Merge branch 'TC-refactor-act_mirred-packets-re-injection'

Paolo Abeni says:

====================
TC: refactor act_mirred packets re-injection

This series is aimed at improving the act_mirred redirect performances.
Such action is used by OVS to represent TC S/W flows, and it's current largest
bottle-neck is the need for a skb_clone() for each packet.

The first 2 patches introduce some cleanup and safeguards to allow extending
tca_result - we will use it to store RCU protected redirect information - and
introduce a clear separation between user-space accessible tcfa_action
values and internal values accessible only by the kernel.
Then a new tcfa_action value is introduced: TC_ACT_REINJECT, similar to
TC_ACT_REDIRECT, but preserving the mirred semantic. Such value is not
accessible from user-space.
The last patch exploits the newly introduced infrastructure in the act_mirred
action, to avoid a skb_clone, when possible.

Overall this the above gives a ~10% performance improvement in forwarding tput,
when using the TC S/W datapath.

v1 -> v2:
 - preserve the rcu lock in act_bpf
 - add and use a new action value to reinject the packets, preserving the mirred
   semantic

v2 -> v3:
 - renamed to new action as TC_ACT_REINJECT
 - TC_ACT_REINJECT is not exposed to user-space

v3 -> v4:
 - dropped the TC_ACT_REDIRECT patch
 - report failure via extack, too
 - rename the new action as TC_ACT_REINSERT
 - skip clone only if the control action don't touch tcf_result

v4 -> v5:
 - fix a couple of build issue reported by kbuild bot
 - dont split messages
====================

Signed-off-by: David S. Miller <davem@davemloft.net>