Documentation/networking/tc-actions-env-rules.txt

   1
   2 The "environmental" 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 intentionally branches by redirecting a packet, then you need to
   9 clone the packet.
  10
  11 2) If you munge any packet thou shalt call pskb_expand_head in the case
  12 someone else is referencing the skb. After that you "own" the skb.
  13
  14 3) Dropping packets you don't own is a no-no. You simply return
  15 TC_ACT_SHOT to the caller and they will drop it.
  16
  17 The "environmental" rules for callers of actions (qdiscs etc) are:
  18
  19 *) Thou art responsible for freeing anything returned as being
  20 TC_ACT_SHOT/STOLEN/QUEUED. If none of TC_ACT_SHOT/STOLEN/QUEUED is
  21 returned, then all is great and you don't need to do anything.
  22
  23 Post on netdev if something is unclear.
  24