On Fri, Feb 13, 2026 at 05:04:03AM +0100, Loktionov, Aleksandr wrote:
>
>
> > -----Original Message-----
> > From: Zaremba, Larysa <[email protected]>
> > Sent: Thursday, February 12, 2026 7:33 PM
> > To: [email protected]
> > Cc: Zaremba, Larysa <[email protected]>; Claudiu Manoil
> > <[email protected]>; Vladimir Oltean <[email protected]>;
> > Wei Fang <[email protected]>; Clark Wang <[email protected]>;
> > Andrew Lunn <[email protected]>; David S. Miller
> > <[email protected]>; Eric Dumazet <[email protected]>; Jakub
> > Kicinski <[email protected]>; Paolo Abeni <[email protected]>; Nguyen,
> > Anthony L <[email protected]>; Kitszel, Przemyslaw
> > <[email protected]>; Alexei Starovoitov <[email protected]>;
> > Daniel Borkmann <[email protected]>; Jesper Dangaard Brouer
> > <[email protected]>; John Fastabend <[email protected]>;
> > Stanislav Fomichev <[email protected]>; Andrii Nakryiko
> > <[email protected]>; Martin KaFai Lau <[email protected]>; Eduard
> > Zingerman <[email protected]>; Song Liu <[email protected]>; Yonghong
> > Song <[email protected]>; KP Singh <[email protected]>; Hao
> > Luo <[email protected]>; Jiri Olsa <[email protected]>; Simon Horman
> > <[email protected]>; Shuah Khan <[email protected]>; Lobakin,
> > Aleksander <[email protected]>; Fijalkowski, Maciej
> > <[email protected]>; Bastien Curutchet (eBPF Foundation)
> > <[email protected]>; Vyavahare, Tushar
> > <[email protected]>; Jason Xing <[email protected]>;
> > Ricardo B. Marlière <[email protected]>; Eelco Chaudron
> > <[email protected]>; Lorenzo Bianconi <[email protected]>; Toke
> > Hoiland-Jorgensen <[email protected]>; [email protected];
> > [email protected]; [email protected]; intel-wired-
> > [email protected]; [email protected]; Loktionov,
> > Aleksandr <[email protected]>; Dragos Tatulea
> > <[email protected]>
> > Subject: [PATCH bpf v2 6/9] i40e: use xdp.frame_sz as XDP RxQ info
> > frag_size
> >
> > The only user of frag_size field in XDP RxQ info is
> > bpf_xdp_frags_increase_tail(). It clearly expects whole buffer size
> > instead of DMA write size. Different assumptions in i40e driver
> > configuration lead to negative tailroom.
> >
> > Set frag_size to the same value as frame_sz in shared pages mode,
> > use new helper to set frag_size when AF_XDP ZC is active.
> >
> > Fixes: a045d2f2d03d ("i40e: set xdp_rxq_info::frag_size")
> > Reviewed-by: Aleksandr Loktionov <[email protected]>
> > Signed-off-by: Larysa Zaremba <[email protected]>
> > ---
> > drivers/net/ethernet/intel/i40e/i40e_main.c | 9 ++++++---
> > 1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c
> > b/drivers/net/ethernet/intel/i40e/i40e_main.c
> > index eaa5b65e6daf..f91157774f1d 100644
> > --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> > +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> > @@ -3563,6 +3563,7 @@ static int i40e_configure_rx_ring(struct
> > i40e_ring *ring)
> > u16 pf_q = vsi->base_queue + ring->queue_index;
> > struct i40e_hw *hw = &vsi->back->hw;
> > struct i40e_hmc_obj_rxq rx_ctx;
> > + u32 xdp_frame_sz = 0;
> > int err = 0;
> > bool ok;
> >
> https://elixir.bootlin.com/linux/v6.19-rc5/source/drivers/net/ethernet/intel/i40e/i40e_main.c#L3577
> All VSIs except main will be skipped, so xdp_init_buff() will be called with
> the default xdp_frame_sz = 0;
> Is it ok?
Sorry, you forgot to remove your Reviewed-by(s), patch changed too much.
You are right, xdp_frame_sz should be (i40e_rx_pg_size(ring) / 2) for non-main
VSIs. I assumed that they do not need xdp_buff, but it is unescapable in
non-XDP
Rx processing after XDP mbuf introduction.
>
> > @@ -3579,11 +3580,12 @@ static int i40e_configure_rx_ring(struct
> > i40e_ring *ring)
> >
> > ring->xsk_pool = i40e_xsk_pool(ring);
> > if (ring->xsk_pool) {
> > + xdp_frame_sz = xsk_pool_get_rx_frag_step(ring-
> > >xsk_pool);
> > ring->rx_buf_len = xsk_pool_get_rx_frame_size(ring-
> > >xsk_pool);
> > err = __xdp_rxq_info_reg(&ring->xdp_rxq, ring->netdev,
> > ring->queue_index,
> > ring->q_vector->napi.napi_id,
> > - ring->rx_buf_len);
> > + xdp_frame_sz);
> > if (err)
> > return err;
> > err = xdp_rxq_info_reg_mem_model(&ring->xdp_rxq,
> > @@ -3596,10 +3598,11 @@ static int i40e_configure_rx_ring(struct
> > i40e_ring *ring)
> > ring->queue_index);
> >
> > } else {
> > + xdp_frame_sz = i40e_rx_pg_size(ring) / 2;
> > err = __xdp_rxq_info_reg(&ring->xdp_rxq, ring->netdev,
> > ring->queue_index,
> > ring->q_vector->napi.napi_id,
> > - ring->rx_buf_len);
> > + xdp_frame_sz);
> > if (err)
> > return err;
> > err = xdp_rxq_info_reg_mem_model(&ring->xdp_rxq,
> > @@ -3610,7 +3613,7 @@ static int i40e_configure_rx_ring(struct
> > i40e_ring *ring)
> > }
> >
> > skip:
> > - xdp_init_buff(&ring->xdp, i40e_rx_pg_size(ring) / 2, &ring-
> > >xdp_rxq);
> > + xdp_init_buff(&ring->xdp, xdp_frame_sz, &ring->xdp_rxq);
> >
> > rx_ctx.dbuff = DIV_ROUND_UP(ring->rx_buf_len,
> > BIT_ULL(I40E_RXQ_CTX_DBUFF_SHIFT));
> > --
> > 2.52.0
>
