coresight/ultrasoc: change smb_drv_data spinlock's type to raw_spinlock_t

In ultrasoc-smb drivers, smb_drv_data->spinlock can be held
during __schedule() by perf_event_task_sched_out()/in().

Since smb__drv_data->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 smb_drv_data->spinlock in ultrasoc-smb drivers,
which can be called by perf_event_task_sched_out()/in(),
from spinlock_t to raw_spinlock_t.

Reviewed-by: James Clark <[email protected]>
Signed-off-by: Yeoreum Yun <[email protected]>
Signed-off-by: Suzuki K Poulose <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: LeviYeoReum

drivers/hwtracing/coresight/ultrasoc-smb.c

@@ -98,7 +98,7 @@ static int smb_open(struct inode *inode, struct file *file)
 	struct smb_drv_data *drvdata = container_of(file->private_data,
 					struct smb_drv_data, miscdev);
 
-	guard(spinlock)(&drvdata->spinlock);
+	guard(raw_spinlock)(&drvdata->spinlock);
 
 	if (drvdata->reading)
 		return -EBUSY;
@@ -152,7 +152,7 @@ static int smb_release(struct inode *inode, struct file *file)
 	struct smb_drv_data *drvdata = container_of(file->private_data,
 					struct smb_drv_data, miscdev);
 
-	guard(spinlock)(&drvdata->spinlock);
+	guard(raw_spinlock)(&drvdata->spinlock);
 	drvdata->reading = false;
 
 	return 0;
@@ -245,7 +245,7 @@ static int smb_enable(struct coresight_device *csdev, enum cs_mode mode,
 	struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
 	int ret = 0;
 
-	guard(spinlock)(&drvdata->spinlock);
+	guard(raw_spinlock)(&drvdata->spinlock);
 
 	/* Do nothing, the trace data is reading by other interface now */
 	if (drvdata->reading)
@@ -280,7 +280,7 @@ static int smb_disable(struct coresight_device *csdev)
 {
 	struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
 
-	guard(spinlock)(&drvdata->spinlock);
+	guard(raw_spinlock)(&drvdata->spinlock);
 
 	if (drvdata->reading)
 		return -EBUSY;
@@ -378,7 +378,7 @@ static unsigned long smb_update_buffer(struct coresight_device *csdev,
 	if (!buf)
 		return 0;
 
-	guard(spinlock)(&drvdata->spinlock);
+	guard(raw_spinlock)(&drvdata->spinlock);
 
 	/* Don't do anything if another tracer is using this sink. */
 	if (csdev->refcnt != 1)
@@ -563,7 +563,7 @@ static int smb_probe(struct platform_device *pdev)
 
 	smb_reset_buffer(drvdata);
 	platform_set_drvdata(pdev, drvdata);
-	spin_lock_init(&drvdata->spinlock);
+	raw_spin_lock_init(&drvdata->spinlock);
 	drvdata->pid = -1;
 
 	ret = smb_register_sink(pdev, drvdata);

drivers/hwtracing/coresight/ultrasoc-smb.h

@@ -115,7 +115,7 @@ struct smb_drv_data {
 	struct coresight_device	*csdev;
 	struct smb_data_buffer sdb;
 	struct miscdevice miscdev;
-	spinlock_t spinlock;
+	raw_spinlock_t spinlock;
 	bool reading;
 	pid_t pid;
 };