This is a note to let you know that I've just added the patch titled
udp: ipv4: do not waste time in
to the 3.15-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:
udp-ipv4-do-not-waste-time-in.patch
and it can be found in the queue-3.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Wed Jun 18 20:31:04 PDT 2014
From: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Thu, 12 Jun 2014 16:13:06 -0700
Subject: udp: ipv4: do not waste time in
__udp4_lib_mcast_demux_lookup
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 63c6f81cdde58c41da62a8d8a209592e42a0203e ]
Its too easy to add thousand of UDP sockets on a particular bucket,
and slow down an innocent multicast receiver.
Early demux is supposed to be an optimization, we should avoid spending
too much time in it.
It is interesting to note __udp4_lib_demux_lookup() only tries to
match first socket in the chain.
10 is the threshold we already have in __udp4_lib_lookup() to switch
to secondary hash.
Fixes: 421b3885bf6d5 ("udp: ipv4: Add udp early demux")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reported-by: David Held <drheld@xxxxxxxxxx>
Cc: Shawn Bohrer <sbohrer@xxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/udp.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1834,6 +1834,10 @@ static struct sock *__udp4_lib_mcast_dem
unsigned int count, slot = udp_hashfn(net, hnum, udp_table.mask);
struct udp_hslot *hslot = &udp_table.hash[slot];
+ /* Do not bother scanning a too big list */
+ if (hslot->count > 10)
+ return NULL;
+
rcu_read_lock();
begin:
count = 0;
Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are
queue-3.15/ipv6-fix-regression-caused-by-efe4208-in.patch
queue-3.15/net-force-a-list_del-in-unregister_netdevice_many.patch
queue-3.15/udp-ipv4-do-not-waste-time-in.patch
queue-3.15/ipv4-fix-a-race-in-ip4_datagram_release_cb.patch
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