[PATCH net v4 2/2] xsk: Fix zero-copy AF_XDP fragment drop
From: Nikhil P. Rao <hidden>
Date: 2026-02-17 21:11:01
Subsystem:
networking [general], the rest, xdp sockets (af_xdp) · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, Magnus Karlsson, Maciej Fijalkowski
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")
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Nikhil P. Rao <redacted>
---
net/xdp/xsk.c | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index f2ec4f78bbb6..f7f816a5cb80 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c@@ -167,25 +167,32 @@ 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) + if (frags) { + num_desc = xdp_get_shared_info_from_buff(xdp)->nr_frags + 1; contd = XDP_PKT_CONTD; + } else { + err = __xsk_rcv_zc(xs, xskb, len, contd); + if (err) + goto err; + return 0; + } - err = __xsk_rcv_zc(xs, xskb, len, contd); - if (err) + if (xskq_prod_nb_free(xs->rx, num_desc) < num_desc) { + xs->rx_queue_full++; + err = -ENOBUFS; goto err; - if (likely(!frags)) - return 0; + } + __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); }
--
2.43.0