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Commit e918085a authored by Alex Williamson's avatar Alex Williamson Committed by David S. Miller
Browse files

virtio_net: Fix MAX_PACKET_LEN to support 802.1Q VLANs 



802.1Q expanded the maximum ethernet frame size by 4 bytes for the
VLAN tag.  We're not taking this into account in virtio_net, which
means the buffers we provide to the backend in the virtqueue RX ring
aren't big enough to hold a full MTU VLAN packet.  For QEMU/KVM,
this results in the backend exiting with a packet truncation error.

Signed-off-by: default avatarAlex Williamson <alex.williamson@hp.com>
Acked-by: default avatarMark McLoughlin <markmc@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 801599b0

drivers/net/virtio_net.c

+2 −1
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
#include <linux/virtio.h>

#include <linux/virtio_net.h>

#include <linux/scatterlist.h>

#include <linux/if_vlan.h>



static int napi_weight = 128;

module_param(napi_weight, int, 0444);
@@ -33,7 +34,7 @@ module_param(csum, bool, 0444); 
module_param(gso, bool, 0444);



/* FIXME: MTU in config. */

#define MAX_PACKET_LEN (ETH_HLEN+ETH_DATA_LEN)

#define MAX_PACKET_LEN (ETH_HLEN + VLAN_HLEN + ETH_DATA_LEN)

#define GOOD_COPY_LEN	128



struct virtnet_info