RFC : Flexible SFQ flow classification

One good thing about ESFQ is the more flexible flow classification, but I don't like the concept of having a set of selectable hash functions very much.

These patches change SFQ to allow attaching external classifiers and add a new "flow" classifier that allows to classify flows based on an arbitary combination of pre-defined keys. Its probably not the fastest classifier when used with multiple keys, but frankly, I don't think speed is very important in most situations where the current SFQ implementation is used.

It currently does not support perturbation, I didn't want to move this into the classifier, so I need to think about a way to handle it within SFQ.

Some examples:

# behave identical to internal SFQ hash
tc filter add ... flow baseclass x:1 classes 1024 \
		       keys src,dst,proto-src,proto-dst

# the same, but based on source address/port before NAT
tc filter add ... flow baseclass x:1 classes 1024 \
		       keys nfct-src,dst,nfct-proto-src,proto-dst

# classify based on UID
tc filter add ... flow baseclass x:1 classes 1024 \
		       keys sk-uid

and so on .. check out the iproute help text for the full set of supported keys.

Comments welcome.

 include/linux/pkt_cls.h |   37 +++
 net/sched/Kconfig       |   11 
 net/sched/Makefile      |    1 
 net/sched/cls_flow.c    |  570 ++++++++++++++++++++++++++++++++++++++++++++++++
 net/sched/sch_sfq.c     |   98 +++++++-
 5 files changed, 713 insertions(+), 4 deletions(-)

Patrick McHardy (2):
[NET_SCHED]: sch_sfq: add support for external classifiers [NET_SCHED]: Add flow classifier