Commit adaa3c63 authored Mar 18, 2011 by Peter Holik Committed by Greg Kroah-Hartman Mar 23, 2011

USB: uss720 fixup refcount position



My testprog do a lot of bitbang - after hours i got following warning and my machine lockups:
WARNING: at /build/buildd/linux-2.6.38/lib/kref.c:34
After debugging uss720 driver i discovered that the completion callback was called before
usb_submit_urb returns. The callback frees the request structure that is krefed on return by
usb_submit_urb.

Signed-off-by: Peter Holik <peter@holik.at>
Acked-by: Thomas Sailer <t.sailer@alumni.ethz.ch>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

parent 45567c28

drivers/usb/misc/uss720.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -177,12 +177,11 @@ static struct uss720_async_request *submit_async_request(struct parport_uss720_p
		spin_lock_irqsave(&priv->asynclock, flags);
		list_add_tail(&rq->asynclist, &priv->asynclist);
		spin_unlock_irqrestore(&priv->asynclock, flags);
		ret = usb_submit_urb(rq->urb, mem_flags);
		if (!ret) {
		kref_get(&rq->ref_count);
		ret = usb_submit_urb(rq->urb, mem_flags);
		if (!ret)
		return rq;
		}
		kref_put(&rq->ref_count, destroy_async);
		destroy_async(&rq->ref_count);
		err("submit_async_request submit_urb failed with %d", ret);
		return NULL;
		}