0001 .. SPDX-License-Identifier: GPL-2.0
0002
0003 ================================
0004 TC Actions - Environmental Rules
0005 ================================
0006
0007
0008 The "environmental" rules for authors of any new tc actions are:
0009
0010 1) If you stealeth or borroweth any packet thou shalt be branching
0011 from the righteous path and thou shalt cloneth.
0012
0013 For example if your action queues a packet to be processed later,
0014 or intentionally branches by redirecting a packet, then you need to
0015 clone the packet.
0016
0017 2) If you munge any packet thou shalt call pskb_expand_head in the case
0018 someone else is referencing the skb. After that you "own" the skb.
0019
0020 3) Dropping packets you don't own is a no-no. You simply return
0021 TC_ACT_SHOT to the caller and they will drop it.
0022
0023 The "environmental" rules for callers of actions (qdiscs etc) are:
0024
0025 #) Thou art responsible for freeing anything returned as being
0026 TC_ACT_SHOT/STOLEN/QUEUED. If none of TC_ACT_SHOT/STOLEN/QUEUED is
0027 returned, then all is great and you don't need to do anything.
0028
0029 Post on netdev if something is unclear.
