Commit | Line | Data |
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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 | ||
7 | For example if your action queues a packet to be processed later | |
8 | or intentionaly branches by redirecting a packet then you need to | |
9 | clone the packet. | |
10 | There are certain fields in the skb tc_verd that need to be reset so we | |
11 | avoid loops etc. A few are generic enough so much so that skb_act_clone() | |
12 | resets them for you. So invoke skb_act_clone() rather than skb_clone() | |
13 | ||
14 | 2) If you munge any packet thou shalt call pskb_expand_head in the case | |
15 | someone else is referencing the skb. After that you "own" the skb. | |
16 | You must also tell us if it is ok to munge the packet (TC_OK2MUNGE), | |
17 | this way any action downstream can stomp on the packet. | |
18 | ||
19 | 3) dropping packets you dont own is a nono. You simply return | |
20 | TC_ACT_SHOT to the caller and they will drop it. | |
21 | ||
22 | The "enviromental" rules for callers of actions (qdiscs etc) are: | |
23 | ||
24 | *) thou art responsible for freeing anything returned as being | |
25 | TC_ACT_SHOT/STOLEN/QUEUED. If none of TC_ACT_SHOT/STOLEN/QUEUED is | |
26 | returned then all is great and you dont need to do anything. | |
27 | ||
28 | Post on netdev if something is unclear. | |
29 |