From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 9 Jun 2010 16:21:07 +0000 (+0000)
Subject: ip: ip_ra_control() rcu fix
X-Git-Tag: v2.6.36-rc1~571^2~617
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=592fcb9dfafaa02dd0edc207bf5d3a0ee7a1f8df;p=pandora-kernel.git

ip: ip_ra_control() rcu fix

commit 66018506e15b (ip: Router Alert RCU conversion) introduced RCU
lookups to ip_call_ra_chain(). It missed proper deinit phase :
When ip_ra_control() deletes an ip_ra_chain, it should make sure
ip_call_ra_chain() users can not start to use socket during the rcu
grace period. It should also delay the sock_put() after the grace
period, or we risk a premature socket freeing and corruptions, as
raw sockets are not rcu protected yet.

This delay avoids using expensive atomic_inc_not_zero() in
ip_call_ra_chain().

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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