1*4882a593Smuzhiyun.. SPDX-License-Identifier: GPL-2.0 2*4882a593Smuzhiyun 3*4882a593Smuzhiyun================================ 4*4882a593SmuzhiyunTC Actions - Environmental Rules 5*4882a593Smuzhiyun================================ 6*4882a593Smuzhiyun 7*4882a593Smuzhiyun 8*4882a593SmuzhiyunThe "environmental" rules for authors of any new tc actions are: 9*4882a593Smuzhiyun 10*4882a593Smuzhiyun1) If you stealeth or borroweth any packet thou shalt be branching 11*4882a593Smuzhiyun from the righteous path and thou shalt cloneth. 12*4882a593Smuzhiyun 13*4882a593Smuzhiyun For example if your action queues a packet to be processed later, 14*4882a593Smuzhiyun or intentionally branches by redirecting a packet, then you need to 15*4882a593Smuzhiyun clone the packet. 16*4882a593Smuzhiyun 17*4882a593Smuzhiyun2) If you munge any packet thou shalt call pskb_expand_head in the case 18*4882a593Smuzhiyun someone else is referencing the skb. After that you "own" the skb. 19*4882a593Smuzhiyun 20*4882a593Smuzhiyun3) Dropping packets you don't own is a no-no. You simply return 21*4882a593Smuzhiyun TC_ACT_SHOT to the caller and they will drop it. 22*4882a593Smuzhiyun 23*4882a593SmuzhiyunThe "environmental" rules for callers of actions (qdiscs etc) are: 24*4882a593Smuzhiyun 25*4882a593Smuzhiyun#) Thou art responsible for freeing anything returned as being 26*4882a593Smuzhiyun TC_ACT_SHOT/STOLEN/QUEUED. If none of TC_ACT_SHOT/STOLEN/QUEUED is 27*4882a593Smuzhiyun returned, then all is great and you don't need to do anything. 28*4882a593Smuzhiyun 29*4882a593SmuzhiyunPost on netdev if something is unclear. 30