Merge branch 'udp-msg_zerocopy'
Willem de Bruijn says:
====================
udp msg_zerocopy
Enable MSG_ZEROCOPY for udp sockets
Patch 1/3 is the main patch, a rework of RFC patch
http://patchwork.ozlabs.org/patch/899630/
more details in the patch commit message
Patch 2/3 is an optimization to remove a branch from the UDP hot path
and refcount_inc/refcount_dec_and_test pair when zerocopy is used.
This used to be included in the first patch in v2.
Patch 3/3 runs the already existing udp zerocopy tests
as part of kselftest
See also recent Linux Plumbers presentation
https://linuxplumbersconf.org/event/2/contributions/106/attachments/104/128/willemdebruijn-lpc2018-udpgso-presentation-20181113.pdf
Changes:
v1 -> v2
- Fixup reverse christmas tree violation
v2 -> v3
- Split refcount avoidance optimization into separate patch
- Fix refcount leak on error in fragmented case
(thanks to Paolo Abeni for pointing this one out!)
- Fix refcount inc on zero
v3 -> v4
- Move skb_zcopy_set below the only kfree_skb that might cause
a premature uarg destroy before skb_zerocopy_put_abort
- Move the entire skb_shinfo assignment block, to keep that
cacheline access in one place
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
