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

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 2c34caee0fd115b099a5de5f5c43537214fa73bb..f75e121073e7ba56ecc76c6df0956fbd898b1338 100644 (file)
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -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);

diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 801cda5d19381292d5282c10f0ea763aa5b630da..644479e65578c94067f3a6f19153dcab8d5a9bd1 100644 (file)
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -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;