linux-kernel - [PATCH 4.9 16/51] virtio: dont set VIRTIO_NET_HDR_F_DATA

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Date:   Thu,  2 Feb 2017 19:37:35 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Rolf Neugebauer <rolf.neugebauer@...ker.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.9 16/51] virtio: dont set VIRTIO_NET_HDR_F_DATA_VALID on xmit

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Rolf Neugebauer <rolf.neugebauer@...ker.com>


[ Upstream commit 501db511397fd6efff3aa5b4e8de415b55559550 ]

This patch part reverts fd2a0437dc33 and e858fae2b0b8 which introduced a
subtle change in how the virtio_net flags are derived from the SKBs
ip_summed field.

With the above commits, the flags are set to VIRTIO_NET_HDR_F_DATA_VALID
when ip_summed == CHECKSUM_UNNECESSARY, thus treating it differently to
ip_summed == CHECKSUM_NONE, which should be the same.

Further, the virtio spec 1.0 / CS04 explicitly says that
VIRTIO_NET_HDR_F_DATA_VALID must not be set by the driver.

Fixes: fd2a0437dc33 ("virtio_net: introduce virtio_net_hdr_{from,to}_skb")
Fixes: e858fae2b0b8 (" virtio_net: use common code for virtio_net_hdr and skb GSO conversion")
Signed-off-by: Rolf Neugebauer <rolf.neugebauer@...ker.com>
Acked-by: Michael S. Tsirkin <mst@...hat.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 include/linux/virtio_net.h |    2 --
 1 file changed, 2 deletions(-)

--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -91,8 +91,6 @@ static inline int virtio_net_hdr_from_sk
 				skb_checksum_start_offset(skb));
 		hdr->csum_offset = __cpu_to_virtio16(little_endian,
 				skb->csum_offset);
-	} else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
-		hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
 	} /* else everything is zero */
 
 	return 0;