[SCSI] st: Use mutex instead of semaphore

The SCSI Tape driver uses a semaphore as mutex. Use the mutex API
instead of the (binary) semaphore.
Signed-off-by: NMatthias Kaehlcke <matthias.kaehlcke@gmail.com>
Acked-by: NKai Makisara <kai.makisara@kolumbus.fi>
Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/st.c

@@ -1485,7 +1485,7 @@ st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
 	struct st_buffer *STbp;
 	char *name = tape_name(STp);
 
-	if (down_interruptible(&STp->lock))
+	if (mutex_lock_interruptible(&STp->lock))
 		return -ERESTARTSYS;
 
 	retval = rw_checks(STp, filp, count);
@@ -1736,7 +1736,7 @@ st_write(struct file *filp, const char __user *buf, size_t count, loff_t * ppos)
 	if (SRpnt != NULL)
 		st_release_request(SRpnt);
 	release_buffering(STp, 0);
-	up(&STp->lock);
+	mutex_unlock(&STp->lock);
 
 	return retval;
 }
@@ -1942,7 +1942,7 @@ st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
 	struct st_buffer *STbp = STp->buffer;
 	DEB( char *name = tape_name(STp); )
 
-	if (down_interruptible(&STp->lock))
+	if (mutex_lock_interruptible(&STp->lock))
 		return -ERESTARTSYS;
 
 	retval = rw_checks(STp, filp, count);
@@ -2069,7 +2069,7 @@ st_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos)
 		release_buffering(STp, 1);
 		STbp->buffer_bytes = 0;
 	}
-	up(&STp->lock);
+	mutex_unlock(&STp->lock);
 
 	return retval;
 }
@@ -3226,7 +3226,7 @@ static int st_ioctl(struct inode *inode, struct file *file,
 	char *name = tape_name(STp);
 	void __user *p = (void __user *)arg;
 
-	if (down_interruptible(&STp->lock))
+	if (mutex_lock_interruptible(&STp->lock))
 		return -ERESTARTSYS;
 
         DEB(
@@ -3537,7 +3537,7 @@ static int st_ioctl(struct inode *inode, struct file *file,
 			retval = (-EFAULT);
 		goto out;
 	}
-	up(&STp->lock);
+	mutex_unlock(&STp->lock);
 	switch (cmd_in) {
 		case SCSI_IOCTL_GET_IDLUN:
 		case SCSI_IOCTL_GET_BUS_NUMBER:
@@ -3563,7 +3563,7 @@ static int st_ioctl(struct inode *inode, struct file *file,
 	return retval;
 
  out:
-	up(&STp->lock);
+	mutex_unlock(&STp->lock);
 	return retval;
 }
 
@@ -4029,7 +4029,7 @@ static int st_probe(struct device *dev)
 
 	tpnt->density_changed = tpnt->compression_changed =
 	    tpnt->blksize_changed = 0;
-	init_MUTEX(&tpnt->lock);
+	mutex_init(&tpnt->lock);
 
 	st_nr_dev++;
 	write_unlock(&st_dev_arr_lock);

drivers/scsi/st.h

@@ -3,6 +3,7 @@
 #define _ST_H
 
 #include <linux/completion.h>
+#include <linux/mutex.h>
 #include <linux/kref.h>
 #include <scsi/scsi_cmnd.h>
 
@@ -98,7 +99,7 @@ struct st_partstat {
 struct scsi_tape {
 	struct scsi_driver *driver;
 	struct scsi_device *device;
-	struct semaphore lock;	/* For serialization */
+	struct mutex lock;	/* For serialization */
 	struct completion wait;	/* For SCSI commands */
 	struct st_buffer *buffer;