Commit e918085a authored Jan 25, 2009 by Alex Williamson Committed by David S. Miller Jan 25, 2009

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: Alex Williamson <alex.williamson@hp.com>
Acked-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: David 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

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