[IPVS]: Add and reorder bh locks after moving to keventd.

An addition to the last ipvs changes that move
update_defense_level/si_meminfo to keventd:

- ip_vs_random_dropentry now runs in process context and should use _bh
  locks to protect from softirqs

- update_defense_level still needs _bh locks after si_meminfo is called,
  for the same purpose
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ipvs/ip_vs_conn.c

@@ -758,7 +758,7 @@ static inline int todrop_entry(struct ip_vs_conn *cp)
 	return 1;
 }
 
-
+/* Called from keventd and must protect itself from softirqs */
 void ip_vs_random_dropentry(void)
 {
 	int idx;
@@ -773,7 +773,7 @@ void ip_vs_random_dropentry(void)
 		/*
 		 *  Lock is actually needed in this loop.
 		 */
-		ct_write_lock(hash);
+		ct_write_lock_bh(hash);
 
 		list_for_each_entry(cp, &ip_vs_conn_tab[hash], c_list) {
 			if (!cp->cport && !(cp->flags & IP_VS_CONN_F_NO_CPORT))
@@ -806,7 +806,7 @@ void ip_vs_random_dropentry(void)
 				ip_vs_conn_expire_now(cp->control);
 			}
 		}
-		ct_write_unlock(hash);
+		ct_write_unlock_bh(hash);
 	}
 }
 

net/ipv4/ipvs/ip_vs_ctl.c

@@ -90,7 +90,8 @@ int ip_vs_get_debug_level(void)
 #endif
 
 /*
- *	update_defense_level is called from keventd and from sysctl.
+ *	update_defense_level is called from keventd and from sysctl,
+ *	so it needs to protect itself from softirqs
  */
 static void update_defense_level(void)
 {
@@ -110,6 +111,8 @@ static void update_defense_level(void)
 
 	nomem = (availmem < sysctl_ip_vs_amemthresh);
 
+	local_bh_disable();
+
 	/* drop_entry */
 	spin_lock(&__ip_vs_dropentry_lock);
 	switch (sysctl_ip_vs_drop_entry) {
@@ -206,6 +209,8 @@ static void update_defense_level(void)
 	if (to_change >= 0)
 		ip_vs_protocol_timeout_change(sysctl_ip_vs_secure_tcp>1);
 	write_unlock(&__ip_vs_securetcp_lock);
+
+	local_bh_enable();
 }
 
 
@@ -1360,9 +1365,7 @@ proc_do_defense_mode(ctl_table *table, int write, struct file * filp,
 			/* Restore the correct value */
 			*valp = val;
 		} else {
-			local_bh_disable();
 			update_defense_level();
-			local_bh_enable();
 		}
 	}
 	return rc;