[PATCH v3] net/mlx5: fix the sysfs port name translation

[Bing Zhao]

With some OFED or upstream kernel of mlx5, the port name fetched from
"/sys/class/net/[DEV]/phys_port_name" may have a tailing "\n" as the
EOL. The sscanf() will return the scanned items number with this EOL.

In such case, the "equal to" condition is considered as false and
the function mlx5_translate_port_name() will recognize the port type
wrongly with UNKNOWN result.

The tailing carriage return character should be removed before
calling the mlx5_translate_port_name(), this was already done in the
NL message handling. In the meanwhile, the possible incorrect line
feed character is also taken into consideration.

Fixes: 654810b56828 ("common/mlx5: share Netlink commands")
Fixes: 420bbdae89f2 ("net/mlx5: fix host physical function representor naming")
Cc: stable at dpdk.org

Signed-off-by: Bing Zhao <bingz at nvidia.com>
---
 drivers/net/mlx5/linux/mlx5_ethdev_os.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/drivers/net/mlx5/linux/mlx5_ethdev_os.c b/drivers/net/mlx5/linux/mlx5_ethdev_os.c
index f1ff6f49f9..55801534d1 100644
--- a/drivers/net/mlx5/linux/mlx5_ethdev_os.c
+++ b/drivers/net/mlx5/linux/mlx5_ethdev_os.c
@@ -1035,7 +1035,8 @@ int
 mlx5_sysfs_switch_info(unsigned int ifindex, struct mlx5_switch_info *info)
 {
 	char ifname[IF_NAMESIZE];
-	char port_name[IF_NAMESIZE];
+	char *port_name = NULL;
+	size_t port_name_size = 0;
 	FILE *file;
 	struct mlx5_switch_info data = {
 		.master = 0,
@@ -1048,6 +1049,7 @@ mlx5_sysfs_switch_info(unsigned int ifindex, struct mlx5_switch_info *info)
 	bool port_switch_id_set = false;
 	bool device_dir = false;
 	char c;
+	ssize_t line_size;
 
 	if (!if_indextoname(ifindex, ifname)) {
 		rte_errno = errno;
@@ -1063,8 +1065,21 @@ mlx5_sysfs_switch_info(unsigned int ifindex, struct mlx5_switch_info *info)
 
 	file = fopen(phys_port_name, "rb");
 	if (file != NULL) {
-		if (fgets(port_name, IF_NAMESIZE, file) != NULL)
+		char *tail_nl;
+
+		line_size = getline(&port_name, &port_name_size, file);
+		if (line_size < 0) {
+			fclose(file);
+			rte_errno = errno;
+			return -rte_errno;
+		} else if (line_size > 0) {
+			/* Remove tailing newline character. */
+			tail_nl = strchr(port_name, '\n');
+			if (tail_nl)
+				*tail_nl = '\0';
 			mlx5_translate_port_name(port_name, &data);
+		}
+		free(port_name);
 		fclose(file);
 	}
 	file = fopen(phys_switch_id, "rb");
-- 
2.31.1