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d892afe2 JHS |
1 | |
2 | The "enviromental" rules for authors of any new tc actions are: | |
3 | ||
4 | 1) If you stealeth or borroweth any packet thou shalt be branching | |
5 | from the righteous path and thou shalt cloneth. | |
6 | ||
d9195881 ML |
7 | For example if your action queues a packet to be processed later, |
8 | or intentionally branches by redirecting a packet, then you need to | |
d892afe2 | 9 | clone the packet. |
d9195881 | 10 | |
d892afe2 | 11 | There are certain fields in the skb tc_verd that need to be reset so we |
d9195881 ML |
12 | avoid loops, etc. A few are generic enough that skb_act_clone() |
13 | resets them for you, so invoke skb_act_clone() rather than skb_clone(). | |
d892afe2 JHS |
14 | |
15 | 2) If you munge any packet thou shalt call pskb_expand_head in the case | |
16 | someone else is referencing the skb. After that you "own" the skb. | |
17 | You must also tell us if it is ok to munge the packet (TC_OK2MUNGE), | |
18 | this way any action downstream can stomp on the packet. | |
19 | ||
d9195881 | 20 | 3) Dropping packets you don't own is a no-no. You simply return |
d892afe2 JHS |
21 | TC_ACT_SHOT to the caller and they will drop it. |
22 | ||
23 | The "enviromental" rules for callers of actions (qdiscs etc) are: | |
24 | ||
d9195881 | 25 | *) Thou art responsible for freeing anything returned as being |
d892afe2 | 26 | TC_ACT_SHOT/STOLEN/QUEUED. If none of TC_ACT_SHOT/STOLEN/QUEUED is |
d9195881 | 27 | returned, then all is great and you don't need to do anything. |
d892afe2 JHS |
28 | |
29 | Post on netdev if something is unclear. | |
30 |