ofproto-dpif: Make bonding balance test more robust

It is my observation that when sending 91 packets to a mode=balance
bond interface with three underlying ports in some cases not all ports
receive at least 7 packets. This causes the test to fail.

It may be that failure indicates that the bonding code
needs improvement. But it seems to me that its more likely to
be a valid behaviour.

I have found that by sending 256 packets instead of 91 the test passes
more reliably: I am yet to see it fail.

Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Andy Zhou <azhou@nicira.com>
ofproto: Fix potential leak during flow mods.

This code created a cls_rule without destroying it.  Found by
inspection.

Signed-off-by: Ethan Jackson <ethan@nicira.com>
Acked-by: Jarno Rajahalme <jrajahalme@nicira.com>
ofproto: Fix is_flow_deletion_pending() false positive.

If one tries to install a rule that's identical to another rule in
another OpenFlow table which is being deleted, it's possible that
is_flow_deletion_pending() might confuse them and block the
installation.  This is such an edge case I doubt it has ever actually
happened.

Found by inspection.

Signed-off-by: Ethan Jackson <ethan@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
datapath: handle recirculation loop detection

Current datapath limits the number of times same packet can loop
through action execution to avoid blowing out the kernel stack.
Recirculation also adds to action execution count, but does not use
the same amount of stack compare to other services, such as IPsec.

This patch introduces the concept of stack cost. Recirculation has a
stack cost of 1 while other services have stack cost of 4. Datapath
packet process can accommodate packets that need both services and
recirculation as long as the total stack cost does not exceed the max
stack cost. Packets exceed the limit will be treated as looped packets
and dropped.

The max stack cost is set to allow up to 4 regular services, plus up
to 3 recirculation. The behavior of packets do not recirculate does
not change.

Signed-off-by: Andy Zhou <azhou@nicira.com>
Acked-by: Jesse Gross <jesse@nicira.com>
datapath: Add support for kernel 3.14.
datapath: clear l4_rxhash in skb_clear_hash.