netdev - [PATCH net-next] ip_gre: comments change

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Message-ID: <1285824777.5211.663.camel@edumazet-laptop>
Date:	Thu, 30 Sep 2010 07:32:57 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next] 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@...il.com>
---
 net/ipv4/ip_gre.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 035db63..fbe2c47 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,


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