[PATCH] cpufreq: intel_pstate: Make hwp_notify_lock a raw spinlock

["Uwe Kleine-König" <ukleinek@debian.org>]

notify_hwp_interrupt() is called via sysvec_thermal() ->
smp_thermal_vector() -> intel_thermal_interrupt() in hard irq context.
For this reason it must not use a simple spin_lock that sleeps with
PREEMPT_RT enabled. So convert it to a raw spinlock.

Reported-by: xiao sheng wen <atzlinux@sina.com>
Link: https://bugs.debian.org/1076483
Signed-off-by: Uwe Kleine-König <ukleinek@debian.org>
---
Hello,

this is deep in x86 land where I have *very* little experience and
knowledge. Is sysvec_thermal() (defined in arch/x86/kernel/irq.c) really
running in hard irq context? The stacktrace in the Debian bug report
suggests that.

So please double check my reasoning before applying this patch.

Thanks
Uwe

 drivers/cpufreq/intel_pstate.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index aaea9a39eced..b0018f371ea3 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -1845,7 +1845,7 @@ static void intel_pstate_notify_work(struct work_struct *work)
 	wrmsrl_on_cpu(cpudata->cpu, MSR_HWP_STATUS, 0);
 }
 
-static DEFINE_SPINLOCK(hwp_notify_lock);
+static DEFINE_RAW_SPINLOCK(hwp_notify_lock);
 static cpumask_t hwp_intr_enable_mask;
 
 #define HWP_GUARANTEED_PERF_CHANGE_STATUS      BIT(0)
@@ -1868,7 +1868,7 @@ void notify_hwp_interrupt(void)
 	if (!(value & status_mask))
 		return;
 
-	spin_lock_irqsave(&hwp_notify_lock, flags);
+	raw_spin_lock_irqsave(&hwp_notify_lock, flags);
 
 	if (!cpumask_test_cpu(this_cpu, &hwp_intr_enable_mask))
 		goto ack_intr;
@@ -1876,13 +1876,13 @@ void notify_hwp_interrupt(void)
 	schedule_delayed_work(&all_cpu_data[this_cpu]->hwp_notify_work,
 			      msecs_to_jiffies(10));
 
-	spin_unlock_irqrestore(&hwp_notify_lock, flags);
+	raw_spin_unlock_irqrestore(&hwp_notify_lock, flags);
 
 	return;
 
 ack_intr:
 	wrmsrl_safe(MSR_HWP_STATUS, 0);
-	spin_unlock_irqrestore(&hwp_notify_lock, flags);
+	raw_spin_unlock_irqrestore(&hwp_notify_lock, flags);
 }
 
 static void intel_pstate_disable_hwp_interrupt(struct cpudata *cpudata)
@@ -1895,9 +1895,9 @@ static void intel_pstate_disable_hwp_interrupt(struct cpudata *cpudata)
 	/* 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);
+	raw_spin_lock_irq(&hwp_notify_lock);
 	cancel_work = cpumask_test_and_clear_cpu(cpudata->cpu, &hwp_intr_enable_mask);
-	spin_unlock_irq(&hwp_notify_lock);
+	raw_spin_unlock_irq(&hwp_notify_lock);
 
 	if (cancel_work)
 		cancel_delayed_work_sync(&cpudata->hwp_notify_work);
@@ -1912,10 +1912,10 @@ static void intel_pstate_enable_hwp_interrupt(struct cpudata *cpudata)
 	if (boot_cpu_has(X86_FEATURE_HWP_NOTIFY)) {
 		u64 interrupt_mask = HWP_GUARANTEED_PERF_CHANGE_REQ;
 
-		spin_lock_irq(&hwp_notify_lock);
+		raw_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_irq(&hwp_notify_lock);
+		raw_spin_unlock_irq(&hwp_notify_lock);
 
 		if (cpu_feature_enabled(X86_FEATURE_HWP_HIGHEST_PERF_CHANGE))
 			interrupt_mask |= HWP_HIGHEST_PERF_CHANGE_REQ;

base-commit: 3621a2c9142bd490af0666c0c02d52d60ce0d2a5
-- 
2.45.2