TTY: fix for tty operations bugs

This is fixed with the recent tty operations rewrite in mainline in a
different way, this is a selective backport of the relevant portions to
the -stable tree.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

8 files changed, 37 insertions, 10 deletions

diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c
index 0a9b75139e0f..756e1bb04253 100644
--- a/drivers/net/hamradio/6pack.c
+++ b/drivers/net/hamradio/6pack.c
@@ -601,6 +601,8 @@ static int sixpack_open(struct tty_struct *tty)
 
 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
+	if (!tty->driver->write)
+		return -EOPNOTSUPP;
 
 	dev = alloc_netdev(sizeof(struct sixpack), "sp%d", sp_setup);
 	if (!dev) {
diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c
index 30c9b3b0d131..f650da30ece8 100644
--- a/drivers/net/hamradio/mkiss.c
+++ b/drivers/net/hamradio/mkiss.c
@@ -529,6 +529,7 @@ static void ax_encaps(struct net_device *dev, unsigned char *icp, int len)
 static int ax_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct mkiss *ax = netdev_priv(dev);
+	int cib = 0;
 
 	if (!netif_running(dev))  {
 		printk(KERN_ERR "mkiss: %s: xmit call when iface is down\n", dev->name);
@@ -544,10 +545,11 @@ static int ax_xmit(struct sk_buff *skb, struct net_device *dev)
 			/* 20 sec timeout not reached */
 			return 1;
 		}
+		if (ax->tty->driver->chars_in_buffer)
+			cib = ax->tty->driver->chars_in_buffer(ax->tty);
 
 		printk(KERN_ERR "mkiss: %s: transmit timed out, %s?\n", dev->name,
-		       (ax->tty->driver->chars_in_buffer(ax->tty) || ax->xleft) ?
-		       "bad line quality" : "driver error");
+		     cib || ax->xleft ? "bad line quality" : "driver error");
 
 		ax->xleft = 0;
 		clear_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags);
@@ -736,6 +738,8 @@ static int mkiss_open(struct tty_struct *tty)
 
 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
+	if (!tty->driver->write)
+		return -EOPNOTSUPP;
 
 	dev = alloc_netdev(sizeof(struct mkiss), "ax%d", ax_setup);
 	if (!dev) {
diff --git a/drivers/net/irda/irtty-sir.c b/drivers/net/irda/irtty-sir.c
index fc753d7f674e..df755f501e67 100644
--- a/drivers/net/irda/irtty-sir.c
+++ b/drivers/net/irda/irtty-sir.c
@@ -64,7 +64,9 @@ static int irtty_chars_in_buffer(struct sir_dev *dev)
 	IRDA_ASSERT(priv != NULL, return -1;);
 	IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);
 
-	return priv->tty->driver->chars_in_buffer(priv->tty);
+	if (priv->tty->driver->chars_in_buffer)
+		return priv->tty->driver->chars_in_buffer(priv->tty);
+	return 0;
 }
 
 /* Wait (sleep) until underlaying hardware finished transmission
diff --git a/drivers/net/ppp_async.c b/drivers/net/ppp_async.c
index f023d5b67e6e..098bf441b376 100644
--- a/drivers/net/ppp_async.c
+++ b/drivers/net/ppp_async.c
@@ -158,6 +158,9 @@ ppp_asynctty_open(struct tty_struct *tty)
 	struct asyncppp *ap;
 	int err;
 
+	if (!tty->driver->write)
+		return -EOPNOTSUPP;
+
 	err = -ENOMEM;
 	ap = kzalloc(sizeof(*ap), GFP_KERNEL);
 	if (!ap)
diff --git a/drivers/net/ppp_synctty.c b/drivers/net/ppp_synctty.c
index 0d80fa546719..73729383e976 100644
--- a/drivers/net/ppp_synctty.c
+++ b/drivers/net/ppp_synctty.c
@@ -207,6 +207,9 @@ ppp_sync_open(struct tty_struct *tty)
 	struct syncppp *ap;
 	int err;
 
+	if (!tty->driver->write)
+		return -EOPNOTSUPP;
+
 	ap = kzalloc(sizeof(*ap), GFP_KERNEL);
 	err = -ENOMEM;
 	if (!ap)
diff --git a/drivers/net/slip.c b/drivers/net/slip.c
index 5a55ede352f4..9d138bf021a6 100644
--- a/drivers/net/slip.c
+++ b/drivers/net/slip.c
@@ -460,10 +460,14 @@ static void sl_tx_timeout(struct net_device *dev)
 			/* 20 sec timeout not reached */
 			goto out;
 		}
-		printk(KERN_WARNING "%s: transmit timed out, %s?\n",
-			dev->name,
-			(sl->tty->driver->chars_in_buffer(sl->tty) || sl->xleft) ?
-				"bad line quality" : "driver error");
+		{
+			int cib = 0;
+			if (sl->tty->driver->chars_in_buffer)
+				cib = sl->tty->driver->chars_in_buffer(sl->tty);
+			printk(KERN_WARNING "%s: transmit timed out, %s?\n",
+				dev->name, (cib || sl->xleft) ?
+				       "bad line quality" : "driver error");
+		}
 		sl->xleft = 0;
 		sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
 		sl_unlock(sl);
@@ -829,6 +833,8 @@ static int slip_open(struct tty_struct *tty)
 
 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
+	if (!tty->driver->write)
+		return -EOPNOTSUPP;
 
 	/* RTnetlink lock is misused here to serialize concurrent
 	   opens of slip channels. There are better ways, but it is
diff --git a/drivers/net/wan/x25_asy.c b/drivers/net/wan/x25_asy.c
index 0f8aca8a4d43..f5b9a7124111 100644
--- a/drivers/net/wan/x25_asy.c
+++ b/drivers/net/wan/x25_asy.c
@@ -283,6 +283,10 @@ static void x25_asy_write_wakeup(struct tty_struct *tty)
 static void x25_asy_timeout(struct net_device *dev)
 {
 	struct x25_asy *sl = (struct x25_asy*)(dev->priv);
+	int cib = 0;
+
+	if (sl->tty->driver->chars_in_buffer)
+		cib = sl->tty->driver->chars_in_buffer(sl->tty);
 
 	spin_lock(&sl->lock);
 	if (netif_queue_stopped(dev)) {
@@ -290,8 +294,7 @@ static void x25_asy_timeout(struct net_device *dev)
 		 *      14 Oct 1994 Dmitry Gorodchanin.
 		 */
 		printk(KERN_WARNING "%s: transmit timed out, %s?\n", dev->name,
-		       (sl->tty->driver->chars_in_buffer(sl->tty) || sl->xleft) ?
-		       "bad line quality" : "driver error");
+		       (cib || sl->xleft) ? "bad line quality" : "driver error");
 		sl->xleft = 0;
 		sl->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
 		x25_asy_unlock(sl);
@@ -561,6 +564,9 @@ static int x25_asy_open_tty(struct tty_struct *tty)
 		return -EEXIST;
 	}
 
+	if (!tty->driver->write)
+		return -EOPNOTSUPP;
+
 	/* OK.  Find a free X.25 channel to use. */
 	if ((sl = x25_asy_alloc()) == NULL) {
 		return -ENFILE;
diff --git a/drivers/net/wireless/strip.c b/drivers/net/wireless/strip.c
index 88efe1bae58f..5536a9493e21 100644
--- a/drivers/net/wireless/strip.c
+++ b/drivers/net/wireless/strip.c
@@ -802,7 +802,8 @@ static void set_baud(struct tty_struct *tty, unsigned int baudcode)
 	struct ktermios old_termios = *(tty->termios);
 	tty->termios->c_cflag &= ~CBAUD;	/* Clear the old baud setting */
 	tty->termios->c_cflag |= baudcode;	/* Set the new baud setting */
-	tty->driver->set_termios(tty, &old_termios);
+	if (tty->driver->set_termios)
+		tty->driver->set_termios(tty, &old_termios);
 }
 
 /*