: Get rid of unnecessary READ_ONCE() annotations

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Drop two redundant checks involving READ_ONCE() from notify_hwp_interrupt()
and make it check hwp_active without READ_ONCE() which is not necessary,
because that variable is only set once during the early initialization of
the driver.

In order to make that clear, annotate hwp_active with __ro_after_init.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Rafael J. Wysocki 2024-03-28 19:52:06 +01:00
parent 432acb219a
commit 0f2828e17b
1 changed files with 5 additions and 22 deletions
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27
drivers/cpufreq/intel_pstate.c
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@ -292,7 +292,7 @@ struct pstate_funcs {
static struct pstate_funcs pstate_funcs __read_mostly;
static int hwp_active __read_mostly;
static bool hwp_active __ro_after_init;
static int hwp_mode_bdw __read_mostly;
static bool per_cpu_limits __read_mostly;
static bool hwp_boost __read_mostly;
@ -1636,11 +1636,10 @@ static cpumask_t hwp_intr_enable_mask;
void notify_hwp_interrupt(void)
{
unsigned int this_cpu = smp_processor_id();
struct cpudata *cpudata;
unsigned long flags;
u64 value;
if (!READ_ONCE(hwp_active) || !boot_cpu_has(X86_FEATURE_HWP_NOTIFY))
if (!hwp_active || !boot_cpu_has(X86_FEATURE_HWP_NOTIFY))
return;
rdmsrl_safe(MSR_HWP_STATUS, &value);
@ -1652,24 +1651,8 @@ void notify_hwp_interrupt(void)
if (!cpumask_test_cpu(this_cpu, &hwp_intr_enable_mask))
goto ack_intr;
/*
* Currently we never free all_cpu_data. And we can't reach here
* without this allocated. But for safety for future changes, added
* check.
*/
if (unlikely(!READ_ONCE(all_cpu_data)))
goto ack_intr;
/*
* The free is done during cleanup, when cpufreq registry is failed.
* We wouldn't be here if it fails on init or switch status. But for
* future changes, added check.
*/
cpudata = READ_ONCE(all_cpu_data[this_cpu]);
if (unlikely(!cpudata))
goto ack_intr;
schedule_delayed_work(&cpudata->hwp_notify_work, msecs_to_jiffies(10));
schedule_delayed_work(&all_cpu_data[this_cpu]->hwp_notify_work,
msecs_to_jiffies(10));
spin_unlock_irqrestore(&hwp_notify_lock, flags);
@ -3464,7 +3447,7 @@ static int __init intel_pstate_init(void)
* deal with it.
*/
if ((!no_hwp && boot_cpu_has(X86_FEATURE_HWP_EPP)) || hwp_forced) {
WRITE_ONCE(hwp_active, 1);
hwp_active = true;
hwp_mode_bdw = id->driver_data;
intel_pstate.attr = hwp_cpufreq_attrs;
intel_cpufreq.attr = hwp_cpufreq_attrs;