[PATCH -next v2 0/5] netfilter: nf_queue: avoid expensive gso/checksums

[Florian Westphal <fw@strlen.de>]

Hello Pablo,

here is V2 of the gso avoidance patchset for nfnetlink_queue.

With these patches, userspace can now instruct the kernel that it is gso/gro
aware and can handle "invalid" checksums that appear in packet headers.

For old userspace, nothing is changed: the kernel segments gso skbs
and adjusts checksums.

To avoid gso/checksum fixup overhead, userspace applications must set the
new NFQA_CFG_F_GSO config flag via NFQA_CFG_FLAGS attribute.

Then, for every packet received, userspace needs to check for the presence
of the new NFQA_SKB_INFO attribute.  If it exists, userspace needs to test
NFQA_SKB_CSUMNOTREADY bit.  If set, this means that userspace
must NOT very packet checksums, since they will be fixed later on
by the kernel.

The other bit is
NFQA_SKB_GSO, which could be used for statistics, or to determine when
packet size exceeds mtu.

Feedback welcome.

Update for libnetfilter_queue (including example program/documentation)
will follow later.

The following changes since commit d37d696804a83479f240b397670a07ccb53a7417:

  netfilter: xt_rpfilter: depend on raw or mangle table (2013-04-19 00:22:55 +0200)

are available in the git repository at:
  git://git.breakpoint.cc/fw/nf-next.git nfqueue_gso_avoidance_06

Florian Westphal (5):
      netfilter: nf_queue: move device refcount bump to extra function
      netfilter: nfnetlink_queue: avoid peer_portid test
      netfilter: move skb_gso_segment into nfnetlink_queue module
      netfilter: nfnetlink_queue: add skb info attribute
      netfilter: nfqueue: avoid expensive gso segmentation and checksum fixup

Changes since V1:
 - fix OOPS if CONFIG_BRIDGE_NETFILTER=y and old non-gso userspace listener is killed
 - only add NFQA_SKB_INFO when skb is gso or CHECKSUM_PARTIAL

 include/net/netfilter/nf_queue.h               |    6 +
 include/uapi/linux/netfilter/nfnetlink_queue.h |   10 ++-
 net/netfilter/nf_queue.c                       |  143 +++++--------------
 net/netfilter/nfnetlink_queue_core.c           |  180 +++++++++++++++++++++---
 4 files changed, 209 insertions(+), 130 deletions(-)