Merge branch 'net-zerocopy-refine'

Willem de Bruijn says:

====================
zerocopy refinements

1/4 is a small optimization follow-up to the earlier fix to skb_segment:
    check skb state once per skb, instead of once per frag.
2/4 makes behavior more consistent between standard and zerocopy send:
    set the PSH bit when hitting MAX_SKB_FRAGS. This helps GRO.
3/4 resolves a surprising inconsistency in notification:
    because small packets were not stored in frags, they would not set
    the copied error code over loopback. This change also optimizes
    the path by removing copying and making tso_fragment cheaper.
4/4 follows-up to 3/4 by no longer allocated now unused memory.
    this was actually already in RFC patches, but dropped as I pared
    down the patch set during revisions.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>