TTY/Serial fixes for 3.18-rc4

Here are some tiny serial/tty fixes for 3.18-rc4 that resolve some
 reported issues.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-3.18-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial fixes from Greg KH:
 "Here are some tiny serial/tty fixes for 3.18-rc4 that resolve some
  reported issues"

* tag 'tty-3.18-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  tty: Fix pty master poll() after slave closes v2
  serial: of-serial: fix uninitialized kmalloc variable
  tty/vt: don't set font mappings on vc not supporting this
  tty: serial: 8250_mtk: Fix quot calculation
  tty: Prevent "read/write wait queue active!" log flooding
  tty: Fix high cpu load if tty is unreleaseable
  serial: Fix divide-by-zero fault in uart_get_divisor()

drivers/tty/n_tty.c

@@ -2413,12 +2413,17 @@ static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file,
 
 	poll_wait(file, &tty->read_wait, wait);
 	poll_wait(file, &tty->write_wait, wait);
-	if (input_available_p(tty, 1))
-		mask |= POLLIN | POLLRDNORM;
-	if (tty->packet && tty->link->ctrl_status)
-		mask |= POLLPRI | POLLIN | POLLRDNORM;
 	if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 		mask |= POLLHUP;
+	if (input_available_p(tty, 1))
+		mask |= POLLIN | POLLRDNORM;
+	else if (mask & POLLHUP) {
+		tty_flush_to_ldisc(tty);
+		if (input_available_p(tty, 1))
+			mask |= POLLIN | POLLRDNORM;
+	}
+	if (tty->packet && tty->link->ctrl_status)
+		mask |= POLLPRI | POLLIN | POLLRDNORM;
 	if (tty_hung_up_p(file))
 		mask |= POLLHUP;
 	if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) {

drivers/tty/serial/8250/8250_mtk.c

@@ -81,7 +81,7 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
 		/* Set to highest baudrate supported */
 		if (baud >= 1152000)
 			baud = 921600;
-		quot = DIV_ROUND_CLOSEST(port->uartclk, 256 * baud);
+		quot = (port->uartclk / (256 * baud)) + 1;
 	}
 
 	/*

drivers/tty/serial/of_serial.c

@@ -158,7 +158,7 @@ static int of_platform_serial_probe(struct platform_device *ofdev)
 	if (of_find_property(ofdev->dev.of_node, "used-by-rtas", NULL))
 		return -EBUSY;
 
-	info = kmalloc(sizeof(*info), GFP_KERNEL);
+	info = kzalloc(sizeof(*info), GFP_KERNEL);
 	if (info == NULL)
 		return -ENOMEM;
 

drivers/tty/serial/serial_core.c

@@ -363,7 +363,7 @@ uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
 		 * The spd_hi, spd_vhi, spd_shi, spd_warp kludge...
 		 * Die! Die! Die!
 		 */
-		if (baud == 38400)
+		if (try == 0 && baud == 38400)
 			baud = altbaud;
 
 		/*

drivers/tty/tty_io.c

@@ -1709,6 +1709,8 @@ int tty_release(struct inode *inode, struct file *filp)
 	int	pty_master, tty_closing, o_tty_closing, do_sleep;
 	int	idx;
 	char	buf[64];
+	long	timeout = 0;
+	int	once = 1;
 
 	if (tty_paranoia_check(tty, inode, __func__))
 		return 0;
@@ -1789,11 +1791,18 @@ int tty_release(struct inode *inode, struct file *filp)
 		if (!do_sleep)
 			break;
 
-		printk(KERN_WARNING "%s: %s: read/write wait queue active!\n",
-				__func__, tty_name(tty, buf));
+		if (once) {
+			once = 0;
+			printk(KERN_WARNING "%s: %s: read/write wait queue active!\n",
+			       __func__, tty_name(tty, buf));
+		}
 		tty_unlock_pair(tty, o_tty);
 		mutex_unlock(&tty_mutex);
-		schedule();
+		schedule_timeout_killable(timeout);
+		if (timeout < 120 * HZ)
+			timeout = 2 * timeout + 1;
+		else
+			timeout = MAX_SCHEDULE_TIMEOUT;
 	}
 
 	/*

drivers/tty/vt/consolemap.c

@@ -539,6 +539,12 @@ int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list)
 
 	/* Save original vc_unipagdir_loc in case we allocate a new one */
 	p = *vc->vc_uni_pagedir_loc;
+
+	if (!p) {
+		err = -EINVAL;
+
+		goto out_unlock;
+	}
 	
 	if (p->refcount > 1) {
 		int j, k;
@@ -623,6 +629,7 @@ int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list)
 		set_inverse_transl(vc, p, i); /* Update inverse translations */
 	set_inverse_trans_unicode(vc, p);
 
+out_unlock:
 	console_unlock();
 	return err;
 }