From f7387d6579d65efd490a864254101cb665f2e7a7 Mon Sep 17 00:00:00 2001 From: "Nikhil P. Rao" Date: Wed, 25 Feb 2026 00:00:27 +0000 Subject: [PATCH] xsk: Fix zero-copy AF_XDP fragment drop AF_XDP should ensure that only a complete packet is sent to application. In the zero-copy case, if the Rx queue gets full as fragments are being enqueued, the remaining fragments are dropped. For the multi-buffer case, add a check to ensure that the Rx queue has enough space for all fragments of a packet before starting to enqueue them. Fixes: 24ea50127ecf ("xsk: support mbuf on ZC RX") Signed-off-by: Nikhil P. Rao Link: https://patch.msgid.link/20260225000456.107806-3-nikhil.rao@amd.com Signed-off-by: Jakub Kicinski --- net/xdp/xsk.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index be882a8d473c..6149f6a79897 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -167,25 +167,31 @@ static int xsk_rcv_zc(struct xdp_sock *xs, struct xdp_buff *xdp, u32 len) struct xdp_buff_xsk *pos, *tmp; struct list_head *xskb_list; u32 contd = 0; + u32 num_desc; int err; - if (frags) - contd = XDP_PKT_CONTD; - - err = __xsk_rcv_zc(xs, xskb, len, contd); - if (err) - goto err; - if (likely(!frags)) + if (likely(!frags)) { + err = __xsk_rcv_zc(xs, xskb, len, contd); + if (err) + goto err; return 0; + } + contd = XDP_PKT_CONTD; + num_desc = xdp_get_shared_info_from_buff(xdp)->nr_frags + 1; + if (xskq_prod_nb_free(xs->rx, num_desc) < num_desc) { + xs->rx_queue_full++; + err = -ENOBUFS; + goto err; + } + + __xsk_rcv_zc(xs, xskb, len, contd); xskb_list = &xskb->pool->xskb_list; list_for_each_entry_safe(pos, tmp, xskb_list, list_node) { if (list_is_singular(xskb_list)) contd = 0; len = pos->xdp.data_end - pos->xdp.data; - err = __xsk_rcv_zc(xs, pos, len, contd); - if (err) - goto err; + __xsk_rcv_zc(xs, pos, len, contd); list_del_init(&pos->list_node); }