1
2The "environmental" rules for authors of any new tc actions are:
3
41) If you stealeth or borroweth any packet thou shalt be branching
5from the righteous path and thou shalt cloneth.
6
7For example if your action queues a packet to be processed later,
8or intentionally branches by redirecting a packet, then you need to
9clone the packet.
10
11There are certain fields in the skb tc_verd that need to be reset so we
12avoid loops, etc.  A few are generic enough that skb_act_clone()
13resets them for you, so invoke skb_act_clone() rather than skb_clone().
14
152) If you munge any packet thou shalt call pskb_expand_head in the case
16someone else is referencing the skb. After that you "own" the skb.
17You must also tell us if it is ok to munge the packet (TC_OK2MUNGE),
18this way any action downstream can stomp on the packet.
19
203) Dropping packets you don't own is a no-no. You simply return
21TC_ACT_SHOT to the caller and they will drop it.
22
23The "environmental" rules for callers of actions (qdiscs etc) are:
24
25*) Thou art responsible for freeing anything returned as being
26TC_ACT_SHOT/STOLEN/QUEUED. If none of TC_ACT_SHOT/STOLEN/QUEUED is
27returned, then all is great and you don't need to do anything.
28
29Post on netdev if something is unclear.
30
31