| From | Andi Kleen <> | Subject | [PATCH] [235/275] USB: uss720 fixup refcount position | Date | Wed, 30 Mar 2011 14:08:01 -0700 (PDT) |
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2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ From: Peter Holik <peter@holik.at>
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> Signed-off-by: Andi Kleen <ak@linux.intel.com>
--- drivers/usb/misc/uss720.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)
Index: linux-2.6.35.y/drivers/usb/misc/uss720.c =================================================================== --- linux-2.6.35.y.orig/drivers/usb/misc/uss720.c 2011-03-29 22:50:20.427735723 -0700 +++ linux-2.6.35.y/drivers/usb/misc/uss720.c 2011-03-29 23:53:41.596473326 -0700 @@ -177,12 +177,11 @@ 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; }
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