mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-11-01 17:08:10 +00:00
d91958815d
Cc: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
30 lines
1.2 KiB
Text
30 lines
1.2 KiB
Text
|
|
The "enviromental" 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.
|
|
|
|
There are certain fields in the skb tc_verd that need to be reset so we
|
|
avoid loops, etc. A few are generic enough that skb_act_clone()
|
|
resets them for you, so invoke skb_act_clone() rather than skb_clone().
|
|
|
|
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.
|
|
You must also tell us if it is ok to munge the packet (TC_OK2MUNGE),
|
|
this way any action downstream can stomp on the packet.
|
|
|
|
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 "enviromental" 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.
|
|
|