[dpdk-dev] [PATCH v2 1/1] net/mlx5: fix device probing for old kernel drivers

[Viacheslav Ovsiienko]

Retrieving network interface index via Netlink fails in
case of old ib_core kernel driver installed - mlx5_nl_ifindex()
routine fails due to RDMA_NLDEV_ATTR_NDEV_INDEX attribute is not
supported by the old driver.

The patch allowing to retrieve the network interface index and
name via Netlink [1]. So, the problem depends on ib_core module
version - 4.16 supports getting ifindex via Netlink, 4.15 does not.

This error was ignored in previous versions of MLX5 PMD probing
routine. For single device ifindex was retrieved via sysfs
and link control was not lost, so problem just was not noticed.
In order to support MLX5 PMD functioning over old kernel driver
this patch adds ifindex retrieving via sysfs into probing routine.
It is worth to note this method works for master/standalone
device only.

[1] https://www.spinics.net/lists/linux-rdma/msg62948.html
    Linux tree: 5b2cc79d (Leon Romanovsky 2018-03-27 20:40:49 +0300 270)

Fixes: ad74bc619504 ("net/mlx5: support multiport IB device during probing")

Signed-off-by: Viacheslav Ovsiienko <viacheslavo at mellanox.com>
---

v2: 
    comments and log message update
v1: 
    http://patches.dpdk.org/patch/52192/

 drivers/net/mlx5/mlx5.c        | 36 ++++++++++++++++++++++++++++++++----
 drivers/net/mlx5/mlx5.h        |  1 +
 drivers/net/mlx5/mlx5_ethdev.c | 28 ++++++++++++++--------------
 3 files changed, 47 insertions(+), 18 deletions(-)

diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index 09f4a21..b7e6234 100644
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -1888,12 +1888,40 @@ struct mlx5_dev_spawn_data {
 				list[ns].ifindex = mlx5_nl_ifindex
 					(nl_rdma, list[ns].ibv_dev->name, 1);
 			if (!list[ns].ifindex) {
+				char ifname[IF_NAMESIZE];
+
 				/*
-				 * No network interface index found for the
-				 * specified device, it means there it is not
-				 * a representor/master.
+				 * Netlink failed, it may happen with old
+				 * ib_core kernel driver (before 4.16).
+				 * We can assume there is old driver because
+				 * here we are processing single ports IB
+				 * devices. Let's try sysfs to retrieve
+				 * the ifindex. The method works for
+				 * master device only.
 				 */
-				continue;
+				if (nd > 1) {
+					/*
+					 * Multiple devices found, assume
+					 * representors, can not distinguish
+					 * master/representor and retrieve
+					 * ifindex via sysfs.
+					 */
+					continue;
+				}
+				ret = mlx5_get_master_ifname
+					(ibv_match[i]->ibdev_path, &ifname);
+				if (!ret)
+					list[ns].ifindex =
+						if_nametoindex(ifname);
+				if (!list[ns].ifindex) {
+					/*
+					 * No network interface index found
+					 * for the specified device, it means
+					 * there it is neither representor
+					 * nor master.
+					 */
+					continue;
+				}
 			}
 			ret = -1;
 			if (nl_route >= 0)
diff --git a/drivers/net/mlx5/mlx5.h b/drivers/net/mlx5/mlx5.h
index ef05d9f..c9b2251 100644
--- a/drivers/net/mlx5/mlx5.h
+++ b/drivers/net/mlx5/mlx5.h
@@ -364,6 +364,7 @@ struct mlx5_priv {
 /* mlx5_ethdev.c */
 
 int mlx5_get_ifname(const struct rte_eth_dev *dev, char (*ifname)[IF_NAMESIZE]);
+int mlx5_get_master_ifname(const char *ibdev_path, char (*ifname)[IF_NAMESIZE]);
 unsigned int mlx5_ifindex(const struct rte_eth_dev *dev);
 int mlx5_ifreq(const struct rte_eth_dev *dev, int req, struct ifreq *ifr);
 int mlx5_get_mtu(struct rte_eth_dev *dev, uint16_t *mtu);
diff --git a/drivers/net/mlx5/mlx5_ethdev.c b/drivers/net/mlx5/mlx5_ethdev.c
index 9ae9ddd..1e6fe19 100644
--- a/drivers/net/mlx5/mlx5_ethdev.c
+++ b/drivers/net/mlx5/mlx5_ethdev.c
@@ -127,21 +127,18 @@ struct ethtool_link_settings {
  * @return
  *   0 on success, a negative errno value otherwise and rte_errno is set.
  */
-static int
-mlx5_get_master_ifname(const struct rte_eth_dev *dev,
-		       char (*ifname)[IF_NAMESIZE])
+int
+mlx5_get_master_ifname(const char *ibdev_path, char (*ifname)[IF_NAMESIZE])
 {
-	struct mlx5_priv *priv = dev->data->dev_private;
 	DIR *dir;
 	struct dirent *dent;
 	unsigned int dev_type = 0;
 	unsigned int dev_port_prev = ~0u;
 	char match[IF_NAMESIZE] = "";
 
-	assert(priv);
-	assert(priv->sh);
+	assert(ibdev_path);
 	{
-		MKSTR(path, "%s/device/net", priv->sh->ibdev_path);
+		MKSTR(path, "%s/device/net", ibdev_path);
 
 		dir = opendir(path);
 		if (dir == NULL) {
@@ -161,7 +158,7 @@ struct ethtool_link_settings {
 			continue;
 
 		MKSTR(path, "%s/device/net/%s/%s",
-		      priv->sh->ibdev_path, name,
+		      ibdev_path, name,
 		      (dev_type ? "dev_id" : "dev_port"));
 
 		file = fopen(path, "rb");
@@ -222,15 +219,18 @@ struct ethtool_link_settings {
 mlx5_get_ifname(const struct rte_eth_dev *dev, char (*ifname)[IF_NAMESIZE])
 {
 	struct mlx5_priv *priv = dev->data->dev_private;
-	unsigned int ifindex =
-		priv->nl_socket_rdma >= 0 ?
-		mlx5_nl_ifindex(priv->nl_socket_rdma,
-				priv->sh->ibdev_name,
-				priv->ibv_port) : 0;
+	unsigned int ifindex;
 
+	assert(priv);
+	assert(priv->sh);
+	ifindex = priv->nl_socket_rdma >= 0 ?
+		  mlx5_nl_ifindex(priv->nl_socket_rdma,
+				  priv->sh->ibdev_name,
+				  priv->ibv_port) : 0;
 	if (!ifindex) {
 		if (!priv->representor)
-			return mlx5_get_master_ifname(dev, ifname);
+			return mlx5_get_master_ifname(priv->sh->ibdev_path,
+						      ifname);
 		rte_errno = ENXIO;
 		return -rte_errno;
 	}
-- 
1.8.3.1