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io_uring/zcrx: don't set rx_page_size when not requested

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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.

Fixes: 795663b4d1 ("io_uring/zcrx: implement large rx buffer support")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jakub Kicinski 2026-02-27 09:07:45 -08:00 • committed by Jens Axboe
parent 85f6c439a6
commit 3d17d76d1f
1 changed files with 2 additions and 1 deletions
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3
io_uring/zcrx.c
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@ -837,7 +837,8 @@ int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
if (ret)
goto netdev_put_unlock;
mp_param.rx_page_size = 1U << ifq->niov_shift;
if (reg.rx_buf_len)
mp_param.rx_page_size = 1U << ifq->niov_shift;
mp_param.mp_ops = &io_uring_pp_zc_ops;
mp_param.mp_priv = ifq;
ret = __net_mp_open_rxq(ifq->netdev, reg.if_rxq, &mp_param, NULL);