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