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d2461edd MCC |
1 | .. SPDX-License-Identifier: GPL-2.0 |
2 | ||
3 | ================================ | |
4 | TC Actions - Environmental Rules | |
5 | ================================ | |
6 | ||
7 | ||
8 | The "environmental" rules for authors of any new tc actions are: | |
9 | ||
10 | 1) If you stealeth or borroweth any packet thou shalt be branching | |
11 | from the righteous path and thou shalt cloneth. | |
12 | ||
13 | For example if your action queues a packet to be processed later, | |
14 | or intentionally branches by redirecting a packet, then you need to | |
15 | clone the packet. | |
16 | ||
17 | 2) If you munge any packet thou shalt call pskb_expand_head in the case | |
18 | someone else is referencing the skb. After that you "own" the skb. | |
19 | ||
20 | 3) Dropping packets you don't own is a no-no. You simply return | |
21 | TC_ACT_SHOT to the caller and they will drop it. | |
22 | ||
23 | The "environmental" rules for callers of actions (qdiscs etc) are: | |
24 | ||
25 | #) Thou art responsible for freeing anything returned as being | |
26 | TC_ACT_SHOT/STOLEN/QUEUED. If none of TC_ACT_SHOT/STOLEN/QUEUED is | |
27 | returned, then all is great and you don't need to do anything. | |
28 | ||
29 | Post on netdev if something is unclear. |