| From | Paul Gortmaker <> | Subject | [34-longterm 214/247] USB: uss720 fixup refcount position | Date | Thu, 23 Jun 2011 13:34:42 -0400 |
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From: Peter Holik <peter@holik.at>
------------------- This is a commit scheduled for the next v2.6.34 longterm release. If you see a problem with using this for longterm, please comment. -------------------
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: Paul Gortmaker <paul.gortmaker@windriver.com> --- drivers/usb/misc/uss720.c | 7 +++---- 1 files changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/misc/uss720.c b/drivers/usb/misc/uss720.c index 4ff2158..9727daa 100644 --- a/drivers/usb/misc/uss720.c +++ b/drivers/usb/misc/uss720.c @@ -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; } -- 1.7.4.4
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