netdev - [V2 PATCH net-next 3/5] ixgbe: use return codes from ndo_xdp

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Message-ID: <150348333019.23476.13227771885092232782.stgit@firesoul>
Date:   Wed, 23 Aug 2017 12:15:30 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     netdev@...r.kernel.org
Cc:     Daniel Borkmann <borkmann@...earbox.net>,
        John Fastabend <john.fastabend@...il.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>
Subject: [V2 PATCH net-next 3/5] ixgbe: use return codes from ndo_xdp_xmit
 that are distinguishable

For XDP_REDIRECT the use of return code -EINVAL is confusing, as it is
used in three different cases.  (1) When the index or ifindex lookup
fails, and in the ixgbe driver (2) when link is down and (3) when XDP
have not been enabled.

The return code can be picked up by the tracepoint xdp:xdp_redirect
for diagnosing why XDP_REDIRECT isn't working.  Thus, there is a need
different return codes to tell the issues apart.

I'm considering using a specific err-code scheme for XDP_REDIRECT
instead of using these errno codes.

Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>
Acked-by: Daniel Borkmann <daniel@...earbox.net>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 8d3224ad6434..3afb8c4b9d48 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -9849,14 +9849,14 @@ static int ixgbe_xdp_xmit(struct net_device *dev, struct xdp_buff *xdp)
 	int err;
 
 	if (unlikely(test_bit(__IXGBE_DOWN, &adapter->state)))
-		return -EINVAL;
+		return -ENOLINK;
 
 	/* During program transitions its possible adapter->xdp_prog is assigned
 	 * but ring has not been configured yet. In this case simply abort xmit.
 	 */
 	ring = adapter->xdp_prog ? adapter->xdp_ring[smp_processor_id()] : NULL;
 	if (unlikely(!ring))
-		return -EINVAL;
+		return -ENXIO;
 
 	err = ixgbe_xmit_xdp_ring(adapter, xdp);
 	if (err != IXGBE_XDP_TX)