1 files changed, 37 insertions, 5 deletions

diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c
index 1b1e669dff9a..59973aecd968 100644
--- a/drivers/usb/usb-skeleton.c
+++ b/drivers/usb/usb-skeleton.c
@@ -57,6 +57,7 @@ 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 */
         spinlock_t              err_lock;               /* lock for errors */
         struct kref             kref;
         struct mutex            io_mutex;               /* synchronize I/O with disconnect */
@@ -101,12 +102,26 @@ static int skel_open(struct inode *inode, struct file *file)
         /* increment our usage count for the device */
         kref_get(&dev->kref);
 
-        /* prevent the device from being autosuspended */
-        retval = usb_autopm_get_interface(interface);
-        if (retval) {
+        /* lock the device to allow correctly handling errors
+         * in resumption */
+        mutex_lock(&dev->io_mutex);
+
+        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 */
 
         /* save our object in the file's private structure */
         file->private_data = dev;
@@ -125,7 +140,7 @@ static int skel_release(struct inode *inode, struct file *file)
 
         /* allow the device to be autosuspended */
         mutex_lock(&dev->io_mutex);
-        if (dev->interface)
+        if (!--dev->open_count && dev->interface)
                 usb_autopm_put_interface(dev->interface);
         mutex_unlock(&dev->io_mutex);
 
@@ -437,10 +452,27 @@ static void skel_draw_down(struct usb_skel *dev)
                 usb_kill_anchored_urbs(&dev->submitted);
 }
 
+static int skel_suspend(struct usb_interface *intf, pm_message_t message)
+{
+        struct usb_skel *dev = usb_get_intfdata(intf);
+
+        if (!dev)
+                return 0;
+        skel_draw_down(dev);
+        return 0;
+}
+
+static int skel_resume (struct usb_interface *intf)
+{
+        return 0;
+}
+
 static struct usb_driver skel_driver = {
         .name =         "skeleton",
         .probe =        skel_probe,
         .disconnect =   skel_disconnect,
+        .suspend =      skel_suspend,
+        .resume =       skel_resume,
         .id_table =     skel_table,
         .supports_autosuspend = 1,
 };