Selected device feature bits can be propagated to VLAN devices, so we
can make use of TX checksum offload and TSO on VLAN-tagged packets.
However, if the physical device does not do VLAN tag insertion or
generic checksum offload then the test for TX checksum offload in
dev_queue_xmit() will see a protocol of htons(ETH_P_8021Q) and yield
false.
This splits the checksum offload test into two functions:
- can_checksum_protocol() tests a given protocol against a feature bitmask
- dev_can_checksum() first tests the skb protocol against the device
features; if that fails and the protocol is htons(ETH_P_8021Q) then
it tests the encapsulated protocol against the effective device
features for VLANs
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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