Commit 0f2828e1 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

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



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: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 432acb21

drivers/cpufreq/intel_pstate.c

+5 −22
Original line number Diff line number Diff line
@@ -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;