net: fix rcu access on phonet_routes

-Add __rcu annotation on table to fix sparse warnings:
net/phonet/pn_dev.c:279:25: warning: incorrect type in assignment (different address spaces)
net/phonet/pn_dev.c:279:25: expected struct net_device *<noident>
net/phonet/pn_dev.c:279:25: got void [noderef] <asn:4>*<noident>
net/phonet/pn_dev.c:376:17: warning: incorrect type in assignment (different address spaces)
net/phonet/pn_dev.c:376:17: expected struct net_device *volatile <noident>
net/phonet/pn_dev.c:376:17: got struct net_device [noderef] <asn:4>*<noident>
net/phonet/pn_dev.c:392:17: warning: incorrect type in assignment (different address spaces)
net/phonet/pn_dev.c:392:17: expected struct net_device *<noident>
net/phonet/pn_dev.c:392:17: got void [noderef] <asn:4>*<noident>

-Access table with rcu_access_pointer (fixes the following sparse errors):
net/phonet/pn_dev.c:278:25: error: incompatible types in comparison expression (different address spaces)
net/phonet/pn_dev.c:391:17: error: incompatible types in comparison expression (different address spaces)

Suggested-by: Eric Dumazet <[e-mail]>
Signed-off-by: Fabian Frederick <[e-mail]>
Acked-by: Eric Dumazet <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/phonet/pn_dev.c

···
 
 struct phonet_routes {
 	struct mutex		lock;
-	struct net_device	*table[64];
+	struct net_device __rcu	*table[64];
 };
 
 struct phonet_net {
···
 	bitmap_zero(deleted, 64);
 	mutex_lock(&pnn->routes.lock);
 	for (i = 0; i < 64; i++)
-		if (dev == pnn->routes.table[i]) {
+		if (rcu_access_pointer(pnn->routes.table[i]) == dev) {
 			RCU_INIT_POINTER(pnn->routes.table[i], NULL);
 			set_bit(i, deleted);
 		}
···
 
 	daddr = daddr >> 2;
 	mutex_lock(&routes->lock);
-	if (dev == routes->table[daddr])
+	if (rcu_access_pointer(routes->table[daddr]) == dev)
 		RCU_INIT_POINTER(routes->table[daddr], NULL);
 	else
 		dev = NULL;