[PATCH v1 2/5] cpufreq: intel_pstate: Simplify spinlock locking

Rafael J. Wysocki
2024-03-21T19:34:24Z

Because intel_pstate_enable/disable_hwp_interrupt() are only called from
thread context, they need not save the IRQ flags when using a spinlock
as interrupts are guaranteed to be enabled when they run, so make them
use spin_lock/unlock_irq().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/cpufreq/intel_pstate.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -1682,30 +1682,26 @@ ack_intr:

static void intel_pstate_disable_hwp_interrupt(struct cpudata *cpudata)
{
- unsigned long flags;
-
if (!boot_cpu_has(X86_FEATURE_HWP_NOTIFY))
return;

/* wrmsrl_on_cpu has to be outside spinlock as this can result in IPC */
wrmsrl_on_cpu(cpudata->cpu, MSR_HWP_INTERRUPT, 0x00);

- spin_lock_irqsave(&hwp_notify_lock, flags);
+ spin_lock_irq(&hwp_notify_lock);
if (cpumask_test_and_clear_cpu(cpudata->cpu, &hwp_intr_enable_mask))
cancel_delayed_work(&cpudata->hwp_notify_work);
- spin_unlock_irqrestore(&hwp_notify_lock, flags);
+ spin_unlock_irq(&hwp_notify_lock);
}

static void intel_pstate_enable_hwp_interrupt(struct cpudata *cpudata)
{
/* Enable HWP notification interrupt for guaranteed performance change */
if (boot_cpu_has(X86_FEATURE_HWP_NOTIFY)) {
- unsigned long flags;
-
- spin_lock_irqsave(&hwp_notify_lock, flags);
+ spin_lock_irq(&hwp_notify_lock);
INIT_DELAYED_WORK(&cpudata->hwp_notify_work, intel_pstate_notify_work);
cpumask_set_cpu(cpudata->cpu, &hwp_intr_enable_mask);
- spin_unlock_irqrestore(&hwp_notify_lock, flags);
+ spin_unlock_irq(&hwp_notify_lock);

/* wrmsrl_on_cpu has to be outside spinlock as this can result in IPC */
wrmsrl_on_cpu(cpudata->cpu, MSR_HWP_INTERRUPT, 0x01);