igmp: Use next_net_device_rcu()

We need to use next_det_device_rcu() in RCU protected section.

We also can avoid in_dev_get()/in_dev_put() overhead (code size mainly)
in rcu_read_lock() sections.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/igmp.c

@@ -2313,7 +2313,8 @@ static inline struct ip_mc_list *igmp_mc_get_first(struct seq_file *seq)
 	state->in_dev = NULL;
 	for_each_netdev_rcu(net, state->dev) {
 		struct in_device *in_dev;
-		in_dev = in_dev_get(state->dev);
+
+		in_dev = __in_dev_get_rcu(state->dev);
 		if (!in_dev)
 			continue;
 		read_lock(&in_dev->mc_list_lock);
@@ -2323,7 +2324,6 @@ static inline struct ip_mc_list *igmp_mc_get_first(struct seq_file *seq)
 			break;
 		}
 		read_unlock(&in_dev->mc_list_lock);
-		in_dev_put(in_dev);
 	}
 	return im;
 }
@@ -2333,16 +2333,15 @@ static struct ip_mc_list *igmp_mc_get_next(struct seq_file *seq, struct ip_mc_li
 	struct igmp_mc_iter_state *state = igmp_mc_seq_private(seq);
 	im = im->next;
 	while (!im) {
-		if (likely(state->in_dev != NULL)) {
+		if (likely(state->in_dev != NULL))
 			read_unlock(&state->in_dev->mc_list_lock);
-			in_dev_put(state->in_dev);
-		}
-		state->dev = next_net_device(state->dev);
+
+		state->dev = next_net_device_rcu(state->dev);
 		if (!state->dev) {
 			state->in_dev = NULL;
 			break;
 		}
-		state->in_dev = in_dev_get(state->dev);
+		state->in_dev = __in_dev_get_rcu(state->dev);
 		if (!state->in_dev)
 			continue;
 		read_lock(&state->in_dev->mc_list_lock);
@@ -2384,7 +2383,6 @@ static void igmp_mc_seq_stop(struct seq_file *seq, void *v)
 	struct igmp_mc_iter_state *state = igmp_mc_seq_private(seq);
 	if (likely(state->in_dev != NULL)) {
 		read_unlock(&state->in_dev->mc_list_lock);
-		in_dev_put(state->in_dev);
 		state->in_dev = NULL;
 	}
 	state->dev = NULL;
@@ -2464,7 +2462,7 @@ static inline struct ip_sf_list *igmp_mcf_get_first(struct seq_file *seq)
 	state->im = NULL;
 	for_each_netdev_rcu(net, state->dev) {
 		struct in_device *idev;
-		idev = in_dev_get(state->dev);
+		idev = __in_dev_get_rcu(state->dev);
 		if (unlikely(idev == NULL))
 			continue;
 		read_lock(&idev->mc_list_lock);
@@ -2480,7 +2478,6 @@ static inline struct ip_sf_list *igmp_mcf_get_first(struct seq_file *seq)
 			spin_unlock_bh(&im->lock);
 		}
 		read_unlock(&idev->mc_list_lock);
-		in_dev_put(idev);
 	}
 	return psf;
 }
@@ -2494,16 +2491,15 @@ static struct ip_sf_list *igmp_mcf_get_next(struct seq_file *seq, struct ip_sf_l
 		spin_unlock_bh(&state->im->lock);
 		state->im = state->im->next;
 		while (!state->im) {
-			if (likely(state->idev != NULL)) {
+			if (likely(state->idev != NULL))
 				read_unlock(&state->idev->mc_list_lock);
-				in_dev_put(state->idev);
-			}
-			state->dev = next_net_device(state->dev);
+
+			state->dev = next_net_device_rcu(state->dev);
 			if (!state->dev) {
 				state->idev = NULL;
 				goto out;
 			}
-			state->idev = in_dev_get(state->dev);
+			state->idev = __in_dev_get_rcu(state->dev);
 			if (!state->idev)
 				continue;
 			read_lock(&state->idev->mc_list_lock);
@@ -2555,7 +2551,6 @@ static void igmp_mcf_seq_stop(struct seq_file *seq, void *v)
 	}
 	if (likely(state->idev != NULL)) {
 		read_unlock(&state->idev->mc_list_lock);
-		in_dev_put(state->idev);
 		state->idev = NULL;
 	}
 	state->dev = NULL;