aboutsummaryrefslogtreecommitdiff
path: root/Documentation/networking/tc-actions-env-rules.txt
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-26 08:43:05 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-26 08:43:05 -0700
commitec3b67c11df42362ccda81261d62829042f223f0 (patch)
treeab66bc43d98e38eda7162f76208993b2280f88f3 /Documentation/networking/tc-actions-env-rules.txt
parente868171a94b637158a3930c9adfb448d0df163cd (diff)
parent4be2700fb7b95f2a7cef9324879cafccab8774fc (diff)
Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (32 commits) [NetLabel]: correct usage of RCU locking [TCP]: fix D-SACK cwnd handling [NET] napi: use non-interruptible sleep in napi_disable [SCTP] net/sctp/auth.c: make 3 functions static [TCP]: Add missing I/O AT code to ipv6 side. [SCTP]: #if 0 sctp_update_copy_cksum() [INET]: Unexport icmpmsg_statistics [NET]: Unexport sock_enable_timestamp(). [TCP]: Make tcp_match_skb_to_sack() static. [IRDA]: Make ircomm_tty static. [NET] fs/proc/proc_net.c: make a struct static [NET] dev_change_name: ignore changes to same name [NET]: Document some simple rules for actions [NET_CLS_ACT]: Use skb_act_clone [NET_CLS_ACT]: Introduce skb_act_clone [TCP]: Fix scatterlist handling in MD5 signature support. [IPSEC]: Fix scatterlist handling in skb_icv_walk(). [IPSEC]: Add missing sg_init_table() calls to ESP. [CRYPTO]: Initialize TCRYPT on-stack scatterlist objects correctly. [CRYPTO]: HMAC needs some more scatterlist fixups. ...
Diffstat (limited to 'Documentation/networking/tc-actions-env-rules.txt')
-rw-r--r--Documentation/networking/tc-actions-env-rules.txt29
1 files changed, 29 insertions, 0 deletions
diff --git a/Documentation/networking/tc-actions-env-rules.txt b/Documentation/networking/tc-actions-env-rules.txt
new file mode 100644
index 00000000000..01e716d185f
--- /dev/null
+++ b/Documentation/networking/tc-actions-env-rules.txt
@@ -0,0 +1,29 @@
+
+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 intentionaly 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 so much so 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 dont own is a nono. 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 dont need to do anything.
+
+Post on netdev if something is unclear.
+