netdev - Re: [PATCH] udp: ipv4: do not waste time in __udp4_lib_mcast_demux

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Message-Id: <20140613.153947.1190933976866000224.davem@davemloft.net>
Date:	Fri, 13 Jun 2014 15:39:47 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	netdev@...r.kernel.org, sbohrer@...advisors.com, drheld@...gle.com,
	willemb@...gle.com
Subject: Re: [PATCH] udp: ipv4: do not waste time in
 __udp4_lib_mcast_demux_lookup

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Thu, 12 Jun 2014 16:13:06 -0700

> From: Eric Dumazet <edumazet@...gle.com>
> 
> 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@...gle.com>
> Reported-by: David Held <drheld@...gle.com>

Applied and queued up for -stable, thanks Eric.
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