Subject: [PATCH v2] coresight: fix missing error code when trace ID is invalid

From: Jie Gan <[email-masked]>
Date: Sat, 09 May 2026 08:58:46 +0800

When coresight_path_assign_trace_id() cannot assign a valid trace ID,
coresight_enable_sysfs() takes the err_path goto with ret still 0,
returning success to the caller despite no trace session being started.

Fix this by changing coresight_path_assign_trace_id() to return int.
Move the IS_VALID_CS_TRACE_ID() check inside the function so it returns
-EINVAL on failure and 0 on success. Update coresight_enable_sysfs() to
check the return value directly instead of inspecting path->trace_id
after the call.

The other caller in coresight-etm-perf.c discards the return value and
continues to check path->trace_id via IS_VALID_CS_TRACE_ID() directly.
This is unaffected: on failure path->trace_id is no longer written, so
it remains 0, which IS_VALID_CS_TRACE_ID() rejects the same as before.

Fixes: d87d76d823d1 ("Coresight: Allocate trace ID after building the path")
Signed-off-by: Jie Gan <[email-masked]>
---
Changes in v2:
- Refactor the coresight_path_assign_trace_id function.
- Link to v1: https://lore.kernel.org/r/[email-masked]
---
 drivers/hwtracing/coresight/coresight-core.c  | 14 ++++++++++----
 drivers/hwtracing/coresight/coresight-priv.h  |  2 +-
 drivers/hwtracing/coresight/coresight-sysfs.c |  4 ++--
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
index 46f247f73cf6..cabdc0c72f38 100644
--- a/drivers/hwtracing/coresight/coresight-core.c
+++ b/drivers/hwtracing/coresight/coresight-core.c
@@ -739,12 +739,12 @@ static int coresight_get_trace_id(struct coresight_device *csdev,
  * Call this after creating the path and before enabling it. This leaves
  * the trace ID set on the path, or it remains 0 if it couldn't be assigned.
  */
-void coresight_path_assign_trace_id(struct coresight_path *path,
+int coresight_path_assign_trace_id(struct coresight_path *path,
 				    enum cs_mode mode)
 {
 	struct coresight_device *sink = coresight_get_sink(path);
 	struct coresight_node *nd;
-	int trace_id;
+	int trace_id, ret = -EINVAL;
 
 	list_for_each_entry(nd, &path->path_list, link) {
 		/* Assign a trace ID to the path for the first device that wants to do it */
@@ -755,10 +755,16 @@ void coresight_path_assign_trace_id(struct coresight_path *path,
 		 * Non 0 is either success or fail.
 		 */
 		if (trace_id != 0) {
-			path->trace_id = trace_id;
-			return;
+			if (IS_VALID_CS_TRACE_ID(trace_id)) {
+				path->trace_id = trace_id;
+				ret = 0;
+			}
+
+			return ret;
 		}
 	}
+
+	return ret;
 }
 
 /**
diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
index 1ea882dffd70..34c7e792adbd 100644
--- a/drivers/hwtracing/coresight/coresight-priv.h
+++ b/drivers/hwtracing/coresight/coresight-priv.h
@@ -153,7 +153,7 @@ int coresight_make_links(struct coresight_device *orig,
 void coresight_remove_links(struct coresight_device *orig,
 			    struct coresight_connection *conn);
 u32 coresight_get_sink_id(struct coresight_device *csdev);
-void coresight_path_assign_trace_id(struct coresight_path *path,
+int coresight_path_assign_trace_id(struct coresight_path *path,
 				   enum cs_mode mode);
 
 #if IS_ENABLED(CONFIG_CORESIGHT_SOURCE_ETM3X)
diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c
index d2a6ed8bcc74..b6a870399e83 100644
--- a/drivers/hwtracing/coresight/coresight-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-sysfs.c
@@ -211,8 +211,8 @@ int coresight_enable_sysfs(struct coresight_device *csdev)
 		goto out;
 	}
 
-	coresight_path_assign_trace_id(path, CS_MODE_SYSFS);
-	if (!IS_VALID_CS_TRACE_ID(path->trace_id))
+	ret = coresight_path_assign_trace_id(path, CS_MODE_SYSFS);
+	if (ret)
 		goto err_path;
 
 	ret = coresight_enable_path(path, CS_MODE_SYSFS);

---
base-commit: 17c7841d09ee7d33557fd075562d9289b6018c90
change-id: 20260508-fix-trace-id-error-dbfdd4d8f2d1

Best regards,
-- 
Jie Gan <[email-masked]>