1 files changed, 10 insertions, 2 deletions

diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c
index 962b28cd3a79..8432bf171d2e 100644
--- a/drivers/usb/usb-skeleton.c
+++ b/drivers/usb/usb-skeleton.c
@@ -34,6 +34,9 @@ static struct usb_device_id skel_table [] = {
 };
 MODULE_DEVICE_TABLE(usb, skel_table);
 
+/* to prevent a race between open and disconnect */
+static DEFINE_MUTEX(skel_open_lock);
+
 
 /* Get a minor range for your devices from the usb maintainer */
 #define USB_SKEL_MINOR_BASE     192
@@ -80,8 +83,10 @@ static int skel_open(struct inode *inode, struct file *file)
 
         subminor = iminor(inode);
 
+        mutex_lock(&skel_open_lock);
         interface = usb_find_interface(&skel_driver, subminor);
         if (!interface) {
+                mutex_unlock(&skel_open_lock);
                 err ("%s - error, can't find device for minor %d",
                      __FUNCTION__, subminor);
                 retval = -ENODEV;
@@ -90,12 +95,15 @@ static int skel_open(struct inode *inode, struct file *file)
 
         dev = usb_get_intfdata(interface);
         if (!dev) {
+                mutex_unlock(&skel_open_lock);
                 retval = -ENODEV;
                 goto exit;
         }
 
         /* increment our usage count for the device */
         kref_get(&dev->kref);
+        /* now we can drop the lock */
+        mutex_unlock(&skel_open_lock);
 
         /* prevent the device from being autosuspended */
         retval = usb_autopm_get_interface(interface);
@@ -361,14 +369,14 @@ static void skel_disconnect(struct usb_interface *interface)
         int minor = interface->minor;
 
         /* prevent skel_open() from racing skel_disconnect() */
-        lock_kernel();
+        mutex_lock(&skel_open_lock);
 
         dev = usb_get_intfdata(interface);
         usb_set_intfdata(interface, NULL);
 
         /* give back our minor */
         usb_deregister_dev(interface, &skel_class);
-        unlock_kernel();
+        mutex_unlock(&skel_open_lock);
 
         /* prevent more I/O from starting */
         mutex_lock(&dev->io_mutex);