drivers/net: Use RCU_INIT_POINTER(x, NULL) in tun.c

This patch replaces rcu_assign_pointer(x, NULL) with RCU_INIT_POINTER(x, NULL)

The rcu_assign_pointer() ensures that the initialization of a structure
is carried out before storing a pointer to that structure.
And in the case of the NULL pointer, there is no structure to initialize.
So, rcu_assign_pointer(p, NULL) can be safely converted to RCU_INIT_POINTER(p, NULL)
Signed-off-by: NMonam Agarwal <monamagarwal123@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/tun.c

@@ -452,7 +452,7 @@ static void __tun_detach(struct tun_file *tfile, bool clean)
 
 		--tun->numqueues;
 		if (clean) {
-			rcu_assign_pointer(tfile->tun, NULL);
+			RCU_INIT_POINTER(tfile->tun, NULL);
 			sock_put(&tfile->sk);
 		} else
 			tun_disable_queue(tun, tfile);
@@ -499,12 +499,12 @@ static void tun_detach_all(struct net_device *dev)
 		tfile = rtnl_dereference(tun->tfiles[i]);
 		BUG_ON(!tfile);
 		wake_up_all(&tfile->wq.wait);
-		rcu_assign_pointer(tfile->tun, NULL);
+		RCU_INIT_POINTER(tfile->tun, NULL);
 		--tun->numqueues;
 	}
 	list_for_each_entry(tfile, &tun->disabled, next) {
 		wake_up_all(&tfile->wq.wait);
-		rcu_assign_pointer(tfile->tun, NULL);
+		RCU_INIT_POINTER(tfile->tun, NULL);
 	}
 	BUG_ON(tun->numqueues != 0);
 
@@ -2194,7 +2194,7 @@ static int tun_chr_open(struct inode *inode, struct file * file)
 					    &tun_proto);
 	if (!tfile)
 		return -ENOMEM;
-	rcu_assign_pointer(tfile->tun, NULL);
+	RCU_INIT_POINTER(tfile->tun, NULL);
 	tfile->net = get_net(current->nsproxy->net_ns);
 	tfile->flags = 0;
 	tfile->ifindex = 0;