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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>
hifive-unleashed-5.1
Peter Holik 2011-03-18 18:47:44 +01:00 committed by Greg Kroah-Hartman
parent 45567c28d2
commit adaa3c6342
1 changed files with 3 additions and 4 deletions
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7
drivers/usb/misc/uss720.c
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@ -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);
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;
}