This is a note to let you know that I've just added the patch titled
ipv4: do not cache looped multicasts
to the 3.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipv4-do-not-cache-looped-multicasts.patch
and it can be found in the queue-3.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 38c3bfd5aca185ba44c0b418d9bbb7619d95be01 Mon Sep 17 00:00:00 2001
From: Julian Anastasov <[email protected]>
Date: Thu, 22 Nov 2012 23:04:14 +0200
Subject: ipv4: do not cache looped multicasts
From: Julian Anastasov <[email protected]>
[ Upstream commit 636174219b52b5a8bc51bc23bbcba97cd30a65e3 ]
Starting from 3.6 we cache output routes for
multicasts only when using route to 224/4. For local receivers
we can set RTCF_LOCAL flag depending on the membership but
in such case we use maddr and saddr which are not caching
keys as before. Additionally, we can not use same place to
cache routes that differ in RTCF_LOCAL flag value.
Fix it by caching only RTCF_MULTICAST entries
without RTCF_LOCAL (send-only, no loopback). As a side effect,
we avoid unneeded lookup for fnhe when not caching because
multicasts are not redirected and they do not learn PMTU.
Thanks to Maxime Bizon for showing the caching
problems in __mkroute_output for 3.6 kernels: different
RTCF_LOCAL flag in cache can lead to wrong ip_mc_output or
ip_output call and the visible problem is that traffic can
not reach local receivers via loopback.
Reported-by: Maxime Bizon <[email protected]>
Tested-by: Maxime Bizon <[email protected]>
Signed-off-by: Julian Anastasov <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
net/ipv4/route.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1785,6 +1785,7 @@ static struct rtable *__mkroute_output(c
if (dev_out->flags & IFF_LOOPBACK)
flags |= RTCF_LOCAL;
+ do_cache = true;
if (type == RTN_BROADCAST) {
flags |= RTCF_BROADCAST | RTCF_LOCAL;
fi = NULL;
@@ -1793,6 +1794,8 @@ static struct rtable *__mkroute_output(c
if (!ip_check_mc_rcu(in_dev, fl4->daddr, fl4->saddr,
fl4->flowi4_proto))
flags &= ~RTCF_LOCAL;
+ else
+ do_cache = false;
/* If multicast route do not exist use
* default one, but do not gateway in this case.
* Yes, it is hack.
@@ -1802,8 +1805,8 @@ static struct rtable *__mkroute_output(c
}
fnhe = NULL;
- do_cache = fi != NULL;
- if (fi) {
+ do_cache &= fi != NULL;
+ if (do_cache) {
struct rtable __rcu **prth;
struct fib_nh *nh = &FIB_RES_NH(*res);
Patches currently in stable-queue which might be from [email protected] are
queue-3.6/ipv4-do-not-cache-looped-multicasts.patch
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