|  |  | 
|  | The "environmental" 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 intentionally branches by redirecting a packet, then you need to | 
|  | clone the packet. | 
|  |  | 
|  | 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. | 
|  |  | 
|  | 3) Dropping packets you don't own is a no-no. You simply return | 
|  | TC_ACT_SHOT to the caller and they will drop it. | 
|  |  | 
|  | The "environmental" 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 don't need to do anything. | 
|  |  | 
|  | Post on netdev if something is unclear. | 
|  |  |