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

[Shahaf Shuler <shahafs@mellanox.com>]

Hi Nelio, 

Friday, July 13, 2018 4:54 PM, Nelio Laranjeiro:
> Subject: [PATCH] net/mlx5: fix representors detection
> 
> 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>
> Acked-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
> ---
>  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
> df7f39844..8174947f3 100644
> --- a/drivers/net/mlx5/mlx5.c
> +++ b/drivers/net/mlx5/mlx5.c
> @@ -1306,7 +1306,8 @@ 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, @@
> -1325,7 +1326,9 @@ 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))) {

I find this logic a bit complex to be under a single if statement. Can you simplify it w/ local variables? 

>  			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
> cc01310e0..fff88b1d6 100644
> --- a/drivers/net/mlx5/mlx5.h
> +++ b/drivers/net/mlx5/mlx5.h
> @@ -254,6 +254,8 @@ 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 05f66f7b6..101be4791 100644
> --- a/drivers/net/mlx5/mlx5_ethdev.c
> +++ b/drivers/net/mlx5/mlx5_ethdev.c
> @@ -1296,3 +1296,56 @@ 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)
> +		goto error;

This goto is not correct. 
Representors will indeed be able to read, but PFs will not be able to open the phys_port_name (as there is none).
The phys_switch_id is accessible form both. 

I pasted a suggestion below[1], let me know what you think. 

> +	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)
> +		goto error;
> +	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;
> +error:
> +	rte_errno = errno;
> +	return -rte_errno;
> +}
> --
> 2.18.0

[1]
diff --git a/drivers/net/mlx5/mlx5_ethdev.c b/drivers/net/mlx5/mlx5_ethdev.c
index 6cfe02d..b64eb20 100644
--- a/drivers/net/mlx5/mlx5_ethdev.c
+++ b/drivers/net/mlx5/mlx5_ethdev.c
@@ -1328,23 +1328,20 @@ struct ethtool_link_settings {
              ifname);
 
        file = fopen(phys_port_name, "rb");
-       if (file == NULL)
-               goto error;
-       port_name_set = fscanf(file, "%d%c", &data.port_name, &c) == 2 &&
-               c == '\n';
-       fclose(file);
+       if (file) {
+               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)
-               goto error;
-       port_switch_id_set =
-               fscanf(file, "%" SCNx64 "%c", &data.switch_id, &c) == 2 &&
-               c == '\n';
-       fclose(file);
+       if (file) {
+               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;