1 files changed, 21 insertions, 19 deletions

diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c
index 5c6c1bdbd455..8efeae24764f 100644
--- a/drivers/usb/usb-skeleton.c
+++ b/drivers/usb/usb-skeleton.c
@@ -27,6 +27,8 @@
 #define USB_SKEL_VENDOR_ID      0xfff0
 #define USB_SKEL_PRODUCT_ID     0xfff0
 
+static DEFINE_MUTEX(skel_mutex);
+
 /* table of devices that work with this driver */
 static const struct usb_device_id skel_table[] = {
         { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
@@ -60,7 +62,6 @@ struct usb_skel {
         __u8                    bulk_in_endpointAddr;   /* the address of the bulk in endpoint */
         __u8                    bulk_out_endpointAddr;  /* the address of the bulk out endpoint */
         int                     errors;                 /* the last request tanked */
-        int                     open_count;             /* count the number of openers */
         bool                    ongoing_read;           /* a read is going on */
         bool                    processed_urb;          /* indicates we haven't processed the urb */
         spinlock_t              err_lock;               /* lock for errors */
@@ -100,39 +101,37 @@ static int skel_open(struct inode *inode, struct file *file)
                 goto exit;
         }
 
+        mutex_lock(&skel_mutex);
         dev = usb_get_intfdata(interface);
         if (!dev) {
+                mutex_unlock(&skel_mutex);
                 retval = -ENODEV;
                 goto exit;
         }
 
         /* increment our usage count for the device */
         kref_get(&dev->kref);
+        mutex_unlock(&skel_mutex);
 
         /* lock the device to allow correctly handling errors
          * in resumption */
         mutex_lock(&dev->io_mutex);
+        if (!dev->interface) {
+                retval = -ENODEV;
+                goto out_err;
+        }
 
-        if (!dev->open_count++) {
-                retval = usb_autopm_get_interface(interface);
-                        if (retval) {
-                                dev->open_count--;
-                                mutex_unlock(&dev->io_mutex);
-                                kref_put(&dev->kref, skel_delete);
-                                goto exit;
-                        }
-        } /* else { //uncomment this block if you want exclusive open
-                retval = -EBUSY;
-                dev->open_count--;
-                mutex_unlock(&dev->io_mutex);
-                kref_put(&dev->kref, skel_delete);
-                goto exit;
-        } */
-        /* prevent the device from being autosuspended */
+        retval = usb_autopm_get_interface(interface);
+        if (retval)
+                goto out_err;
 
         /* save our object in the file's private structure */
         file->private_data = dev;
+
+out_err:
         mutex_unlock(&dev->io_mutex);
+        if (retval)
+                kref_put(&dev->kref, skel_delete);
 
 exit:
         return retval;
@@ -148,7 +147,7 @@ static int skel_release(struct inode *inode, struct file *file)
 
         /* allow the device to be autosuspended */
         mutex_lock(&dev->io_mutex);
-        if (!--dev->open_count && dev->interface)
+        if (dev->interface)
                 usb_autopm_put_interface(dev->interface);
         mutex_unlock(&dev->io_mutex);
 
@@ -612,7 +611,6 @@ static void skel_disconnect(struct usb_interface *interface)
         int minor = interface->minor;
 
         dev = usb_get_intfdata(interface);
-        usb_set_intfdata(interface, NULL);
 
         /* give back our minor */
         usb_deregister_dev(interface, &skel_class);
@@ -624,8 +622,12 @@ static void skel_disconnect(struct usb_interface *interface)
 
         usb_kill_anchored_urbs(&dev->submitted);
 
+        mutex_lock(&skel_mutex);
+        usb_set_intfdata(interface, NULL);
+
         /* decrement our usage count */
         kref_put(&dev->kref, skel_delete);
+        mutex_unlock(&skel_mutex);
 
         dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
 }