netdev - [PATCH v2 bpf-next 02/14] xsk: diversify return codes in xsk_rcv

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Date:   Wed, 13 Apr 2022 17:30:03 +0200
From:   Maciej Fijalkowski <maciej.fijalkowski@...el.com>
To:     bpf@...r.kernel.org, ast@...nel.org, daniel@...earbox.net
Cc:     netdev@...r.kernel.org, magnus.karlsson@...el.com,
        alexandr.lobakin@...el.com, maximmi@...dia.com, kuba@...nel.org,
        bjorn@...nel.org,
        Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>
Subject: [PATCH v2 bpf-next 02/14] xsk: diversify return codes in xsk_rcv_check()

Inspired by patch that made xdp_do_redirect() return values for XSKMAP
more meaningful, return -ENXIO instead of -EINVAL for socket being
unbound in xsk_rcv_check() as this is the usual value that is returned
for such event. In turn, it is now possible to easily distinguish what
went wrong, which is a bit harder when for both cases checked, -EINVAL
was returned.

Return codes can be counted in a nice way via bpftrace oneliner that
Jesper has shown:

bpftrace -e 'tracepoint:xdp:xdp_redirect* {@err[-args->err] = count();}'

Acked-by: Jesper Dangaard Brouer <brouer@...hat.com>
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
---
 net/xdp/xsk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index f75e121073e7..040c73345b7c 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -217,7 +217,7 @@ static bool xsk_is_bound(struct xdp_sock *xs)
 static int xsk_rcv_check(struct xdp_sock *xs, struct xdp_buff *xdp)
 {
 	if (!xsk_is_bound(xs))
-		return -EINVAL;
+		return -ENXIO;
 
 	if (xs->dev != xdp->rxq->dev || xs->queue_id != xdp->rxq->queue_index)
 		return -EINVAL;
-- 
2.33.1