st: cdev lock_kernel() pushdown

Signed-off-by: Jonathan Corbet <corbet@lwn.net>

drivers/scsi/st.c

@@ -38,6 +38,7 @@ static const char *verstr = "20080224";
 #include <linux/cdev.h>
 #include <linux/delay.h>
 #include <linux/mutex.h>
+#include <linux/smp_lock.h>
 
 #include <asm/uaccess.h>
 #include <asm/dma.h>
@@ -1113,7 +1114,7 @@ static int check_tape(struct scsi_tape *STp, struct file *filp)
 }
 
 
-/* Open the device. Needs to be called with BKL only because of incrementing the SCSI host
+/* Open the device. Needs to take the BKL only because of incrementing the SCSI host
    module count. */
 static int st_open(struct inode *inode, struct file *filp)
 {
@@ -1123,15 +1124,18 @@ static int st_open(struct inode *inode, struct file *filp)
 	int dev = TAPE_NR(inode);
 	char *name;
 
+	lock_kernel();
 	/*
 	 * We really want to do nonseekable_open(inode, filp); here, but some
 	 * versions of tar incorrectly call lseek on tapes and bail out if that
 	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
 	 */
 	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
 
-	if (!(STp = scsi_tape_get(dev)))
+	if (!(STp = scsi_tape_get(dev))) {
+		unlock_kernel();
 		return -ENXIO;
+	}
 
 	write_lock(&st_dev_arr_lock);
 	filp->private_data = STp;
@@ -1140,6 +1144,7 @@ static int st_open(struct inode *inode, struct file *filp)
 	if (STp->in_use) {
 		write_unlock(&st_dev_arr_lock);
 		scsi_tape_put(STp);
+		unlock_kernel();
 		DEB( printk(ST_DEB_MSG "%s: Device already in use.\n", name); )
 		return (-EBUSY);
 	}
@@ -1188,12 +1193,14 @@ static int st_open(struct inode *inode, struct file *filp)
 			retval = (-EIO);
 		goto err_out;
 	}
+	unlock_kernel();
 	return 0;
 
  err_out:
 	normalize_buffer(STp->buffer);
 	STp->in_use = 0;
 	scsi_tape_put(STp);
+	unlock_kernel();
 	return retval;
 
 }