datapath: simplify ovs_flow_tbl_lookup_stats()

Simplify flow mask cache replacement without using expensive atomic
memory access to the mask pointers.

Signed-off-by: Andy Zhou <azhou@nicira.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
datapath: keep mask array compact when deleting mask

When deleting a mask from the mask array, we always move the last entry
into its current location. Another approach can be NULL in its
current place, and periodically compact it.

The approach taken by this patch is more efficient during run
time.  During look up, fast path packet don't have to skip over NULL
pointers.

A more important advantage of this approach is that it tries to
keep the mask array index stable by avoiding periodic index
reshuffle.

This patch implements an optimization to further promote index
stability.  By leaving the last entry value intact when moving it
to a new location, the old cache index can 'fix' themselves, by noticing
the index in the cache is outside the valid mask array region. The
new index can be found by scanning the mask pointer within the valid
rtegion.

Signed-off-by: Andy Zhou <azhou@nicira.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
userspace: add support for pop_eth and push_eth actions

These actions will allow L2->L3 and L3->L2 switching, and are supposed
to be added to flows installed in the datapath transparently by
ovs-vswitchd.

Signed-off-by: Lorand Jakab <lojakab@cisco.com>
userspace: add layer 3 flow and switching support

This commit relaxes the assumption that all packets have an Ethernet
header, and adds support for layer 3 flows.  For each packet received on
the Linux kernel datapath the l2 and l3 members of struct ofpbuf are
intialized appropriately, and some functions now expect this (notably
flow_extract()), in order to differentiate between layer 2 and layer 3
packets.  struct flow has now a new 'base_layer' member, because we
cannot assume that a flow has no Ethernet header when eth_src and
eth_dst are 0.  For layer 3 packets, the protocol type is still stored
in the eth_type member.

Switching L2->L3 and L3->L2 are both implemented by adding the pop_eth
and push_eth actions respectively when a transition is detected.  The
push_eth action puts 0s on both source and destination MACs.  These
addresses can be modified with mod_dl_dst and mod_dl_src actions.

Added new prerequisite MFP_ETHERNET for fields MFF_ETH_SRC, MFF_ETH_DST,
MFF_VLAN_TCI, MFF_DL_VLAN, MFF_VLAN_VID and MFF_DL_VLAN_PCP.

Signed-off-by: Lorand Jakab <lojakab@cisco.com>
datapath: add layer 3 flow/port support

Implementation of the pop_eth and push_eth actions in the kernel, and
layer 3 flow support.

Signed-off-by: Lorand Jakab <lojakab@cisco.com>