tree 5b9776e46e62588b659a61e9bbdd20614705a0fb
parent 524c6f691b99065577b245b250efe93fb0cda5c4
author Eric Dumazet <edumazet@google.com> 1464733361 -0700
committer David S. Miller <davem@davemloft.net> 1464828096 -0700

udp: avoid csum_partial() for validated skb

In commit e6afc8ace6dd5 ("udp: remove headers from UDP packets before
queueing"), udp_csum_pull_header() helper was added but missed fact
that CHECKSUM_UNNECESSARY packets were now converted to CHECKSUM_NONE
and skb->csum_valid was set to 1 for them.

Since csum_partial() is quite expensive, even for 8-byte area, it is
worth adding a test.

We also can use skb->data instead of udp_hdr() as we are pulling
UDP headers, as it is sightly faster.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>