netdev - Re: [PATCH net-next V2 09/11] net/mlx5e: Add support for UNREADABLE netmem page pools

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Message-ID: <CAHS8izOwPVSKQJBSOjmtfXfA6ZBHVqvWRV=WSYM41XXninsSSw@mail.gmail.com>
Date: Thu, 22 May 2025 16:26:33 -0700
From: Mina Almasry <almasrymina@...gle.com>
To: Tariq Toukan <tariqt@...dia.com>
Cc: "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>, Eric Dumazet <edumazet@...gle.com>, 
	Andrew Lunn <andrew+netdev@...n.ch>, Saeed Mahameed <saeedm@...dia.com>, 
	Leon Romanovsky <leon@...nel.org>, Richard Cochran <richardcochran@...il.com>, 
	Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	Jesper Dangaard Brouer <hawk@...nel.org>, John Fastabend <john.fastabend@...il.com>, netdev@...r.kernel.org, 
	linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org, bpf@...r.kernel.org, 
	Moshe Shemesh <moshe@...dia.com>, Mark Bloch <mbloch@...dia.com>, Gal Pressman <gal@...dia.com>, 
	Cosmin Ratiu <cratiu@...dia.com>, Dragos Tatulea <dtatulea@...dia.com>
Subject: Re: [PATCH net-next V2 09/11] net/mlx5e: Add support for UNREADABLE
 netmem page pools

On Thu, May 22, 2025 at 2:46 PM Tariq Toukan <tariqt@...dia.com> wrote:
>
> From: Saeed Mahameed <saeedm@...dia.com>
>
> On netdev_rx_queue_restart, a special type of page pool maybe expected.
>
> In this patch declare support for UNREADABLE netmem iov pages in the
> pool params only when header data split shampo RQ mode is enabled, also
> set the queue index in the page pool params struct.
>
> Shampo mode requirement: Without header split rx needs to peek at the data,
> we can't do UNREADABLE_NETMEM.
>
> Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
> Reviewed-by: Dragos Tatulea <dtatulea@...dia.com>
> Signed-off-by: Cosmin Ratiu <cratiu@...dia.com>
> Signed-off-by: Tariq Toukan <tariqt@...dia.com>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> index 9e2975782a82..485b1515ace5 100644
> --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
> @@ -952,6 +952,11 @@ static int mlx5e_alloc_rq(struct mlx5e_params *params,
>                 pp_params.netdev    = rq->netdev;
>                 pp_params.dma_dir   = rq->buff.map_dir;
>                 pp_params.max_len   = PAGE_SIZE;
> +               pp_params.queue_idx = rq->ix;
> +
> +               /* Shampo header data split allow for unreadable netmem */
> +               if (test_bit(MLX5E_RQ_STATE_SHAMPO, &rq->state))
> +                       pp_params.flags |= PP_FLAG_ALLOW_UNREADABLE_NETMEM;
>

This patch itself looks good to me for FWIW, but unreadable netmem
will return netmem_address(netmem) == NULL, which from an initial look
didn't seem like you were handling in the previous patches. Not sure
if oversight or you are sure you're not going to have unreadable
netmem in these code paths for some reason.


-- 
Thanks,
Mina