From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx3-rdu2.redhat.com ([66.187.233.73]:54000 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751738AbeBTNcL (ORCPT ); Tue, 20 Feb 2018 08:32:11 -0500 Subject: [net PATCH 2/4] virtio_net: fix XDP code path in receive_small() From: Jesper Dangaard Brouer To: Jason Wang Cc: "Michael S. Tsirkin" , netdev@vger.kernel.org, John Fastabend , Alexei Starovoitov , Saeed Mahameed , Jesper Dangaard Brouer , Daniel Borkmann , "David S. Miller" , Tariq Toukan Date: Tue, 20 Feb 2018 14:32:10 +0100 Message-ID: <151913352995.28247.4449049695120368682.stgit@firesoul> In-Reply-To: <151913348634.28247.17519468037896960567.stgit@firesoul> References: <151913348634.28247.17519468037896960567.stgit@firesoul> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org List-ID: When configuring virtio_net to use the code path 'receive_small()', in-order to get correct XDP_REDIRECT support, I discovered TCP packets would get silently dropped when loading an XDP program action XDP_PASS. The bug seems to be that receive_small() when XDP is loaded check that hdr->hdr.flags is zero, which seems wrong as hdr.flags contains the flags VIRTIO_NET_HDR_F_* : #define VIRTIO_NET_HDR_F_NEEDS_CSUM 1 /* Use csum_start, csum_offset */ #define VIRTIO_NET_HDR_F_DATA_VALID 2 /* Csum is valid */ TCP got dropped as it had the VIRTIO_NET_HDR_F_DATA_VALID flag set. The flags that are relevant here are the VIRTIO_NET_HDR_GSO_* flags stored in hdr->hdr.gso_type. Thus, the fix is just check that none of the gso_type flags have been set. Fixes: bb91accf2733 ("virtio-net: XDP support for small buffers") Signed-off-by: Jesper Dangaard Brouer --- drivers/net/virtio_net.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 0ca91942a884..10c8fc46b588 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -558,7 +558,7 @@ static struct sk_buff *receive_small(struct net_device *dev, void *orig_data; u32 act; - if (unlikely(hdr->hdr.gso_type || hdr->hdr.flags)) + if (unlikely(hdr->hdr.gso_type)) goto err_xdp; if (unlikely(xdp_headroom < virtnet_get_headroom(vi))) {