netdev - [PATCH net-next 0/3] net: Eliminate gso_send

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Date:	Sat, 20 Sep 2014 14:52:27 -0700
From:	Tom Herbert <therbert@...gle.com>
To:	davem@...emloft.net, netdev@...r.kernel.org
Subject: [PATCH net-next 0/3] net: Eliminate gso_send_check

gso_send_check presents a lot of complexity for what it is being used
for. It seems that there are only two cases where it might be effective:
TCP and UFO paths. In these cases, the gso_send_check function
initializes the TCP or UDP checksum respectively to the pseudo header
checksum so that the checksum computation is appropriately offloaded or
computed in the gso_segment functions. The gso_send_check functions
are only called from dev.c in skb_mac_gso_segment when ip_summed !=
CHECKSUM_PARTIAL (which seems very unlikely in TCP case). We can move
the logic of this into the respective gso_segment functions where the
checksum is initialized if ip_summed != CHECKSUM_PARTIAL.

With the above cases handled, gso_send_check is no longer needed, so
we can remove all uses of it and the fields in the offload callbacks.
With this change, ip_summed in the skb should be preserved though all
the layers of gso_segment calls.

In follow-on patches, we may be able to remove the check setup code in
tcp_gso_segment if we can guarantee that ip_summed will always be
CHECKSUM_PARTIAL (verify all paths and probably add an assert in
tcp_gro_segment).

Tested these patches by:
  - netperf TCP_STREAM test with GSO enabled
  - Forced ip_summed != CHECKSUM_PARTIAL with above
  - Ran UDP_RR with 10000 request size over GRE tunnel. This exercised
    UFO path.

Tom Herbert (3):
  tcp: move logic out of tcp_v[64]_gso_send_check
  udp: move logic out of udp[46]_ufo_send_check
  net: Remove gso_send_check as an offload callback

 include/linux/netdevice.h |  1 -
 net/core/dev.c            | 10 ----------
 net/ipv4/af_inet.c        | 36 ------------------------------------
 net/ipv4/gre_offload.c    | 11 +++--------
 net/ipv4/tcp_offload.c    | 45 +++++++++++++++++++++++----------------------
 net/ipv4/udp_offload.c    | 43 +++++++++++++++----------------------------
 net/ipv6/ip6_offload.c    | 27 ---------------------------
 net/ipv6/tcpv6_offload.c  | 43 ++++++++++++++++++++++++-------------------
 net/ipv6/udp_offload.c    | 46 ++++++++++++++++++----------------------------
 net/mpls/mpls_gso.c       |  7 -------
 10 files changed, 83 insertions(+), 186 deletions(-)

-- 
2.1.0.rc2.206.gedb03e5

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