tc/actions: introduce support for jump action

tc/actions: introduce support for jump action

Sample use case:

... add ingress qdisc
sudo $TC qdisc add dev $ETH ingress

 ... if we exceed rate of 1kbps (burst of 90K), do an absolute jump of 2 actions
sudo $TC actions add action police rate 1kbit burst 90k conform-exceed jump 2 / pipe

sudo $TC -s actions ls action police
 action order 0:  police 0x4 rate 1Kbit burst 23440b mtu 2Kb action jump 2/pipe overhead 0b
 ref 1 bind 0 installed 41 sec used 41 sec
 Action statistics:
  Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
  backlog 0b 0p requeues 0

... lets add a couple of marks so we can use them to mark exceed/not exceed
sudo $TC actions add action skbedit mark 11 ok index 11
sudo $TC actions add action skbedit mark 12 ok index 12

... if we dont exceed our rate we get a mark of 11, else mark of 12
sudo $TC filter add dev $ETH parent ffff: protocol ip prio 8 u32 \
match ip dst 127.0.0.8/32 flowid 1:10 \
action police index 4 \
action skbedit index 11 \
action skbedit index 12

Ok, lets keep this thing a little busy..
sudo ping -f -c 10000 127.0.0.8

... now lets see the filters..
sudo $TC -s filter ls dev $ETH parent ffff: protocol ip
filter pref 8 u32 chain 0
filter pref 8 u32 chain 0 fh 800: ht divisor 1
filter pref 8 u32 chain 0 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:10 not_in_hw  (rule hit 20000 success 10000)
  match 7f000008/ffffffff at 16 (success 10000 )
	action order 1:  police 0x4 rate 1Kbit burst 23440b mtu 2Kb action jump 2/pipe overhead 0b
	ref 2 bind 1 installed 198 sec used 2 sec
	Action statistics:
	Sent 840000 bytes 10000 pkt (dropped 0, overlimits 9721 requeues 0)
	backlog 0b 0p requeues 0

	action order 2:  skbedit mark 11 pass
	 index 11 ref 2 bind 1 installed 127 sec used 2 sec
 	Action statistics:
	Sent 23436 bytes 279 pkt (dropped 0, overlimits 0 requeues 0)
	backlog 0b 0p requeues 0

	action order 3:  skbedit mark 12 pass
	 index 12 ref 2 bind 1 installed 127 sec used 2 sec
 	Action statistics:
	Sent 816564 bytes 9721 pkt (dropped 0, overlimits 0 requeues 0)
	backlog 0b 0p requeues 0

As can be seen 97.21% of the packets were marked as exceeding the allocated
rate; you could do something clever with the skb mark after this.

Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>