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>
31 lines
1.2 KiB
Plaintext
31 lines
1.2 KiB
Plaintext
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The "enviromental" rules for authors of any new tc actions are:
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1) If you stealeth or borroweth any packet thou shalt be branching
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from the righteous path and thou shalt cloneth.
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For example if your action queues a packet to be processed later,
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or intentionally branches by redirecting a packet, then you need to
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clone the packet.
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There are certain fields in the skb tc_verd that need to be reset so we
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avoid loops, etc. A few are generic enough that skb_act_clone()
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resets them for you, so invoke skb_act_clone() rather than skb_clone().
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2) If you munge any packet thou shalt call pskb_expand_head in the case
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someone else is referencing the skb. After that you "own" the skb.
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You must also tell us if it is ok to munge the packet (TC_OK2MUNGE),
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this way any action downstream can stomp on the packet.
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3) Dropping packets you don't own is a no-no. You simply return
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TC_ACT_SHOT to the caller and they will drop it.
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The "enviromental" rules for callers of actions (qdiscs etc) are:
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*) Thou art responsible for freeing anything returned as being
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TC_ACT_SHOT/STOLEN/QUEUED. If none of TC_ACT_SHOT/STOLEN/QUEUED is
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returned, then all is great and you don't need to do anything.
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Post on netdev if something is unclear.
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