[NETFILTER]: Avoid warning on CONNTRACK_STAT_INC in death_by_timeout()

Module removal can call death_by_timeout() manually, which isn't in softirq
context, so the CONNTRACK_STAT_INC() call there (which assumes preempt
disabled) can give a warning.  Of course, the warning here is spurious, but
the simplest workaround is to call CONNTRACK_STAT_INC() inside the lock.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/netfilter/ip_conntrack_core.c

@@ -327,9 +327,10 @@ static void death_by_timeout(unsigned long ul_conntrack)
 {
 	struct ip_conntrack *ct = (void *)ul_conntrack;
 
-	CONNTRACK_STAT_INC(delete_list);
-
 	WRITE_LOCK(&ip_conntrack_lock);
+	/* Inside lock so preempt is disabled on module removal path.
+	 * Otherwise we can get spurious warnings. */
+	CONNTRACK_STAT_INC(delete_list);
 	clean_from_lists(ct);
 	WRITE_UNLOCK(&ip_conntrack_lock);
 	ip_conntrack_put(ct);