[PATCH v13 17/28] coresight: Use helpers to fetch first and last nodes

[Leo Yan]

Replace open code with coresight_path_first_node() and
coresight_path_last_node() for fetching the nodes.

Check that the node is not NULL before accessing csdev field.

Tested-by: Jie Gan <jie.gan at oss.qualcomm.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun at arm.com>
Reviewed-by: James Clark <james.clark at linaro.org>
Tested-by: James Clark <james.clark at linaro.org>
Signed-off-by: Leo Yan <leo.yan at arm.com>
---
 drivers/hwtracing/coresight/coresight-core.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
index 62a12a90988949ccc8c181c8edde7939e4f986ab..61ae7b6c7a836caafaf87787af91a1f5326c16ec 100644
--- a/drivers/hwtracing/coresight/coresight-core.c
+++ b/drivers/hwtracing/coresight/coresight-core.c
@@ -174,11 +174,16 @@ void coresight_put_percpu_source_ref(struct coresight_device *csdev)
 struct coresight_device *coresight_get_source(struct coresight_path *path)
 {
 	struct coresight_device *csdev;
+	struct coresight_node *nd;
 
 	if (!path)
 		return NULL;
 
-	csdev = list_first_entry(&path->path_list, struct coresight_node, link)->csdev;
+	nd = coresight_path_first_node(path);
+	if (!nd)
+		return NULL;
+
+	csdev = nd->csdev;
 	if (!coresight_is_device_source(csdev))
 		return NULL;
 
@@ -711,11 +716,16 @@ int coresight_enable_path(struct coresight_path *path, enum cs_mode mode)
 struct coresight_device *coresight_get_sink(struct coresight_path *path)
 {
 	struct coresight_device *csdev;
+	struct coresight_node *nd;
 
 	if (!path)
 		return NULL;
 
-	csdev = list_last_entry(&path->path_list, struct coresight_node, link)->csdev;
+	nd = coresight_path_last_node(path);
+	if (!nd)
+		return NULL;
+
+	csdev = nd->csdev;
 	if (csdev->type != CORESIGHT_DEV_TYPE_SINK &&
 	    csdev->type != CORESIGHT_DEV_TYPE_LINKSINK)
 		return NULL;

-- 
2.34.1