ipmr: convert /proc handlers to rcu_read_lock()

We can use standard rcu_read_lock(), to get rid
of last read_lock(&mrt_lock) call points.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/ipmr.c

@@ -2895,7 +2895,7 @@ static int ipmr_rtm_dumplink(struct sk_buff *skb, struct netlink_callback *cb)
  */
 
 static void *ipmr_vif_seq_start(struct seq_file *seq, loff_t *pos)
-	__acquires(mrt_lock)
+	__acquires(RCU)
 {
 	struct mr_vif_iter *iter = seq->private;
 	struct net *net = seq_file_net(seq);
@@ -2907,14 +2907,14 @@ static void *ipmr_vif_seq_start(struct seq_file *seq, loff_t *pos)
 
 	iter->mrt = mrt;
 
-	read_lock(&mrt_lock);
+	rcu_read_lock();
 	return mr_vif_seq_start(seq, pos);
 }
 
 static void ipmr_vif_seq_stop(struct seq_file *seq, void *v)
-	__releases(mrt_lock)
+	__releases(RCU)
 {
-	read_unlock(&mrt_lock);
+	rcu_read_unlock();
 }
 
 static int ipmr_vif_seq_show(struct seq_file *seq, void *v)

net/ipv6/ip6mr.c

@@ -404,7 +404,7 @@ static void ip6mr_free_table(struct mr_table *mrt)
  */
 
 static void *ip6mr_vif_seq_start(struct seq_file *seq, loff_t *pos)
-	__acquires(mrt_lock)
+	__acquires(RCU)
 {
 	struct mr_vif_iter *iter = seq->private;
 	struct net *net = seq_file_net(seq);
@@ -416,14 +416,14 @@ static void *ip6mr_vif_seq_start(struct seq_file *seq, loff_t *pos)
 
 	iter->mrt = mrt;
 
-	read_lock(&mrt_lock);
+	rcu_read_lock();
 	return mr_vif_seq_start(seq, pos);
 }
 
 static void ip6mr_vif_seq_stop(struct seq_file *seq, void *v)
-	__releases(mrt_lock)
+	__releases(RCU)
 {
-	read_unlock(&mrt_lock);
+	rcu_read_unlock();
 }
 
 static int ip6mr_vif_seq_show(struct seq_file *seq, void *v)