cpufreq: intel_pstate: Wait for canceled delayed work to complete

Make intel_pstate_disable_hwp_interrupt() wait for canceled delayed work
to complete to avoid leftover work items running when it returns which
may be during driver unregistration and may confuse things going forward.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/intel_pstate.c

@@ -1682,16 +1682,20 @@ void notify_hwp_interrupt(void)
 
 static void intel_pstate_disable_hwp_interrupt(struct cpudata *cpudata)
 {
+	bool cancel_work;
+
 	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_irq(&hwp_notify_lock);
-	if (cpumask_test_and_clear_cpu(cpudata->cpu, &hwp_intr_enable_mask))
-		cancel_delayed_work(&cpudata->hwp_notify_work);
+	cancel_work = cpumask_test_and_clear_cpu(cpudata->cpu, &hwp_intr_enable_mask);
 	spin_unlock_irq(&hwp_notify_lock);
+
+	if (cancel_work)
+		cancel_delayed_work_sync(&cpudata->hwp_notify_work);
 }
 
 static void intel_pstate_enable_hwp_interrupt(struct cpudata *cpudata)