[dpdk-dev] [PATCH v2] net/mlx5: fix representors detection

[Nelio Laranjeiro <nelio.laranjeiro@6wind.com>]

On systems where the required Netlink commands are not supported but
Mellanox OFED is installed, representors information must be retrieved
through sysfs.

Fixes: 4c10141488fe ("net/mlx5: add port representor awareness")

Signed-off-by: Nelio Laranjeiro <nelio.laranjeiro@6wind.com>

---

Changes in v2:

On some distribution, the PF may not be able to open the sysfs file,
such issue should not be handled as an error.
---
 drivers/net/mlx5/mlx5.c        |  7 +++--
 drivers/net/mlx5/mlx5.h        |  2 ++
 drivers/net/mlx5/mlx5_ethdev.c | 53 ++++++++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c
index 78a69228e..a1c0ad70a 100644
--- a/drivers/net/mlx5/mlx5.c
+++ b/drivers/net/mlx5/mlx5.c
@@ -1330,7 +1330,8 @@ mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 	 * Netlink calls assuming kernel drivers are recent enough to
 	 * support them.
 	 *
-	 * In the event of identification failure through Netlink, either:
+	 * In the event of identification failure through Netlink, try again
+	 * through sysfs, then either:
 	 *
 	 * 1. No device matches (n == 0), complain and bail out.
 	 * 2. A single IB device matches (n == 1) and is not a representor,
@@ -1349,7 +1350,9 @@ mlx5_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 		if (nl_route < 0 ||
 		    !list[i].ifindex ||
 		    mlx5_nl_switch_info(nl_route, list[i].ifindex,
-					&list[i].info)) {
+					&list[i].info) ||
+		    ((!list[i].info.representor && !list[i].info.master) &&
+		     mlx5_sysfs_switch_info(list[i].ifindex, &list[i].info))) {
 			list[i].ifindex = 0;
 			memset(&list[i].info, 0, sizeof(list[i].info));
 			continue;
diff --git a/drivers/net/mlx5/mlx5.h b/drivers/net/mlx5/mlx5.h
index db8a5fa01..a7f50b31f 100644
--- a/drivers/net/mlx5/mlx5.h
+++ b/drivers/net/mlx5/mlx5.h
@@ -273,6 +273,8 @@ eth_rx_burst_t mlx5_select_rx_function(struct rte_eth_dev *dev);
 unsigned int mlx5_dev_to_port_id(const struct rte_device *dev,
 				 uint16_t *port_list,
 				 unsigned int port_list_n);
+int mlx5_sysfs_switch_info(unsigned int ifindex,
+			   struct mlx5_switch_info *info);
 
 /* mlx5_mac.c */
 
diff --git a/drivers/net/mlx5/mlx5_ethdev.c b/drivers/net/mlx5/mlx5_ethdev.c
index 9cf2dc5f1..4a24f8021 100644
--- a/drivers/net/mlx5/mlx5_ethdev.c
+++ b/drivers/net/mlx5/mlx5_ethdev.c
@@ -1321,3 +1321,56 @@ mlx5_dev_to_port_id(const struct rte_device *dev, uint16_t *port_list,
 	}
 	return n;
 }
+
+/**
+ * Get switch information associated with network interface.
+ *
+ * @param ifindex
+ *   Network interface index.
+ * @param[out] info
+ *   Switch information object, populated in case of success.
+ *
+ * @return
+ *   0 on success, a negative errno value otherwise and rte_errno is set.
+ */
+int
+mlx5_sysfs_switch_info(unsigned int ifindex, struct mlx5_switch_info *info)
+{
+	char ifname[IF_NAMESIZE];
+	FILE *file;
+	struct mlx5_switch_info data = { .master = 0, };
+	bool port_name_set = false;
+	bool port_switch_id_set = false;
+	char c;
+
+	if (!if_indextoname(ifindex, ifname)) {
+		rte_errno = errno;
+		return -rte_errno;
+	}
+
+	MKSTR(phys_port_name, "/sys/class/net/%s/phys_port_name",
+	      ifname);
+	MKSTR(phys_switch_id, "/sys/class/net/%s/phys_switch_id",
+	      ifname);
+
+	file = fopen(phys_port_name, "rb");
+	if (file != NULL) {
+		port_name_set =
+			fscanf(file, "%d%c", &data.port_name, &c) == 2 &&
+			c == '\n';
+		fclose(file);
+	}
+	file = fopen(phys_switch_id, "rb");
+	if (file == NULL) {
+		rte_errno = errno;
+		return -rte_errno;
+	}
+	port_switch_id_set =
+		fscanf(file, "%" SCNx64 "%c", &data.switch_id, &c) == 2 &&
+		c == '\n';
+	fclose(file);
+	data.master = port_switch_id_set && !port_name_set;
+	data.representor = port_switch_id_set && port_name_set;
+	*info = data;
+	return 0;
+}
-- 
2.18.0