From: Eric Dumazet <edumazet@google.com>
Date: Sun, 19 Aug 2012 10:31:48 +0000 (+0200)
Subject: xfrm: fix RCU bugs
X-Git-Tag: omap-for-v3.7-rc1/fixes-cpufreq-signed~47^2~297
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ef8531b64c3e2443da52e9f05d74a988230eedc5;p=pandora-kernel.git

xfrm: fix RCU bugs

This patch reverts commit 56892261ed1a (xfrm: Use rcu_dereference_bh to
deference pointer protected by rcu_read_lock_bh), and fixes bugs
introduced in commit 418a99ac6ad ( Replace rwlock on xfrm_policy_afinfo
with rcu )

1) We properly use RCU variant in this file, not a mix of RCU/RCU_BH

2) We must defer some writes after the synchronize_rcu() call or a reader
 can crash dereferencing NULL pointer.

3) Now we use the xfrm_policy_afinfo_lock spinlock only from process
context, we no longer need to block BH in xfrm_policy_register_afinfo()
and xfrm_policy_unregister_afinfo()

4) Can use RCU_INIT_POINTER() instead of rcu_assign_pointer() in
xfrm_policy_unregister_afinfo()

5) Remove a forward inline declaration (xfrm_policy_put_afinfo()),
  and also move xfrm_policy_get_afinfo() declaration.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Fan Du <fan.du@windriver.com>
Cc: Priyanka Jain <Priyanka.Jain@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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