[PATCH 09/28] drm/dp_mst: Refactor build_mst_prop_path() to use seq_buf

[Bill Wendling]

build_mst_prop_path() constructs an MST property path by formatting port
numbers into a temporary buffer and appending them to "proppath" with
strlcat() in a loop.

In preparation for removing the deprecated strlcat() API[1], use struct
seq_buf and seq_buf_printf() to format the path components directly into
"proppath", eliminating the temporary buffer and repeated string scans.

Link: https://github.com/KSPP/linux/issues/370 [1]
Cc: codemender-patching+linux@xxxxxxxxxx
Assisted-by: Claude-3-5-Sonnet:20241022 [editor_update_file, make_kernel_build_single_file]
Signed-off-by: Bill Wendling <morbo@xxxxxxxxxx>
---
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---
 drivers/gpu/drm/display/drm_dp_mst_topology.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 7ce9e212770a..229b5fec44bf 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -29,6 +29,7 @@
 #include <linux/kernel.h>
 #include <linux/random.h>
 #include <linux/sched.h>
+#include <linux/seq_buf.h>
 #include <linux/seq_file.h>
 
 #if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
@@ -2216,19 +2217,21 @@ static void build_mst_prop_path(const struct drm_dp_mst_branch *mstb,
 				char *proppath,
 				size_t proppath_size)
 {
+	struct seq_buf s;
 	int i;
-	char temp[8];
 
-	snprintf(proppath, proppath_size, "mst:%d", mstb->mgr->conn_base_id);
+	seq_buf_init(&s, proppath, proppath_size);
+
+	seq_buf_printf(&s, "mst:%d", mstb->mgr->conn_base_id);
 	for (i = 0; i < (mstb->lct - 1); i++) {
 		int shift = (i % 2) ? 0 : 4;
 		int port_num = (mstb->rad[i / 2] >> shift) & 0xf;
 
-		snprintf(temp, sizeof(temp), "-%d", port_num);
-		strlcat(proppath, temp, proppath_size);
+		seq_buf_printf(&s, "-%d", port_num);
 	}
-	snprintf(temp, sizeof(temp), "-%d", pnum);
-	strlcat(proppath, temp, proppath_size);
+	seq_buf_printf(&s, "-%d", pnum);
+
+	seq_buf_str(&s);
 }
 
 /**
-- 
2.55.0.1032.g73a4cd73de-goog