[PATCH v5 17/19] coresight: sysfs: Increment refcount only for system tracers

[Leo Yan]

Except for system tracers (e.g. STM), other sources treat multiple
enables as equivalent to a single enable. The device mode already
tracks the binary state, so it is redundant to operate refcount.

Refactor to maintain the refcount only for system sources. This
simplifies future CPU PM handling without refcount logic.

Signed-off-by: Leo Yan <leo.yan at arm.com>
---
 drivers/hwtracing/coresight/coresight-sysfs.c | 35 +++++++++++++++------------
 1 file changed, 19 insertions(+), 16 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c
index 9e94505bccf4ac91207f2f5393ae57ae077d61d6..04c1425eb37d69c6feb8e49446fc58ee57a5e82e 100644
--- a/drivers/hwtracing/coresight/coresight-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-sysfs.c
@@ -58,7 +58,17 @@ static int coresight_enable_source_sysfs(struct coresight_device *csdev,
 			return ret;
 	}
 
-	csdev->refcnt++;
+	/*
+	 * There could be multiple applications driving the software
+	 * source. So keep the refcount for each such user when the
+	 * source is already enabled.
+	 *
+	 * No need to increment the reference counter for other source
+	 * types, as multiple enables are the same as a single enable.
+	 */
+	if (csdev->subtype.source_subtype ==
+			CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE)
+		csdev->refcnt++;
 
 	return 0;
 }
@@ -80,7 +90,10 @@ static bool coresight_disable_source_sysfs(struct coresight_device *csdev,
 	if (coresight_get_mode(csdev) != CS_MODE_SYSFS)
 		return false;
 
-	csdev->refcnt--;
+	if (csdev->subtype.source_subtype ==
+			CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE)
+		csdev->refcnt--;
+
 	if (csdev->refcnt == 0) {
 		coresight_disable_source(csdev, data);
 		return true;
@@ -159,10 +172,7 @@ int coresight_enable_sysfs(struct coresight_device *csdev)
 {
 	int ret = 0;
 	struct coresight_device *sink;
-	struct coresight_path *path;
-	enum coresight_dev_subtype_source subtype;
-
-	subtype = csdev->subtype.source_subtype;
+	struct coresight_path *path = NULL;
 
 	mutex_lock(&coresight_mutex);
 
@@ -176,16 +186,8 @@ int coresight_enable_sysfs(struct coresight_device *csdev)
 	 * coresight_enable_source() so can still race with Perf mode which
 	 * doesn't hold coresight_mutex.
 	 */
-	if (coresight_get_mode(csdev) == CS_MODE_SYSFS) {
-		/*
-		 * There could be multiple applications driving the software
-		 * source. So keep the refcount for each such user when the
-		 * source is already enabled.
-		 */
-		if (subtype == CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE)
-			csdev->refcnt++;
-		goto out;
-	}
+	if (coresight_get_mode(csdev) == CS_MODE_SYSFS)
+		goto enable_source;
 
 	sink = coresight_find_activated_sysfs_sink(csdev);
 	if (!sink) {
@@ -208,6 +210,7 @@ int coresight_enable_sysfs(struct coresight_device *csdev)
 	if (ret)
 		goto err_path;
 
+enable_source:
 	ret = coresight_enable_source_sysfs(csdev, CS_MODE_SYSFS, path);
 	if (ret)
 		goto err_source;

-- 
2.34.1