Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 24 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 000000000..f37814693
--- /dev/null
+++ b/Documentation/networking/tc-actions-env-rules.txt
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+
+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.
+
+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.
+
+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.
+