n_hdlc: invert conditions in n_hdlc_tty_close and n_hdlc_tty_poll

This makes the functions return immediatelly on invalid state. And we
can push the indent of the later code one level left.

Pass "-w" to "git show" to see we are changing only the conditions (and
whitespace).
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20200219084118.26491-8-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/n_hdlc.c

@@ -258,9 +258,11 @@ static void n_hdlc_tty_close(struct tty_struct *tty)
 {
 	struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
 
-	if (n_hdlc != NULL) {
+	if (!n_hdlc)
+		return;
+
 	if (n_hdlc->magic != HDLC_MAGIC) {
-			printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n");
+		printk(KERN_WARNING "n_hdlc: trying to close unopened tty!\n");
 		return;
 	}
 #if defined(TTY_NO_WRITE_SPLIT)
@@ -276,7 +278,6 @@ static void n_hdlc_tty_close(struct tty_struct *tty)
 	} else {
 		n_hdlc_release (n_hdlc);
 	}
-	}
 }	/* end of n_hdlc_tty_close() */
 
 /**
@@ -737,10 +738,13 @@ static __poll_t n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
 	struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
 	__poll_t mask = 0;
 
-	if (n_hdlc && n_hdlc->magic == HDLC_MAGIC && tty == n_hdlc->tty) {
-		/* queue current process into any wait queue that */
-		/* may awaken in the future (read and write) */
+	if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || tty != n_hdlc->tty)
+		return 0;
 
+	/*
+	 * queue the current process into any wait queue that may awaken in the
+	 * future (read and write)
+	 */
 	poll_wait(filp, &tty->read_wait, wait);
 	poll_wait(filp, &tty->write_wait, wait);
 
@@ -754,7 +758,7 @@ static __poll_t n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
 	if (!tty_is_writelocked(tty) &&
 			!list_empty(&n_hdlc->tx_free_buf_list.list))
 		mask |= EPOLLOUT | EPOLLWRNORM;	/* writable */
-	}
+
 	return mask;
 }	/* end of n_hdlc_tty_poll() */