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Diffstat (limited to 'kernel/Documentation/networking/tc-actions-env-rules.txt')
| -rw-r--r-- | kernel/Documentation/networking/tc-actions-env-rules.txt | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/kernel/Documentation/networking/tc-actions-env-rules.txt b/kernel/Documentation/networking/tc-actions-env-rules.txt new file mode 100644 index 000000000..70d6cf608 --- /dev/null +++ b/kernel/Documentation/networking/tc-actions-env-rules.txt @@ -0,0 +1,30 @@ + +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. + +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 "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. + |