[dpdk-stable] [PATCH] net/mlx5: fix file path location of HW counters

[Shy Shyman <shys@mellanox.com>]

When debugging performance of a DPDK application the user may
need to view the different statistics of DPDK(for example out_of_buffer)
This can be enabled by using testpmd command 'show port xstats
<port_id>' for example.

The current implementation assumes legacy mode in which the
counters
are at <ibdev_path>/<port_id>/hw_counters/<file_name>.
In switchdev mode the counters file is located right after the device
name, hence resides at <ibdev_path>/hw_counters.

The fix tries to open the path in the second location after a failure
to open the file from the first location.

Fixes: 9c0a9eed37f1 ("net/mlx5: switch to the names in the shared IB context")

Cc: stable@dpdk.org
Cc: viacheslavo@mellanox.com

Signed-off-by: Shy Shyman <shys@mellanox.com>
---
 drivers/net/mlx5/linux/mlx5_os.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/net/mlx5/linux/mlx5_os.c b/drivers/net/mlx5/linux/mlx5_os.c
index 2dc57b20ef..0edc96299c 100644
--- a/drivers/net/mlx5/linux/mlx5_os.c
+++ b/drivers/net/mlx5/linux/mlx5_os.c
@@ -1948,10 +1948,20 @@ mlx5_os_read_dev_stat(struct mlx5_priv *priv, const char *ctr_name,
 
 	if (priv->sh) {
 		MKSTR(path, "%s/ports/%d/hw_counters/%s",
-			  priv->sh->ibdev_path,
-			  priv->dev_port,
-			  ctr_name);
+		      priv->sh->ibdev_path,
+		      priv->dev_port,
+		      ctr_name);
 		fd = open(path, O_RDONLY);
+		/*
+  		 * in switchdev the file location is not per port
+		 * but rather in <ibdev_path>/hw_counters/<file_name>.
+		*/
+		if (fd == -1) {
+			MKSTR(path1, "%s/hw_counters/%s",
+			      priv->sh->ibdev_path,
+			      ctr_name);
+			fd = open(path1, O_RDONLY);
+		}
 		if (fd != -1) {
 			char buf[21] = {'\0'};
 			ssize_t n = read(fd, buf, sizeof(buf));
-- 
2.21.0