1 files changed, 39 insertions, 11 deletions

diff --git a/drivers/usb/class/usblp.c b/drivers/usb/class/usblp.c
index 5e456a83779d..f69a0a0b7266 100644
--- a/drivers/usb/class/usblp.c
+++ b/drivers/usb/class/usblp.c
@@ -289,8 +289,25 @@ static int usblp_ctrl_msg(struct usblp *usblp, int request, int type, int dir, i
 #define usblp_reset(usblp)\
 	usblp_ctrl_msg(usblp, USBLP_REQ_RESET, USB_TYPE_CLASS, USB_DIR_OUT, USB_RECIP_OTHER, 0, NULL, 0)
 
-#define usblp_hp_channel_change_request(usblp, channel, buffer) \
-	usblp_ctrl_msg(usblp, USBLP_REQ_HP_CHANNEL_CHANGE_REQUEST, USB_TYPE_VENDOR, USB_DIR_IN, USB_RECIP_INTERFACE, channel, buffer, 1)
+static int usblp_hp_channel_change_request(struct usblp *usblp, int channel, u8 *new_channel)
+{
+	u8 *buf;
+	int ret;
+
+	buf = kzalloc(1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = usblp_ctrl_msg(usblp, USBLP_REQ_HP_CHANNEL_CHANGE_REQUEST,
+			USB_TYPE_VENDOR, USB_DIR_IN, USB_RECIP_INTERFACE,
+			channel, buf, 1);
+	if (ret == 0)
+		*new_channel = buf[0];
+
+	kfree(buf);
+
+	return ret;
+}
 
 /*
  * See the description for usblp_select_alts() below for the usage
@@ -481,7 +498,8 @@ static int usblp_release(struct inode *inode, struct file *file)
 	usb_autopm_put_interface(usblp->intf);
 
 	if (!usblp->present)		/* finish cleanup from disconnect */
-		usblp_cleanup(usblp);
+		usblp_cleanup(usblp);	/* any URBs must be dead */
+
 	mutex_unlock(&usblp_mutex);
 	return 0;
 }
@@ -839,6 +857,11 @@ static ssize_t usblp_read(struct file *file, char __user *buffer, size_t len, lo
 	if (rv < 0)
 		return rv;
 
+	if (!usblp->present) {
+		count = -ENODEV;
+		goto done;
+	}
+
 	if ((avail = usblp->rstatus) < 0) {
 		printk(KERN_ERR "usblp%d: error %d reading from printer\n",
 		    usblp->minor, (int)avail);
@@ -1317,14 +1340,17 @@ static int usblp_set_protocol(struct usblp *usblp, int protocol)
 	if (protocol < USBLP_FIRST_PROTOCOL || protocol > USBLP_LAST_PROTOCOL)
 		return -EINVAL;
 
-	alts = usblp->protocol[protocol].alt_setting;
-	if (alts < 0)
-		return -EINVAL;
-	r = usb_set_interface(usblp->dev, usblp->ifnum, alts);
-	if (r < 0) {
-		printk(KERN_ERR "usblp: can't set desired altsetting %d on interface %d\n",
-			alts, usblp->ifnum);
-		return r;
+	/* Don't unnecessarily set the interface if there's a single alt. */
+	if (usblp->intf->num_altsetting > 1) {
+		alts = usblp->protocol[protocol].alt_setting;
+		if (alts < 0)
+			return -EINVAL;
+		r = usb_set_interface(usblp->dev, usblp->ifnum, alts);
+		if (r < 0) {
+			printk(KERN_ERR "usblp: can't set desired altsetting %d on interface %d\n",
+				alts, usblp->ifnum);
+			return r;
+		}
 	}
 
 	usblp->bidir = (usblp->protocol[protocol].epread != NULL);
@@ -1388,9 +1414,11 @@ static void usblp_disconnect(struct usb_interface *intf)
 
 	usblp_unlink_urbs(usblp);
 	mutex_unlock(&usblp->mut);
+	usb_poison_anchored_urbs(&usblp->urbs);
 
 	if (!usblp->used)
 		usblp_cleanup(usblp);
+
 	mutex_unlock(&usblp_mutex);
 }