30 lines
1.2 KiB
Text
30 lines
1.2 KiB
Text
|
|
||
|
|
The "enviromental" rules for authors of any new tc actions are:
|
||
|
|
|
||
|
|
1) If you stealeth or borroweth any packet thou shalt be branching
|
||
|
|
from the righteous path and thou shalt cloneth.
|
||
|
|
|
||
|
|
For example if your action queues a packet to be processed later
|
||
|
|
or intentionaly branches by redirecting a packet then you need to
|
||
|
|
clone the packet.
|
||
|
|
There are certain fields in the skb tc_verd that need to be reset so we
|
||
|
|
avoid loops etc. A few are generic enough so much so that skb_act_clone()
|
||
|
|
resets them for you. So invoke skb_act_clone() rather than skb_clone()
|
||
|
|
|
||
|
|
2) If you munge any packet thou shalt call pskb_expand_head in the case
|
||
|
|
someone else is referencing the skb. After that you "own" the skb.
|
||
|
|
You must also tell us if it is ok to munge the packet (TC_OK2MUNGE),
|
||
|
|
this way any action downstream can stomp on the packet.
|
||
|
|
|
||
|
|
3) dropping packets you dont own is a nono. You simply return
|
||
|
|
TC_ACT_SHOT to the caller and they will drop it.
|
||
|
|
|
||
|
|
The "enviromental" rules for callers of actions (qdiscs etc) are:
|
||
|
|
|
||
|
|
*) thou art responsible for freeing anything returned as being
|
||
|
|
TC_ACT_SHOT/STOLEN/QUEUED. If none of TC_ACT_SHOT/STOLEN/QUEUED is
|
||
|
|
returned then all is great and you dont need to do anything.
|
||
|
|
|
||
|
|
Post on netdev if something is unclear.
|
||
|
|
|