From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932534Ab1DYUZq (ORCPT ); Mon, 25 Apr 2011 16:25:46 -0400 Received: from 1wt.eu ([62.212.114.60]:34618 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932512Ab1DYUZj (ORCPT ); Mon, 25 Apr 2011 16:25:39 -0400 Message-Id: <20110425200237.773652637@pcw.home.local> User-Agent: quilt/0.48-1 Date: Mon, 25 Apr 2011 22:04:22 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@kernel.org, stable-review@kernel.org Cc: Peter Holik , Thomas Sailer , Greg Kroah-Hartman Subject: [PATCH 110/173] USB: uss720 fixup refcount position In-Reply-To: <46075c3a3ef08be6d70339617d6afc98@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.27.59-stable review patch. If anyone has any objections, please let us know. ------------------ From: Peter Holik 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 Acked-by: Thomas Sailer Signed-off-by: Greg Kroah-Hartman --- drivers/usb/misc/uss720.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/drivers/usb/misc/uss720.c +++ b/drivers/usb/misc/uss720.c @@ -176,12 +176,11 @@ static struct uss720_async_request *subm 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; }