From: Peter Holik <peter@holik.at>
Date: Fri, 18 Mar 2011 17:47:44 +0000 (+0100)
Subject: USB: uss720 fixup refcount position
X-Git-Tag: v2.6.27.59~64
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=63d2ae3fad936e870940afa4058dd16c48a1d79e;p=thirdparty%2Fkernel%2Fstable.git

USB: uss720 fixup refcount position

commit adaa3c6342b249548ea830fe8e02aa5b45be8688 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/drivers/usb/misc/uss720.c b/drivers/usb/misc/uss720.c
index e225a95cba801..f4fce0be4e001 100644
--- a/drivers/usb/misc/uss720.c
+++ b/drivers/usb/misc/uss720.c
@@ -176,12 +176,11 @@ 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);
+	kref_get(&rq->ref_count);
 	ret = usb_submit_urb(rq->urb, mem_flags);
-	if (!ret) {
-		kref_get(&rq->ref_count);
+	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;
 }