1 files changed, 29 insertions, 57 deletions

diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
index 5e93b52df105..b8d6520d47c9 100644
--- a/drivers/hwtracing/coresight/coresight-core.c
+++ b/drivers/hwtracing/coresight/coresight-core.c
@@ -279,29 +279,18 @@ EXPORT_SYMBOL_GPL(coresight_add_helper);
 static int coresight_enable_sink(struct coresight_device *csdev,
 				 enum cs_mode mode, void *data)
 {
-	int ret = sink_ops(csdev)->enable(csdev, mode, data);
-
-	if (ret)
-		return ret;
-
-	csdev->enable = true;
-
-	return 0;
+	return sink_ops(csdev)->enable(csdev, mode, data);
 }
 
 static void coresight_disable_sink(struct coresight_device *csdev)
 {
-	int ret = sink_ops(csdev)->disable(csdev);
-	if (ret)
-		return;
-	csdev->enable = false;
+	sink_ops(csdev)->disable(csdev);
 }
 
 static int coresight_enable_link(struct coresight_device *csdev,
 				 struct coresight_device *parent,
 				 struct coresight_device *child)
 {
-	int ret = 0;
 	int link_subtype;
 	struct coresight_connection *inconn, *outconn;
 
@@ -317,19 +306,13 @@ static int coresight_enable_link(struct coresight_device *csdev,
 	if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_SPLIT && IS_ERR(outconn))
 		return PTR_ERR(outconn);
 
-	ret = link_ops(csdev)->enable(csdev, inconn, outconn);
-	if (!ret)
-		csdev->enable = true;
-
-	return ret;
+	return link_ops(csdev)->enable(csdev, inconn, outconn);
 }
 
 static void coresight_disable_link(struct coresight_device *csdev,
 				   struct coresight_device *parent,
 				   struct coresight_device *child)
 {
-	int i;
-	int link_subtype;
 	struct coresight_connection *inconn, *outconn;
 
 	if (!parent || !child)
@@ -337,26 +320,8 @@ static void coresight_disable_link(struct coresight_device *csdev,
 
 	inconn = coresight_find_out_connection(parent, csdev);
 	outconn = coresight_find_out_connection(csdev, child);
-	link_subtype = csdev->subtype.link_subtype;
 
 	link_ops(csdev)->disable(csdev, inconn, outconn);
-
-	if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG) {
-		for (i = 0; i < csdev->pdata->nr_inconns; i++)
-			if (atomic_read(&csdev->pdata->in_conns[i]->dest_refcnt) !=
-			    0)
-				return;
-	} else if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_SPLIT) {
-		for (i = 0; i < csdev->pdata->nr_outconns; i++)
-			if (atomic_read(&csdev->pdata->out_conns[i]->src_refcnt) !=
-			    0)
-				return;
-	} else {
-		if (atomic_read(&csdev->refcnt) != 0)
-			return;
-	}
-
-	csdev->enable = false;
 }
 
 int coresight_enable_source(struct coresight_device *csdev, enum cs_mode mode,
@@ -364,11 +329,16 @@ int coresight_enable_source(struct coresight_device *csdev, enum cs_mode mode,
 {
 	int ret;
 
-	if (!csdev->enable) {
+	/*
+	 * Comparison with CS_MODE_SYSFS works without taking any device
+	 * specific spinlock because the truthyness of that comparison can only
+	 * change with coresight_mutex held, which we already have here.
+	 */
+	lockdep_assert_held(&coresight_mutex);
+	if (local_read(&csdev->mode) != CS_MODE_SYSFS) {
 		ret = source_ops(csdev)->enable(csdev, data, mode);
 		if (ret)
 			return ret;
-		csdev->enable = true;
 	}
 
 	atomic_inc(&csdev->refcnt);
@@ -385,22 +355,12 @@ static bool coresight_is_helper(struct coresight_device *csdev)
 static int coresight_enable_helper(struct coresight_device *csdev,
 				   enum cs_mode mode, void *data)
 {
-	int ret = helper_ops(csdev)->enable(csdev, mode, data);
-
-	if (ret)
-		return ret;
-
-	csdev->enable = true;
-	return 0;
+	return helper_ops(csdev)->enable(csdev, mode, data);
 }
 
 static void coresight_disable_helper(struct coresight_device *csdev)
 {
-	int ret = helper_ops(csdev)->disable(csdev, NULL);
-
-	if (ret)
-		return;
-	csdev->enable = false;
+	helper_ops(csdev)->disable(csdev, NULL);
 }
 
 static void coresight_disable_helpers(struct coresight_device *csdev)
@@ -445,11 +405,15 @@ EXPORT_SYMBOL_GPL(coresight_disable_source);
 static bool coresight_disable_source_sysfs(struct coresight_device *csdev,
 					   void *data)
 {
+	lockdep_assert_held(&coresight_mutex);
+	if (local_read(&csdev->mode) != CS_MODE_SYSFS)
+		return false;
+
 	if (atomic_dec_return(&csdev->refcnt) == 0) {
 		coresight_disable_source(csdev, data);
-		csdev->enable = false;
+		return true;
 	}
-	return !csdev->enable;
+	return false;
 }
 
 /*
@@ -1097,7 +1061,13 @@ int coresight_enable(struct coresight_device *csdev)
 	if (ret)
 		goto out;
 
-	if (csdev->enable) {
+	/*
+	 * mode == SYSFS implies that it's already enabled. Don't look at the
+	 * refcount to determine this because we don't claim the source until
+	 * coresight_enable_source() so can still race with Perf mode which
+	 * doesn't hold coresight_mutex.
+	 */
+	if (local_read(&csdev->mode) == CS_MODE_SYSFS) {
 		/*
 		 * There could be multiple applications driving the software
 		 * source. So keep the refcount for each such user when the
@@ -1183,7 +1153,7 @@ void coresight_disable(struct coresight_device *csdev)
 	if (ret)
 		goto out;
 
-	if (!csdev->enable || !coresight_disable_source_sysfs(csdev, NULL))
+	if (!coresight_disable_source_sysfs(csdev, NULL))
 		goto out;
 
 	switch (csdev->subtype.source_subtype) {
@@ -1249,7 +1219,9 @@ static ssize_t enable_source_show(struct device *dev,
 {
 	struct coresight_device *csdev = to_coresight_device(dev);
 
-	return scnprintf(buf, PAGE_SIZE, "%u\n", csdev->enable);
+	guard(mutex)(&coresight_mutex);
+	return scnprintf(buf, PAGE_SIZE, "%u\n",
+			 local_read(&csdev->mode) == CS_MODE_SYSFS);
 }
 
 static ssize_t enable_source_store(struct device *dev,