USB: fix autosuspend race in skeleton driver
as the skeleton driver was made ready for autosuspend a race condition
was introduced. The reference to get device must be gotten before the
autosuspend counter is upped, as this operation may sleep, dropping BKL.
Dropping BKL means that the pointer to the device may become invalid.
Here's the fix.
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/usb-skeleton.c b/drivers/usb/usb-skeleton.c
index 296b091..46929a1 100644
--- a/drivers/usb/usb-skeleton.c
+++ b/drivers/usb/usb-skeleton.c
@@ -90,14 +90,16 @@
goto exit;
}
- /* prevent the device from being autosuspended */
- retval = usb_autopm_get_interface(interface);
- if (retval)
- goto exit;
-
/* 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) {
+ kref_put(&dev->kref, skel_delete);
+ goto exit;
+ }
+
/* save our object in the file's private structure */
file->private_data = dev;