tree 4cc5ca8299a5a4bc1b7ec09baaea25864159cdb7
parent 2853af6a2ea1a8ed09b09dd4fb578e7f435e8d34
author Eric Dumazet <edumazet@google.com> 1402614786 -0700
committer David S. Miller <davem@davemloft.net> 1402699164 -0700

udp: ipv4: do not waste time in __udp4_lib_mcast_demux_lookup

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@google.com>
Reported-by: David Held <drheld@google.com>
Cc: Shawn Bohrer <sbohrer@rgmadvisors.com>
Signed-off-by: David S. Miller <davem@davemloft.net>