From: Eric Dumazet Date: Thu, 30 Sep 2010 06:35:10 +0000 (-0700) Subject: ip_gre: comments change X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=6d0722a2cec2c23db3b0855ff8bb433175a16b44;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git ip_gre: comments change HARD_TX_LOCK no longer protects tunnels from dead loops, but xmit_recursion percpu counter. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index 035db6350037..fbe2c473a06a 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -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,