Commit c6c1f11b authored Apr 13, 2022 by Björn Töpel Committed by Daniel Borkmann Apr 15, 2022

xsk: Improve xdp_do_redirect() error codes



The error codes returned by xdp_do_redirect() when redirecting a frame
to an AF_XDP socket has not been very useful. A driver could not
distinguish between different errors. Prior this change the following
codes where used:

Socket not bound or incorrect queue/netdev: EINVAL
XDP frame/AF_XDP buffer size mismatch: ENOSPC
Could not allocate buffer (copy mode): ENOSPC
AF_XDP Rx buffer full: ENOSPC

After this change:

Socket not bound or incorrect queue/netdev: EINVAL
XDP frame/AF_XDP buffer size mismatch: ENOSPC
Could not allocate buffer (copy mode): ENOMEM
AF_XDP Rx buffer full: ENOBUFS

An AF_XDP zero-copy driver can now potentially determine if the
failure was due to a full Rx buffer, and if so stop processing more
frames, yielding to the userland AF_XDP application.

Signed-off-by: Björn Töpel <bjorn@kernel.org>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/20220413153015.453864-2-maciej.fijalkowski@intel.com

parent 241d50ec

net/xdp/xsk.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -184,7 +184,7 @@ static int __xsk_rcv(struct xdp_sock xs, struct xdp_buff xdp)
		xsk_xdp = xsk_buff_alloc(xs->pool);
		if (!xsk_xdp) {
		xs->rx_dropped++;
		return -ENOSPC;
		return -ENOMEM;
		}

		xsk_copy_xdp(xsk_xdp, xdp, len);

net/xdp/xsk_queue.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -382,7 +382,7 @@ static inline int xskq_prod_reserve_desc(struct xsk_queue *q,
		u32 idx;

		if (xskq_prod_is_full(q))
		return -ENOSPC;
		return -ENOBUFS;

		/* A, matches D */
		idx = q->cached_prod++ & q->ring_mask;