drivers/net: remove some rcu sparse warnings

Add missing __rcu annotations and helpers.
minor : Fix some rcu_dereference() calls in macvtap

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/hamradio/bpqether.c b/drivers/net/hamradio/bpqether.c
index ac1d323..8931168 100644
--- a/drivers/net/hamradio/bpqether.c
+++ b/drivers/net/hamradio/bpqether.c
@@ -400,13 +400,14 @@
 static void *bpq_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
 	struct list_head *p;
+	struct bpqdev *bpqdev = v;
 
 	++*pos;
 
 	if (v == SEQ_START_TOKEN)
-		p = rcu_dereference(bpq_devices.next);
+		p = rcu_dereference(list_next_rcu(&bpq_devices));
 	else
-		p = rcu_dereference(((struct bpqdev *)v)->bpq_list.next);
+		p = rcu_dereference(list_next_rcu(&bpqdev->bpq_list));
 
 	return (p == &bpq_devices) ? NULL 
 		: list_entry(p, struct bpqdev, bpq_list);