RE: [PATCH bpf v3 2/9] xsk: introduce helper to determine rxq->frag_size

[Loktionov, Aleksandr]

> -----Original Message-----
> From: Zaremba, Larysa <larysa.zaremba@xxxxxxxxx>
> Sent: Tuesday, February 17, 2026 2:25 PM
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> Subject: [PATCH bpf v3 2/9] xsk: introduce helper to determine rxq-
> >frag_size
> 
> rxq->frag_size is basically a step between consecutive strictly
> aligned
> frames. In ZC mode, chunk size fits exactly, but if chunks are
> unaligned, there is no safe way to determine accessible space to grow
> tailroom.
> 
> Report frag_size to be zero, if chunks are unaligned, chunk_size
> otherwise.
> 
> Fixes: 24ea50127ecf ("xsk: support mbuf on ZC RX")
> Signed-off-by: Larysa Zaremba <larysa.zaremba@xxxxxxxxx>
> ---
>  include/net/xdp_sock_drv.h | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/include/net/xdp_sock_drv.h b/include/net/xdp_sock_drv.h
> index 242e34f771cc..09d972f4bd60 100644
> --- a/include/net/xdp_sock_drv.h
> +++ b/include/net/xdp_sock_drv.h
> @@ -51,6 +51,11 @@ static inline u32 xsk_pool_get_rx_frame_size(struct
> xsk_buff_pool *pool)
>  	return xsk_pool_get_chunk_size(pool) -
> xsk_pool_get_headroom(pool);  }
> 
> +static inline u32 xsk_pool_get_rx_frag_step(struct xsk_buff_pool
> *pool)
> +{
> +	return pool->unaligned ? 0 : xsk_pool_get_chunk_size(pool); }
> +
>  static inline void xsk_pool_set_rxq_info(struct xsk_buff_pool *pool,
>  					 struct xdp_rxq_info *rxq)
>  {
> @@ -337,6 +342,11 @@ static inline u32
> xsk_pool_get_rx_frame_size(struct xsk_buff_pool *pool)
>  	return 0;
>  }
> 
> +static inline u32 xsk_pool_get_rx_frag_step(struct xsk_buff_pool
> *pool)
> +{
> +	return 0;
> +}
> +
>  static inline void xsk_pool_set_rxq_info(struct xsk_buff_pool *pool,
>  					 struct xdp_rxq_info *rxq)
>  {
> --
> 2.52.0

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@xxxxxxxxx>