TTY/Serial fixes for 4.5-rc2

Here are some small tty/serial driver fixes for 4.5-rc2.
 
 They resolve a number of reported problems (the ioctl one specifically
 has been pointed out by numerous people) and one patch adds some new
 device ids for the 8250_pci driver.  All have been in linux-next
 successfully.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-4.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial fixes from Greg KH:
 "Here are some small tty/serial driver fixes for 4.5-rc2.

  They resolve a number of reported problems (the ioctl one specifically
  has been pointed out by numerous people) and one patch adds some new
  device ids for the 8250_pci driver.  All have been in linux-next
  successfully"

* tag 'tty-4.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  serial: 8250_pci: Add Intel Broadwell ports
  staging/speakup: Use tty_ldisc_ref() for paste kworker
  n_tty: Fix unsafe reference to "other" ldisc
  tty: Fix unsafe ldisc reference via ioctl(TIOCGETD)
  tty: Retry failed reopen if tty teardown in-progress
  tty: Wait interruptibly for tty lock on reopen

drivers/staging/speakup/selection.c

@@ -142,7 +142,9 @@ static void __speakup_paste_selection(struct work_struct *work)
 	struct tty_ldisc *ld;
 	DECLARE_WAITQUEUE(wait, current);
 
-	ld = tty_ldisc_ref_wait(tty);
+	ld = tty_ldisc_ref(tty);
+	if (!ld)
+		goto tty_unref;
 	tty_buffer_lock_exclusive(&vc->port);
 
 	add_wait_queue(&vc->paste_wait, &wait);
@@ -162,6 +164,7 @@ static void __speakup_paste_selection(struct work_struct *work)
 
 	tty_buffer_unlock_exclusive(&vc->port);
 	tty_ldisc_deref(ld);
+tty_unref:
 	tty_kref_put(tty);
 }
 

drivers/tty/n_tty.c

@@ -269,16 +269,13 @@ static void n_tty_check_throttle(struct tty_struct *tty)
 
 static void n_tty_check_unthrottle(struct tty_struct *tty)
 {
-	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
-	    tty->link->ldisc->ops->write_wakeup == n_tty_write_wakeup) {
+	if (tty->driver->type == TTY_DRIVER_TYPE_PTY) {
 		if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE)
 			return;
 		if (!tty->count)
 			return;
 		n_tty_kick_worker(tty);
-		n_tty_write_wakeup(tty->link);
-		if (waitqueue_active(&tty->link->write_wait))
-			wake_up_interruptible_poll(&tty->link->write_wait, POLLOUT);
+		tty_wakeup(tty->link);
 		return;
 	}
 

drivers/tty/serial/8250/8250_pci.c

@@ -1379,6 +1379,9 @@ ce4100_serial_setup(struct serial_private *priv,
 #define PCI_DEVICE_ID_INTEL_BSW_UART1	0x228a
 #define PCI_DEVICE_ID_INTEL_BSW_UART2	0x228c
 
+#define PCI_DEVICE_ID_INTEL_BDW_UART1	0x9ce3
+#define PCI_DEVICE_ID_INTEL_BDW_UART2	0x9ce4
+
 #define BYT_PRV_CLK			0x800
 #define BYT_PRV_CLK_EN			(1 << 0)
 #define BYT_PRV_CLK_M_VAL_SHIFT		1
@@ -1461,11 +1464,13 @@ byt_serial_setup(struct serial_private *priv,
 	switch (pdev->device) {
 	case PCI_DEVICE_ID_INTEL_BYT_UART1:
 	case PCI_DEVICE_ID_INTEL_BSW_UART1:
+	case PCI_DEVICE_ID_INTEL_BDW_UART1:
 		rx_param->src_id = 3;
 		tx_param->dst_id = 2;
 		break;
 	case PCI_DEVICE_ID_INTEL_BYT_UART2:
 	case PCI_DEVICE_ID_INTEL_BSW_UART2:
+	case PCI_DEVICE_ID_INTEL_BDW_UART2:
 		rx_param->src_id = 5;
 		tx_param->dst_id = 4;
 		break;
@@ -2062,6 +2067,20 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = {
 		.subdevice	= PCI_ANY_ID,
 		.setup		= byt_serial_setup,
 	},
+	{
+		.vendor		= PCI_VENDOR_ID_INTEL,
+		.device		= PCI_DEVICE_ID_INTEL_BDW_UART1,
+		.subvendor	= PCI_ANY_ID,
+		.subdevice	= PCI_ANY_ID,
+		.setup		= byt_serial_setup,
+	},
+	{
+		.vendor		= PCI_VENDOR_ID_INTEL,
+		.device		= PCI_DEVICE_ID_INTEL_BDW_UART2,
+		.subvendor	= PCI_ANY_ID,
+		.subdevice	= PCI_ANY_ID,
+		.setup		= byt_serial_setup,
+	},
 	/*
 	 * ITE
 	 */
@@ -5506,6 +5525,16 @@ static struct pci_device_id serial_pci_tbl[] = {
 		PCI_CLASS_COMMUNICATION_SERIAL << 8, 0xff0000,
 		pbn_byt },
 
+	/* Intel Broadwell */
+	{	PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_BDW_UART1,
+		PCI_ANY_ID,  PCI_ANY_ID,
+		PCI_CLASS_COMMUNICATION_SERIAL << 8, 0xff0000,
+		pbn_byt },
+	{	PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_BDW_UART2,
+		PCI_ANY_ID,  PCI_ANY_ID,
+		PCI_CLASS_COMMUNICATION_SERIAL << 8, 0xff0000,
+		pbn_byt },
+
 	/*
 	 * Intel Quark x1000
 	 */

drivers/tty/tty_io.c

@@ -1463,13 +1463,13 @@ static int tty_reopen(struct tty_struct *tty)
 {
 	struct tty_driver *driver = tty->driver;
 
-	if (!tty->count)
-		return -EIO;
-
 	if (driver->type == TTY_DRIVER_TYPE_PTY &&
 	    driver->subtype == PTY_TYPE_MASTER)
 		return -EIO;
 
+	if (!tty->count)
+		return -EAGAIN;
+
 	if (test_bit(TTY_EXCLUSIVE, &tty->flags) && !capable(CAP_SYS_ADMIN))
 		return -EBUSY;
 
@@ -2065,7 +2065,12 @@ static int tty_open(struct inode *inode, struct file *filp)
 
 		if (tty) {
 			mutex_unlock(&tty_mutex);
-			tty_lock(tty);
+			retval = tty_lock_interruptible(tty);
+			if (retval) {
+				if (retval == -EINTR)
+					retval = -ERESTARTSYS;
+				goto err_unref;
+			}
 			/* safe to drop the kref from tty_driver_lookup_tty() */
 			tty_kref_put(tty);
 			retval = tty_reopen(tty);
@@ -2083,7 +2088,11 @@ static int tty_open(struct inode *inode, struct file *filp)
 
 	if (IS_ERR(tty)) {
 		retval = PTR_ERR(tty);
-		goto err_file;
+		if (retval != -EAGAIN || signal_pending(current))
+			goto err_file;
+		tty_free_file(filp);
+		schedule();
+		goto retry_open;
 	}
 
 	tty_add_file(tty, filp);
@@ -2152,6 +2161,7 @@ static int tty_open(struct inode *inode, struct file *filp)
 	return 0;
 err_unlock:
 	mutex_unlock(&tty_mutex);
+err_unref:
 	/* after locks to avoid deadlock */
 	if (!IS_ERR_OR_NULL(driver))
 		tty_driver_kref_put(driver);
@@ -2648,6 +2658,28 @@ static int tiocsetd(struct tty_struct *tty, int __user *p)
 	return ret;
 }
 
+/**
+ *	tiocgetd	-	get line discipline
+ *	@tty: tty device
+ *	@p: pointer to user data
+ *
+ *	Retrieves the line discipline id directly from the ldisc.
+ *
+ *	Locking: waits for ldisc reference (in case the line discipline
+ *		is changing or the tty is being hungup)
+ */
+
+static int tiocgetd(struct tty_struct *tty, int __user *p)
+{
+	struct tty_ldisc *ld;
+	int ret;
+
+	ld = tty_ldisc_ref_wait(tty);
+	ret = put_user(ld->ops->num, p);
+	tty_ldisc_deref(ld);
+	return ret;
+}
+
 /**
  *	send_break	-	performed time break
  *	@tty: device to break on
@@ -2874,7 +2906,7 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	case TIOCGSID:
 		return tiocgsid(tty, real_tty, p);
 	case TIOCGETD:
-		return put_user(tty->ldisc->ops->num, (int __user *)p);
+		return tiocgetd(tty, p);
 	case TIOCSETD:
 		return tiocsetd(tty, p);
 	case TIOCVHANGUP:

drivers/tty/tty_mutex.c

@@ -19,6 +19,14 @@ void __lockfunc tty_lock(struct tty_struct *tty)
 }
 EXPORT_SYMBOL(tty_lock);
 
+int tty_lock_interruptible(struct tty_struct *tty)
+{
+	if (WARN(tty->magic != TTY_MAGIC, "L Bad %p\n", tty))
+		return -EIO;
+	tty_kref_get(tty);
+	return mutex_lock_interruptible(&tty->legacy_mutex);
+}
+
 void __lockfunc tty_unlock(struct tty_struct *tty)
 {
 	if (WARN(tty->magic != TTY_MAGIC, "U Bad %p\n", tty))

include/linux/tty.h

@@ -649,6 +649,7 @@ extern long vt_compat_ioctl(struct tty_struct *tty,
 /* tty_mutex.c */
 /* functions for preparation of BKL removal */
 extern void __lockfunc tty_lock(struct tty_struct *tty);
+extern int  tty_lock_interruptible(struct tty_struct *tty);
 extern void __lockfunc tty_unlock(struct tty_struct *tty);
 extern void __lockfunc tty_lock_slave(struct tty_struct *tty);
 extern void __lockfunc tty_unlock_slave(struct tty_struct *tty);