diff options
Diffstat (limited to 'Documentation/networking/tc-actions-env-rules.txt')
-rw-r--r-- | Documentation/networking/tc-actions-env-rules.txt | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/Documentation/networking/tc-actions-env-rules.txt b/Documentation/networking/tc-actions-env-rules.txt index 01e716d185f4..dcadf6f88e34 100644 --- a/Documentation/networking/tc-actions-env-rules.txt +++ b/Documentation/networking/tc-actions-env-rules.txt | |||
@@ -4,26 +4,27 @@ The "enviromental" rules for authors of any new tc actions are: | |||
4 | 1) If you stealeth or borroweth any packet thou shalt be branching | 4 | 1) If you stealeth or borroweth any packet thou shalt be branching |
5 | from the righteous path and thou shalt cloneth. | 5 | from the righteous path and thou shalt cloneth. |
6 | 6 | ||
7 | For example if your action queues a packet to be processed later | 7 | For example if your action queues a packet to be processed later, |
8 | or intentionaly branches by redirecting a packet then you need to | 8 | or intentionally branches by redirecting a packet, then you need to |
9 | clone the packet. | 9 | clone the packet. |
10 | |||
10 | There are certain fields in the skb tc_verd that need to be reset so we | 11 | There are certain fields in the skb tc_verd that need to be reset so we |
11 | avoid loops etc. A few are generic enough so much so that skb_act_clone() | 12 | avoid loops, etc. A few are generic enough that skb_act_clone() |
12 | resets them for you. So invoke skb_act_clone() rather than skb_clone() | 13 | resets them for you, so invoke skb_act_clone() rather than skb_clone(). |
13 | 14 | ||
14 | 2) If you munge any packet thou shalt call pskb_expand_head in the case | 15 | 2) If you munge any packet thou shalt call pskb_expand_head in the case |
15 | someone else is referencing the skb. After that you "own" the skb. | 16 | someone else is referencing the skb. After that you "own" the skb. |
16 | You must also tell us if it is ok to munge the packet (TC_OK2MUNGE), | 17 | You must also tell us if it is ok to munge the packet (TC_OK2MUNGE), |
17 | this way any action downstream can stomp on the packet. | 18 | this way any action downstream can stomp on the packet. |
18 | 19 | ||
19 | 3) dropping packets you dont own is a nono. You simply return | 20 | 3) Dropping packets you don't own is a no-no. You simply return |
20 | TC_ACT_SHOT to the caller and they will drop it. | 21 | TC_ACT_SHOT to the caller and they will drop it. |
21 | 22 | ||
22 | The "enviromental" rules for callers of actions (qdiscs etc) are: | 23 | The "enviromental" rules for callers of actions (qdiscs etc) are: |
23 | 24 | ||
24 | *) thou art responsible for freeing anything returned as being | 25 | *) Thou art responsible for freeing anything returned as being |
25 | TC_ACT_SHOT/STOLEN/QUEUED. If none of TC_ACT_SHOT/STOLEN/QUEUED is | 26 | TC_ACT_SHOT/STOLEN/QUEUED. If none of TC_ACT_SHOT/STOLEN/QUEUED is |
26 | returned then all is great and you dont need to do anything. | 27 | returned, then all is great and you don't need to do anything. |
27 | 28 | ||
28 | Post on netdev if something is unclear. | 29 | Post on netdev if something is unclear. |
29 | 30 | ||