coresight-etm4x: change etmv4_drvdata spinlock type to raw_spinlock_t

In coresight-etm4x drivers, etmv4_drvdata->spinlock can be held during
__schedule() by perf_event_task_sched_out()/in().

Since etmv4_drvdata->spinlock type is spinlock_t and
perf_event_task_sched_out()/in() is called after acquiring rq_lock,
which is raw_spinlock_t (an unsleepable lock),
this poses an issue in PREEMPT_RT kernel where spinlock_t is sleepable.

To address this, change type etmv4_drvdata->spinlock
in coresight-etm4x drivers, which can be called
by perf_event_task_sched_out()/in(), from spinlock_t to raw_spinlock_t.

Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250306121110.1647948-3-yeoreum.yun@arm.com

Author: LeviYeoReum

drivers/hwtracing/coresight/coresight-config.c

@@ -76,10 +76,10 @@ static int cscfg_set_on_enable(struct cscfg_feature_csdev *feat_csdev)
 	unsigned long flags;
 	int i;
 
-	spin_lock_irqsave(feat_csdev->drv_spinlock, flags);
+	raw_spin_lock_irqsave(feat_csdev->drv_spinlock, flags);
 	for (i = 0; i < feat_csdev->nr_regs; i++)
 		cscfg_set_reg(&feat_csdev->regs_csdev[i]);
-	spin_unlock_irqrestore(feat_csdev->drv_spinlock, flags);
+	raw_spin_unlock_irqrestore(feat_csdev->drv_spinlock, flags);
 	dev_dbg(&feat_csdev->csdev->dev, "Feature %s: %s",
 		feat_csdev->feat_desc->name, "set on enable");
 	return 0;
@@ -91,10 +91,10 @@ static void cscfg_save_on_disable(struct cscfg_feature_csdev *feat_csdev)
 	unsigned long flags;
 	int i;
 
-	spin_lock_irqsave(feat_csdev->drv_spinlock, flags);
+	raw_spin_lock_irqsave(feat_csdev->drv_spinlock, flags);
 	for (i = 0; i < feat_csdev->nr_regs; i++)
 		cscfg_save_reg(&feat_csdev->regs_csdev[i]);
-	spin_unlock_irqrestore(feat_csdev->drv_spinlock, flags);
+	raw_spin_unlock_irqrestore(feat_csdev->drv_spinlock, flags);
 	dev_dbg(&feat_csdev->csdev->dev, "Feature %s: %s",
 		feat_csdev->feat_desc->name, "save on disable");
 }

drivers/hwtracing/coresight/coresight-config.h

@@ -206,7 +206,7 @@ struct cscfg_feature_csdev {
 	const struct cscfg_feature_desc *feat_desc;
 	struct coresight_device *csdev;
 	struct list_head node;
-	spinlock_t *drv_spinlock;
+	raw_spinlock_t *drv_spinlock;
 	int nr_params;
 	struct cscfg_parameter_csdev *params_csdev;
 	int nr_regs;

drivers/hwtracing/coresight/coresight-etm4x-core.c

@@ -830,7 +830,7 @@ static int etm4_enable_sysfs(struct coresight_device *csdev, struct coresight_pa
 			return ret;
 	}
 
-	spin_lock(&drvdata->spinlock);
+	raw_spin_lock(&drvdata->spinlock);
 
 	drvdata->trcid = path->trace_id;
 
@@ -849,7 +849,7 @@ static int etm4_enable_sysfs(struct coresight_device *csdev, struct coresight_pa
 	if (ret)
 		etm4_release_trace_id(drvdata);
 
-	spin_unlock(&drvdata->spinlock);
+	raw_spin_unlock(&drvdata->spinlock);
 
 	if (!ret)
 		dev_dbg(&csdev->dev, "ETM tracing enabled\n");
@@ -1011,15 +1011,15 @@ static void etm4_disable_sysfs(struct coresight_device *csdev)
 	 * DYING hotplug callback is serviced by the ETM driver.
 	 */
 	cpus_read_lock();
-	spin_lock(&drvdata->spinlock);
+	raw_spin_lock(&drvdata->spinlock);
 
 	/*
 	 * Executing etm4_disable_hw on the cpu whose ETM is being disabled
 	 * ensures that register writes occur when cpu is powered.
 	 */
 	smp_call_function_single(drvdata->cpu, etm4_disable_hw, drvdata, 1);
 
-	spin_unlock(&drvdata->spinlock);
+	raw_spin_unlock(&drvdata->spinlock);
 	cpus_read_unlock();
 
 	/*
@@ -1698,13 +1698,13 @@ static int etm4_starting_cpu(unsigned int cpu)
 	if (!etmdrvdata[cpu])
 		return 0;
 
-	spin_lock(&etmdrvdata[cpu]->spinlock);
+	raw_spin_lock(&etmdrvdata[cpu]->spinlock);
 	if (!etmdrvdata[cpu]->os_unlock)
 		etm4_os_unlock(etmdrvdata[cpu]);
 
 	if (coresight_get_mode(etmdrvdata[cpu]->csdev))
 		etm4_enable_hw(etmdrvdata[cpu]);
-	spin_unlock(&etmdrvdata[cpu]->spinlock);
+	raw_spin_unlock(&etmdrvdata[cpu]->spinlock);
 	return 0;
 }
 
@@ -1713,10 +1713,10 @@ static int etm4_dying_cpu(unsigned int cpu)
 	if (!etmdrvdata[cpu])
 		return 0;
 
-	spin_lock(&etmdrvdata[cpu]->spinlock);
+	raw_spin_lock(&etmdrvdata[cpu]->spinlock);
 	if (coresight_get_mode(etmdrvdata[cpu]->csdev))
 		etm4_disable_hw(etmdrvdata[cpu]);
-	spin_unlock(&etmdrvdata[cpu]->spinlock);
+	raw_spin_unlock(&etmdrvdata[cpu]->spinlock);
 	return 0;
 }
 
@@ -2160,7 +2160,7 @@ static int etm4_probe(struct device *dev)
 			return -ENOMEM;
 	}
 
-	spin_lock_init(&drvdata->spinlock);
+	raw_spin_lock_init(&drvdata->spinlock);
 
 	drvdata->cpu = coresight_get_cpu(dev);
 	if (drvdata->cpu < 0)