netdev - Re: [PATCH net v2 2/2] mlx4: xdp_prog becomes inactive after ethtool '-L' or '-G'

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Date:   Thu, 2 Feb 2017 19:13:30 +0200
From:   Tariq Toukan <tariqt@...lanox.com>
To:     Martin KaFai Lau <kafai@...com>, <netdev@...r.kernel.org>
CC:     Saeed Mahameed <saeedm@...lanox.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Kernel Team <kernel-team@...com>,
        Brenden Blanco <bblanco@...mgrid.com>
Subject: Re: [PATCH net v2 2/2] mlx4: xdp_prog becomes inactive after ethtool
 '-L' or '-G'


On 01/02/2017 8:35 AM, Martin KaFai Lau wrote:
> After calling mlx4_en_try_alloc_resources (e.g. by changing the
> number of rx-queues with ethtool -L), the existing xdp_prog becomes
> inactive.
>
> The bug is that the xdp_prog ptr has not been carried over from
> the old rx-queues to the new rx-queues
>
> Fixes: 47a38e155037 ("net/mlx4_en: add support for fast rx drop bpf program")
> Cc: Brenden Blanco <bblanco@...mgrid.com>
> Cc: Saeed Mahameed <saeedm@...lanox.com>
> Cc: Tariq Toukan <tariqt@...lanox.com>
> Signed-off-by: Martin KaFai Lau <kafai@...com>
> ---
>   drivers/net/ethernet/mellanox/mlx4/en_ethtool.c |  4 ++--
>   drivers/net/ethernet/mellanox/mlx4/en_netdev.c  | 27 +++++++++++++++++++++----
>   drivers/net/ethernet/mellanox/mlx4/mlx4_en.h    |  3 ++-
>   3 files changed, 27 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c
> index d5a9372ed84d..9aa422691954 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_ethtool.c
> @@ -1099,7 +1099,7 @@ static int mlx4_en_set_ringparam(struct net_device *dev,
>   	memcpy(&new_prof, priv->prof, sizeof(struct mlx4_en_port_profile));
>   	new_prof.tx_ring_size = tx_size;
>   	new_prof.rx_ring_size = rx_size;
> -	err = mlx4_en_try_alloc_resources(priv, tmp, &new_prof);
> +	err = mlx4_en_try_alloc_resources(priv, tmp, &new_prof, true);
>   	if (err)
>   		goto out;
>   
> @@ -1774,7 +1774,7 @@ static int mlx4_en_set_channels(struct net_device *dev,
>   	new_prof.tx_ring_num[TX_XDP] = xdp_count;
>   	new_prof.rx_ring_num = channel->rx_count;
>   
> -	err = mlx4_en_try_alloc_resources(priv, tmp, &new_prof);
> +	err = mlx4_en_try_alloc_resources(priv, tmp, &new_prof, true);
>   	if (err)
>   		goto out;
>   
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> index 3abcead208d2..3b4961a8e8e4 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> @@ -2186,9 +2186,11 @@ static void mlx4_en_update_priv(struct mlx4_en_priv *dst,
>   
>   int mlx4_en_try_alloc_resources(struct mlx4_en_priv *priv,
>   				struct mlx4_en_priv *tmp,
> -				struct mlx4_en_port_profile *prof)
> +				struct mlx4_en_port_profile *prof,
> +				bool carry_xdp_prog)
>   {
> -	int t;
> +	struct bpf_prog *xdp_prog;
> +	int i, t;
>   
>   	mlx4_en_copy_priv(tmp, priv, prof);
>   
> @@ -2202,6 +2204,23 @@ int mlx4_en_try_alloc_resources(struct mlx4_en_priv *priv,
>   		}
>   		return -ENOMEM;
>   	}
> +
> +	/* All rx_rings has the same xdp_prog.  Pick the first one. */
> +	xdp_prog = rcu_dereference_protected(
> +		priv->rx_ring[0]->xdp_prog,
> +		lockdep_is_held(&priv->mdev->state_lock));
> +
> +	if (xdp_prog && carry_xdp_prog) {
> +		xdp_prog = bpf_prog_add(xdp_prog, tmp->rx_ring_num);
> +		if (IS_ERR(xdp_prog)) {
> +			mlx4_en_free_resources(tmp);
> +			return PTR_ERR(xdp_prog);
> +		}
> +		for (i = 0; i < tmp->rx_ring_num; i++)
> +			rcu_assign_pointer(tmp->rx_ring[i]->xdp_prog,
> +					   xdp_prog);
> +	}
> +
>   	return 0;
>   }
>   
> @@ -2751,7 +2770,7 @@ static int mlx4_xdp_set(struct net_device *dev, struct bpf_prog *prog)
>   		en_warn(priv, "Reducing the number of TX rings, to not exceed the max total rings number.\n");
>   	}
>   
> -	err = mlx4_en_try_alloc_resources(priv, tmp, &new_prof);
> +	err = mlx4_en_try_alloc_resources(priv, tmp, &new_prof, false);
>   	if (err) {
>   		if (prog)
>   			bpf_prog_sub(prog, priv->rx_ring_num - 1);
> @@ -3495,7 +3514,7 @@ int mlx4_en_reset_config(struct net_device *dev,
>   	memcpy(&new_prof, priv->prof, sizeof(struct mlx4_en_port_profile));
>   	memcpy(&new_prof.hwtstamp_config, &ts_config, sizeof(ts_config));
>   
> -	err = mlx4_en_try_alloc_resources(priv, tmp, &new_prof);
> +	err = mlx4_en_try_alloc_resources(priv, tmp, &new_prof, true);
>   	if (err)
>   		goto out;
>   
> diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> index ba1c6cd0cc79..cec59bc264c9 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> +++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> @@ -679,7 +679,8 @@ void mlx4_en_set_stats_bitmap(struct mlx4_dev *dev,
>   
>   int mlx4_en_try_alloc_resources(struct mlx4_en_priv *priv,
>   				struct mlx4_en_priv *tmp,
> -				struct mlx4_en_port_profile *prof);
> +				struct mlx4_en_port_profile *prof,
> +				bool carry_xdp_prog);
>   void mlx4_en_safe_replace_resources(struct mlx4_en_priv *priv,
>   				    struct mlx4_en_priv *tmp);
>   
Reviewed-by: Tariq Toukan <tariqt@...lanox.com>

Thanks.