Commit 6d0722a2 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ip_gre: comments change

HARD_TX_LOCK no longer protects tunnels from dead loops,
but xmit_recursion percpu counter.
Signed-off-by: default avatarEric Dumazet <>
Signed-off-by: default avatarDavid S. Miller <>
parent 9812cb12
......@@ -64,13 +64,13 @@
We cannot track such dead loops during route installation,
it is infeasible task. The most general solutions would be
to keep skb->encapsulation counter (sort of local ttl),
and silently drop packet when it expires. It is the best
and silently drop packet when it expires. It is a good
solution, but it supposes maintaing new variable in ALL
skb, even if no tunneling is used.
Current solution: HARD_TX_LOCK lock breaks dead loops.
Current solution: xmit_recursion breaks dead loops. This is a percpu
counter, since when we enter the first ndo_xmit(), cpu migration is
forbidden. We force an exit if this counter reaches RECURSION_LIMIT
2. Networking dead loops would not kill routers, but would really
kill network. IP hop limit plays role of "t->recursion" in this case,
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