Re: [PATCH iouring] io_uring/zcrx: don't set rx_page_size when not requested

[Pavel Begunkov <asml.silence@gmail.com>]

On 2/27/26 17:07, Jakub Kicinski wrote:
> The rx_buf_len parameter was recently added to the Rx zero-copy
> implementation. The expectation is that when not set system will
> maintain previous behavior and use the default buffer size (PAGE_SIZE).
> 
> This works correctly at the iouring level, but we don't preserve
> the same "zero means default" semantics when registering the memory
> provider on the netdev. mp_param.rx_page_size is unconditionally
> set to PAGE_SIZE. This causes __net_mp_open_rxq() to check for
> QCFG_RX_PAGE_SIZE support in the driver, and return -EOPNOTSUPP
> for drivers that don't advertise it -- even though the user never
> asked for large buffers.
> 
> Only set mp_param.rx_page_size when rx_buf_len was explicitly provided,
> so that the default page size path works on all zcrx-capable drivers.
> mlx5 and fbnic only support 4kB pages in the current release.

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>

Jens, can you take it into io_uring-7.0?

-- 
Pavel Begunkov