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ip_gre: comments change 

HARD_TX_LOCK no longer protects tunnels from dead loops,
but xmit_recursion percpu counter.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-09-29 23:35:10 -07:00 committed by David S. Miller
parent 9812cb12c9
commit 6d0722a2ce
1 changed files with 4 additions and 4 deletions
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8
net/ipv4/ip_gre.c
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@ -64,13 +64,13 @@
We cannot track such dead loops during route installation, We cannot track such dead loops during route installation,
it is infeasible task. The most general solutions would be it is infeasible task. The most general solutions would be
to keep skb->encapsulation counter (sort of local ttl), 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 solution, but it supposes maintaing new variable in ALL
skb, even if no tunneling is used. 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 2. Networking dead loops would not kill routers, but would really
kill network. IP hop limit plays role of "t->recursion" in this case, kill network. IP hop limit plays role of "t->recursion" in this case,