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Message-ID: <25a72690-6cae-bc7b-b30c-a0ece4fa0393@gmail.com>
Date: Thu, 26 Jan 2023 22:41:30 +0200
From: Tariq Toukan <ttoukan.linux@...il.com>
To: Maxim Mikityanskiy <maxtram95@...il.com>, netdev@...r.kernel.org,
Saeed Mahameed <saeedm@...dia.com>
Cc: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, Gal Pressman <gal@...dia.com>,
Tariq Toukan <tariqt@...dia.com>
Subject: Re: [PATCH net 1/2] net/mlx5e: XDP, Allow growing tail for XDP multi
buffer
On 26/01/2023 21:10, Maxim Mikityanskiy wrote:
> The cited commits missed passing frag_size to __xdp_rxq_info_reg, which
> is required by bpf_xdp_adjust_tail to support growing the tail pointer
> in fragmented packets. Pass the missing parameter when the current RQ
> mode allows XDP multi buffer.
>
> Fixes: ea5d49bdae8b ("net/mlx5e: Add XDP multi buffer support to the non-linear legacy RQ")
> Fixes: 9cb9482ef10e ("net/mlx5e: Use fragments of the same size in non-linear legacy RQ with XDP")
> Signed-off-by: Maxim Mikityanskiy <maxtram95@...il.com>
> Cc: Tariq Toukan <tariqt@...dia.com>
> ---
> drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> index abcc614b6191..cdd1e47e18f9 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> @@ -576,9 +576,10 @@ static void mlx5e_free_mpwqe_rq_drop_page(struct mlx5e_rq *rq)
> }
>
> static int mlx5e_init_rxq_rq(struct mlx5e_channel *c, struct mlx5e_params *params,
> - struct mlx5e_rq *rq)
> + struct mlx5e_rq_param *rq_params, struct mlx5e_rq *rq)
> {
> struct mlx5_core_dev *mdev = c->mdev;
> + u32 xdp_frag_size = 0;
> int err;
>
> rq->wq_type = params->rq_wq_type;
> @@ -599,7 +600,11 @@ static int mlx5e_init_rxq_rq(struct mlx5e_channel *c, struct mlx5e_params *param
> if (err)
> return err;
>
> - return xdp_rxq_info_reg(&rq->xdp_rxq, rq->netdev, rq->ix, c->napi.napi_id);
> + if (rq->wq_type == MLX5_WQ_TYPE_CYCLIC && rq_params->frags_info.num_frags > 1)
How about a more generic check? like:
if (params->xdp_prog && params->xdp_prog->aux->xdp_has_frags)
So we won't have to maintain this when Stridng RQ support is added.
> + xdp_frag_size = rq_params->frags_info.arr[1].frag_stride;
Again, in order to not maintain this (frags_info.arr[1].frag_stride not
relevant for Striding RQ), isn't the value always PAGE_SIZE?
Another idea is to introduce something like
#define XDP_MB_FRAG_SZ (PAGE_SIZE)
use it here and in mlx5e_build_rq_frags_info ::
if (byte_count > max_mtu || params->xdp_prog) {
frag_size_max = XDP_MB_FRAG_SZ;
Not sure it's worth it...
Both ways we save passing rq_params in the callstack.
> +
> + return __xdp_rxq_info_reg(&rq->xdp_rxq, rq->netdev, rq->ix, c->napi.napi_id,
> + xdp_frag_size);
> }
>
> static int mlx5_rq_shampo_alloc(struct mlx5_core_dev *mdev,
> @@ -2214,7 +2219,7 @@ static int mlx5e_open_rxq_rq(struct mlx5e_channel *c, struct mlx5e_params *param
> {
> int err;
>
> - err = mlx5e_init_rxq_rq(c, params, &c->rq);
> + err = mlx5e_init_rxq_rq(c, params, rq_params, &c->rq);
> if (err)
> return err;
>
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