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path: root/drivers/usb/misc/legousbtower.c
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Diffstat (limited to 'drivers/usb/misc/legousbtower.c')
-rw-r--r--drivers/usb/misc/legousbtower.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/drivers/usb/misc/legousbtower.c b/drivers/usb/misc/legousbtower.c
index 561970b889a..aab320085eb 100644
--- a/drivers/usb/misc/legousbtower.c
+++ b/drivers/usb/misc/legousbtower.c
@@ -198,6 +198,7 @@ static struct usb_device_id tower_table [] = {
};
MODULE_DEVICE_TABLE (usb, tower_table);
+static DEFINE_MUTEX(open_disc_mutex);
#define LEGO_USB_TOWER_MINOR_BASE 160
@@ -350,25 +351,31 @@ static int tower_open (struct inode *inode, struct file *file)
goto exit;
}
+ mutex_lock(&open_disc_mutex);
dev = usb_get_intfdata(interface);
if (!dev) {
+ mutex_unlock(&open_disc_mutex);
retval = -ENODEV;
goto exit;
}
/* lock this device */
if (down_interruptible (&dev->sem)) {
+ mutex_unlock(&open_disc_mutex);
retval = -ERESTARTSYS;
goto exit;
}
+
/* allow opening only once */
if (dev->open_count) {
+ mutex_unlock(&open_disc_mutex);
retval = -EBUSY;
goto unlock_exit;
}
dev->open_count = 1;
+ mutex_unlock(&open_disc_mutex);
/* reset the tower */
result = usb_control_msg (dev->udev,
@@ -437,9 +444,10 @@ static int tower_release (struct inode *inode, struct file *file)
if (dev == NULL) {
dbg(1, "%s: object is NULL", __FUNCTION__);
retval = -ENODEV;
- goto exit;
+ goto exit_nolock;
}
+ mutex_lock(&open_disc_mutex);
if (down_interruptible (&dev->sem)) {
retval = -ERESTARTSYS;
goto exit;
@@ -468,6 +476,8 @@ unlock_exit:
up (&dev->sem);
exit:
+ mutex_unlock(&open_disc_mutex);
+exit_nolock:
dbg(2, "%s: leave, return value %d", __FUNCTION__, retval);
return retval;
}
@@ -989,6 +999,7 @@ static void tower_disconnect (struct usb_interface *interface)
dbg(2, "%s: enter", __FUNCTION__);
dev = usb_get_intfdata (interface);
+ mutex_lock(&open_disc_mutex);
usb_set_intfdata (interface, NULL);
minor = dev->minor;
@@ -997,6 +1008,7 @@ static void tower_disconnect (struct usb_interface *interface)
usb_deregister_dev (interface, &tower_class);
down (&dev->sem);
+ mutex_unlock(&open_disc_mutex);
/* if the device is not opened, then we clean up right now */
if (!dev->open_count) {