[dpdk-dev] [PATCH 2/2] net/mlx5: fix crash in dev_info_get in secondary process

[Slava Ovsiienko]

Hi, Stephen

>mlx5_get_ifname uses priv->ctx which is not a valid pointer in a secondary process.

1. Sorry, mlx5_priv structure does not contain ctx field.  Do you mean priv->sh  (shared context) ?
This one is allocated with rte_zmalloc(), that supposes shared memory allocation and shared
context structure should be valid within secondary process context.

It seems there is another issue - mlx5_get_ifname() uses priv->nl_socket_rdma
which is process-specific socket handle (fd), so routine may fail.

2. Generally I'm OK with caching ifindex in priv structure - it seems the ifindex is permanent 
throughout interface lifetime. The mlx5_dev_spawn has a parameter mlx5_dev_spawn_data *spawn,
it contains the successfully queried ifindex of the device being spawned - no need to query again.

The cached valued should be retrieved by mlx5_ifindex() routine and  mlx5_get_ifname()
should be refactored to use mlx5_ifindex().

WBR,
Slava

> -----Original Message-----
> From: Stephen Hemminger <stephen at networkplumber.org>
> Sent: Friday, July 12, 2019 23:54
> To: Matan Azrad <matan at mellanox.com>; Shahaf Shuler
> <shahafs at mellanox.com>; Yongseok Koh <yskoh at mellanox.com>; Slava
> Ovsiienko <viacheslavo at mellanox.com>
> Cc: dev at dpdk.org; sju at paloaltonetworks.com; Stephen Hemminger
> <stephen at networkplumber.org>
> Subject: [PATCH 2/2] net/mlx5: fix crash in dev_info_get in secondary
> process
> 
> mlx5_dev_info_get calls mlx5_get_ifname, but mlx5_get_ifname uses priv-
> >ctx which is not a valid pointer in a secondary process. The fix is to cache
> the value in primary.
> 
> In the primary process, get and store the interface index of the device so that
> secondary process can see it.
> 
> Fixes: e60fbd5b24fc ("mlx5: add device configure/start/stop")
> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
> ---
>  drivers/net/mlx5/mlx5.c        | 17 ++++++++---------
>  drivers/net/mlx5/mlx5.h        |  1 +
>  drivers/net/mlx5/mlx5_ethdev.c |  4 +---
>  3 files changed, 10 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/net/mlx5/mlx5.c b/drivers/net/mlx5/mlx5.c index
> d93f92db56b5..27c5ef9b1763 100644
> --- a/drivers/net/mlx5/mlx5.c
> +++ b/drivers/net/mlx5/mlx5.c
> @@ -1105,6 +1105,7 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
>  	int own_domain_id = 0;
>  	uint16_t port_id;
>  	unsigned int i;
> +	char ifname[IF_NAMESIZE];
> 
>  	/* Determine if this port representor is supposed to be spawned. */
>  	if (switch_info->representor && dpdk_dev->devargs) { @@ -1479,18
> +1480,16 @@ mlx5_dev_spawn(struct rte_device *dpdk_dev,
>  		mac.addr_bytes[0], mac.addr_bytes[1],
>  		mac.addr_bytes[2], mac.addr_bytes[3],
>  		mac.addr_bytes[4], mac.addr_bytes[5]); -#ifndef NDEBUG
> -	{
> -		char ifname[IF_NAMESIZE];
> 
> -		if (mlx5_get_ifname(eth_dev, &ifname) == 0)
> -			DRV_LOG(DEBUG, "port %u ifname is \"%s\"",

> +	if (mlx5_get_ifname(eth_dev, &ifname) == 0) {
> +		priv->if_index = if_nametoindex(ifname);
> +		DRV_LOG(DEBUG, "port %u ifname is \"%s\"",
>  				eth_dev->data->port_id, ifname);
> -		else
> -			DRV_LOG(DEBUG, "port %u ifname is unknown",
> -				eth_dev->data->port_id);
> +	} else {
> +		DRV_LOG(DEBUG, "port %u ifname is unknown",
> +			eth_dev->data->port_id);
>  	}
> -#endif
> +
>  	/* Get actual MTU if possible. */
>  	err = mlx5_get_mtu(eth_dev, &priv->mtu);
>  	if (err) {
> diff --git a/drivers/net/mlx5/mlx5.h b/drivers/net/mlx5/mlx5.h index
> 5af3f413cdcb..a06ffd444255 100644
> --- a/drivers/net/mlx5/mlx5.h
> +++ b/drivers/net/mlx5/mlx5.h
> @@ -342,6 +342,7 @@ struct mlx5_priv {
>  	uint16_t vlan_filter[MLX5_MAX_VLAN_IDS]; /* VLAN filters table. */
>  	unsigned int vlan_filter_n; /* Number of configured VLAN filters. */
>  	/* Device properties. */
> +	unsigned int if_index; /* Associated kernel network device index. */
>  	uint16_t mtu; /* Configured MTU. */
>  	unsigned int isolated:1; /* Whether isolated mode is enabled. */
>  	unsigned int representor:1; /* Device is a port representor. */ diff --
> git a/drivers/net/mlx5/mlx5_ethdev.c b/drivers/net/mlx5/mlx5_ethdev.c
> index eeefe4df3cd4..41e58db5e573 100644
> --- a/drivers/net/mlx5/mlx5_ethdev.c
> +++ b/drivers/net/mlx5/mlx5_ethdev.c
> @@ -605,7 +605,6 @@ mlx5_dev_infos_get(struct rte_eth_dev *dev, struct
> rte_eth_dev_info *info)
>  	struct mlx5_priv *priv = dev->data->dev_private;
>  	struct mlx5_dev_config *config = &priv->config;
>  	unsigned int max;
> -	char ifname[IF_NAMESIZE];
> 
>  	/* FIXME: we should ask the device for these values. */
>  	info->min_rx_bufsize = 32;
> @@ -626,8 +625,7 @@ mlx5_dev_infos_get(struct rte_eth_dev *dev, struct
> rte_eth_dev_info *info)
>  	info->rx_offload_capa = (mlx5_get_rx_port_offloads() |
>  				 info->rx_queue_offload_capa);
>  	info->tx_offload_capa = mlx5_get_tx_port_offloads(dev);
> -	if (mlx5_get_ifname(dev, &ifname) == 0)
> -		info->if_index = if_nametoindex(ifname);
> +	info->if_index = priv->if_index;
>  	info->reta_size = priv->reta_idx_n ?
>  		priv->reta_idx_n : config->ind_table_max_size;
>  	info->hash_key_size = MLX5_RSS_HASH_KEY_LEN;
> --
> 2.20.1