[PATCH v4 10/10] coresight: ultrasoc-smb: Remove sharing guards from SMB

[James Clark <james.clark@linaro.org>]

Potential sink sharing is now identified during AUX setup. Trust the
core sharing rules when enabling an event and use the sink reference
count to avoid reconfiguring hardware that is already active.

Remove the redundant PID tracking from SMB and the now-unused PID
field from the common cs_buffers structure.

Signed-off-by: James Clark <james.clark@linaro.org>
---
 drivers/hwtracing/coresight/coresight-priv.h |  2 --
 drivers/hwtracing/coresight/ultrasoc-smb.c   | 20 +-------------------
 drivers/hwtracing/coresight/ultrasoc-smb.h   |  3 ---
 3 files changed, 1 insertion(+), 24 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
index 51313fe2cd0e..9eabfdfa32e1 100644
--- a/drivers/hwtracing/coresight/coresight-priv.h
+++ b/drivers/hwtracing/coresight/coresight-priv.h
@@ -95,7 +95,6 @@ enum etm_addr_type {
  * struct cs_buffer - keep track of a recording session' specifics
  * @cur:	index of the current buffer
  * @nr_pages:	max number of pages granted to us
- * @pid:	PID this cs_buffer belongs to
  * @offset:	offset within the current buffer
  * @data_size:	how much we collected in this run
  * @snapshot:	is this run in snapshot mode
@@ -104,7 +103,6 @@ enum etm_addr_type {
 struct cs_buffers {
 	unsigned int		cur;
 	unsigned int		nr_pages;
-	pid_t			pid;
 	unsigned long		offset;
 	local_t			data_size;
 	bool			snapshot;
diff --git a/drivers/hwtracing/coresight/ultrasoc-smb.c b/drivers/hwtracing/coresight/ultrasoc-smb.c
index b107d4606fcd..f2efbb615cda 100644
--- a/drivers/hwtracing/coresight/ultrasoc-smb.c
+++ b/drivers/hwtracing/coresight/ultrasoc-smb.c
@@ -214,23 +214,9 @@ static int smb_enable_perf(struct coresight_device *csdev,
 			   struct coresight_path *path)
 {
 	struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
-	struct perf_output_handle *handle = path->handle;
-	struct cs_buffers *buf = etm_perf_sink_config(handle);
-	pid_t pid;
 
-	if (!buf)
-		return -EINVAL;
-
-	/* Get a handle on the pid of the target process */
-	pid = buf->pid;
-
-	/* Device is already in used by other session */
-	if (drvdata->pid != -1 && drvdata->pid != pid)
-		return -EBUSY;
-
-	if (drvdata->pid == -1) {
+	if (!csdev->refcnt) {
 		smb_enable_hw(drvdata);
-		drvdata->pid = pid;
 		coresight_set_mode(csdev, CS_MODE_PERF);
 	}
 
@@ -292,8 +278,6 @@ static int smb_disable(struct coresight_device *csdev)
 
 	smb_disable_hw(drvdata);
 
-	/* Dissociate from the target process. */
-	drvdata->pid = -1;
 	coresight_set_mode(csdev, CS_MODE_DISABLED);
 	dev_dbg(&csdev->dev, "Ultrasoc SMB disabled\n");
 
@@ -315,7 +299,6 @@ static void *smb_alloc_buffer(struct coresight_device *csdev,
 	buf->snapshot = overwrite;
 	buf->nr_pages = nr_pages;
 	buf->data_pages = pages;
-	buf->pid = task_pid_nr(event->owner);
 
 	return buf;
 }
@@ -563,7 +546,6 @@ static int smb_probe(struct platform_device *pdev)
 	smb_reset_buffer(drvdata);
 	platform_set_drvdata(pdev, drvdata);
 	raw_spin_lock_init(&drvdata->spinlock);
-	drvdata->pid = -1;
 
 	ret = smb_register_sink(pdev, drvdata);
 	if (ret) {
diff --git a/drivers/hwtracing/coresight/ultrasoc-smb.h b/drivers/hwtracing/coresight/ultrasoc-smb.h
index 323f0ccb6878..561e42dc0870 100644
--- a/drivers/hwtracing/coresight/ultrasoc-smb.h
+++ b/drivers/hwtracing/coresight/ultrasoc-smb.h
@@ -108,8 +108,6 @@ struct smb_data_buffer {
  * @miscdev:	Specifics to handle "/dev/xyz.smb" entry.
  * @spinlock:	Control data access to one at a time.
  * @reading:	Synchronise user space access to SMB buffer.
- * @pid:	Process ID of the process being monitored by the
- *		session that is using this component.
  */
 struct smb_drv_data {
 	void __iomem *base;
@@ -118,7 +116,6 @@ struct smb_drv_data {
 	struct miscdevice miscdev;
 	raw_spinlock_t spinlock;
 	bool reading;
-	pid_t pid;
 };
 
 #endif

-- 
2.43.0