coresight-etb10: change etb_drvdata spinlock's type to raw_spinlock_t

In coresight-etb10 drivers, etb_drvdata->spinlock can be held
during __schedule() by perf_event_task_sched_out()/in().

Since etb_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 etb_drvdata->spinlock in coresight-etb10 drivers,
which can be called by perf_event_task_sched_out()/in(),
from spinlock_t to raw_spinlock_t.

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

drivers/hwtracing/coresight/coresight-etb10.c

···
 	struct clk		*atclk;
 	struct coresight_device	*csdev;
 	struct miscdevice	miscdev;
-	spinlock_t		spinlock;
+	raw_spinlock_t		spinlock;
 	local_t			reading;
 	pid_t			pid;
 	u8			*buf;
···
 	unsigned long flags;
 	struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
-	spin_lock_irqsave(&drvdata->spinlock, flags);
+	raw_spin_lock_irqsave(&drvdata->spinlock, flags);
 
 	/* Don't messup with perf sessions. */
 	if (coresight_get_mode(csdev) == CS_MODE_PERF) {
···
 
 	csdev->refcnt++;
 out:
-	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+	raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
 	return ret;
 }
 
···
 	struct perf_output_handle *handle = data;
 	struct cs_buffers *buf = etm_perf_sink_config(handle);
 
-	spin_lock_irqsave(&drvdata->spinlock, flags);
+	raw_spin_lock_irqsave(&drvdata->spinlock, flags);
 
 	/* No need to continue if the component is already in used by sysFS. */
 	if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS) {
···
 	}
 
 out:
-	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+	raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
 	return ret;
 }
 
···
 	struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 	unsigned long flags;
 
-	spin_lock_irqsave(&drvdata->spinlock, flags);
+	raw_spin_lock_irqsave(&drvdata->spinlock, flags);
 
 	csdev->refcnt--;
 	if (csdev->refcnt) {
-		spin_unlock_irqrestore(&drvdata->spinlock, flags);
+		raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
 		return -EBUSY;
 	}
 
···
 	/* Dissociate from monitored process. */
 	drvdata->pid = -1;
 	coresight_set_mode(csdev, CS_MODE_DISABLED);
-	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+	raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
 	dev_dbg(&csdev->dev, "ETB disabled\n");
 	return 0;
···
 
 	capacity = drvdata->buffer_depth * ETB_FRAME_SIZE_WORDS;
 
-	spin_lock_irqsave(&drvdata->spinlock, flags);
+	raw_spin_lock_irqsave(&drvdata->spinlock, flags);
 
 	/* Don't do anything if another tracer is using this sink */
 	if (csdev->refcnt != 1)
···
 	__etb_enable_hw(drvdata);
 	CS_LOCK(drvdata->base);
 out:
-	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+	raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
 	return to_read;
 }
···
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&drvdata->spinlock, flags);
+	raw_spin_lock_irqsave(&drvdata->spinlock, flags);
 	if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS) {
 		__etb_disable_hw(drvdata);
 		etb_dump_hw(drvdata);
 		__etb_enable_hw(drvdata);
 	}
-	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+	raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
 	dev_dbg(&drvdata->csdev->dev, "ETB dumped\n");
 }
···
 	drvdata->base = base;
 	desc.access = CSDEV_ACCESS_IOMEM(base);
 
-	spin_lock_init(&drvdata->spinlock);
+	raw_spin_lock_init(&drvdata->spinlock);
 
 	drvdata->buffer_depth = etb_get_buffer_depth(drvdata);