USB: mutexification of usblp

this patch:
- converts usblp fully to mutex
- makes sleeping interruptible where EINTR can be returned anyway

Signed-off-by: Oliver Neukum <oliver@neukum.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/class/usblp.c

@@ -130,7 +130,7 @@ MFG:HEWLETT-PACKARD;MDL:DESKJET 970C;CMD:MLC,PCL,PML;CLASS:PRINTER;DESCRIPTION:H
 
 struct usblp {
 	struct usb_device 	*dev;			/* USB device */
-	struct semaphore	sem;			/* locks this struct, especially "dev" */
+	struct mutex		mut;			/* locks this struct, especially "dev" */
 	char			*writebuf;		/* write transfer_buffer */
 	char			*readbuf;		/* read transfer_buffer */
 	char			*statusbuf;		/* status transfer_buffer */
@@ -465,7 +465,7 @@ static long usblp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	int twoints[2];
 	int retval = 0;
 
-	down (&usblp->sem);
+	mutex_lock (&usblp->mut);
 	if (!usblp->present) {
 		retval = -ENODEV;
 		goto done;
@@ -644,14 +644,14 @@ static long usblp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 		}
 
 done:
-	up (&usblp->sem);
+	mutex_unlock (&usblp->mut);
 	return retval;
 }
 
 static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
 {
 	struct usblp *usblp = file->private_data;
-	int timeout, rv, err = 0, transfer_length = 0;
+	int timeout, intr, rv, err = 0, transfer_length = 0;
 	size_t writecount = 0;
 
 	while (writecount < count) {
@@ -668,14 +668,16 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
 			if (rv < 0)
 				return writecount ? writecount : -EINTR;
 		}
-		down (&usblp->sem);
+		intr = mutex_lock_interruptible (&usblp->mut);
+		if (intr)
+			return writecount ? writecount : -EINTR;
 		if (!usblp->present) {
-			up (&usblp->sem);
+			mutex_unlock (&usblp->mut);
 			return -ENODEV;
 		}
 
 		if (usblp->sleeping) {
-			up (&usblp->sem);
+			mutex_unlock (&usblp->mut);
 			return writecount ? writecount : -ENODEV;
 		}
 
@@ -687,10 +689,10 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
 				err = usblp->writeurb->status;
 			} else
 				err = usblp_check_status(usblp, err);
-			up (&usblp->sem);
+			mutex_unlock (&usblp->mut);
 
 			/* if the fault was due to disconnect, let khubd's
-			 * call to usblp_disconnect() grab usblp->sem ...
+			 * call to usblp_disconnect() grab usblp->mut ...
 			 */
 			schedule ();
 			continue;
@@ -702,7 +704,7 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
 		 */
 		writecount += transfer_length;
 		if (writecount == count) {
-			up(&usblp->sem);
+			mutex_unlock(&usblp->mut);
 			break;
 		}
 
@@ -714,7 +716,7 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
 
 		if (copy_from_user(usblp->writeurb->transfer_buffer, 
 				   buffer + writecount, transfer_length)) {
-			up(&usblp->sem);
+			mutex_unlock(&usblp->mut);
 			return writecount ? writecount : -EFAULT;
 		}
 
@@ -727,10 +729,10 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
 				count = -EIO;
 			else
 				count = writecount ? writecount : -ENOMEM;
-			up (&usblp->sem);
+			mutex_unlock (&usblp->mut);
 			break;
 		}
-		up (&usblp->sem);
+		mutex_unlock (&usblp->mut);
 	}
 
 	return count;
@@ -739,12 +741,14 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
 static ssize_t usblp_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
 {
 	struct usblp *usblp = file->private_data;
-	int rv;
+	int rv, intr;
 
 	if (!usblp->bidir)
 		return -EINVAL;
 
-	down (&usblp->sem);
+	intr = mutex_lock_interruptible (&usblp->mut);
+	if (intr)
+		return -EINTR;
 	if (!usblp->present) {
 		count = -ENODEV;
 		goto done;
@@ -757,9 +761,9 @@ static ssize_t usblp_read(struct file *file, char __user *buffer, size_t count,
 			count = -EAGAIN;
 			goto done;
 		}
-		up(&usblp->sem);
+		mutex_unlock(&usblp->mut);
 		rv = wait_event_interruptible(usblp->wait, usblp->rcomplete || !usblp->present);
-		down(&usblp->sem);
+		mutex_lock(&usblp->mut);
 		if (rv < 0) {
 			count = -EINTR;
 			goto done;
@@ -807,7 +811,7 @@ static ssize_t usblp_read(struct file *file, char __user *buffer, size_t count,
 	}
 
 done:
-	up (&usblp->sem);
+	mutex_unlock (&usblp->mut);
 	return count;
 }
 
@@ -886,7 +890,7 @@ static int usblp_probe(struct usb_interface *intf,
 		goto abort;
 	}
 	usblp->dev = dev;
-	init_MUTEX (&usblp->sem);
+	mutex_init (&usblp->mut);
 	init_waitqueue_head(&usblp->wait);
 	usblp->ifnum = intf->cur_altsetting->desc.bInterfaceNumber;
 	usblp->intf = intf;
@@ -1178,7 +1182,7 @@ static void usblp_disconnect(struct usb_interface *intf)
 	device_remove_file(&intf->dev, &dev_attr_ieee1284_id);
 
 	mutex_lock (&usblp_mutex);
-	down (&usblp->sem);
+	mutex_lock (&usblp->mut);
 	usblp->present = 0;
 	usb_set_intfdata (intf, NULL);
 
@@ -1187,7 +1191,7 @@ static void usblp_disconnect(struct usb_interface *intf)
 			usblp->writebuf, usblp->writeurb->transfer_dma);
 	usb_buffer_free (usblp->dev, USBLP_BUF_SIZE,
 			usblp->readbuf, usblp->readurb->transfer_dma);
-	up (&usblp->sem);
+	mutex_unlock (&usblp->mut);
 
 	if (!usblp->used)
 		usblp_cleanup (usblp);
@@ -1200,11 +1204,11 @@ static int usblp_suspend (struct usb_interface *intf, pm_message_t message)
 
 	/* this races against normal access and open */
 	mutex_lock (&usblp_mutex);
-	down (&usblp->sem);
+	mutex_lock (&usblp->mut);
 	/* we take no more IO */
 	usblp->sleeping = 1;
 	usblp_unlink_urbs(usblp);
-	up (&usblp->sem);
+	mutex_unlock (&usblp->mut);
 	mutex_unlock (&usblp_mutex);
 
 	return 0;
@@ -1216,12 +1220,12 @@ static int usblp_resume (struct usb_interface *intf)
 	int r;
 
 	mutex_lock (&usblp_mutex);
-	down (&usblp->sem);
+	mutex_lock (&usblp->mut);
 
 	usblp->sleeping = 0;
 	r = handle_bidir (usblp);
 
-	up (&usblp->sem);
+	mutex_unlock (&usblp->mut);
 	mutex_unlock (&usblp_mutex);
 
 	return r;