linux-kernel - Re: [PATCH] USB: input: gtco.c: fix usb

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Message-ID: <20140127131741.GB16027@kroah.com>
Date:	Mon, 27 Jan 2014 05:17:41 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	Alexey Khoroshilov <khoroshilov@...ras.ru>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	ldv-project@...uxtesting.org
Subject: Re: [PATCH] USB: input: gtco.c: fix usb_dev leak

On Mon, Jan 27, 2014 at 02:29:23PM +0400, Alexey Khoroshilov wrote:
> On 27.01.2014 10:54, Dmitry Torokhov wrote:
> > Hi Alexey,
> >
> > On Mon, Jan 27, 2014 at 10:31:36AM +0400, Alexey Khoroshilov wrote:
> >> On 21.01.2014 23:59, Dmitry Torokhov wrote:
> >>> On Sun, Jan 19, 2014 at 03:24:26AM +0400, Alexey Khoroshilov wrote:
> >>>> There is usb_get_dev() in gtco_probe(), but there is no usb_put_dev()
> >>>> anywhere in the driver.
> >>>>
> >>>> The patch adds usb_get_dev() to failure handling code of gtco_probe()
> >>>> and to gtco_disconnect(().
> >>> Hmm, I think gtco should simply not use usb_get_dev() in the first
> >>> place.
> >>>
> >>> Thanks.
> >> Dear Dmitry,
> >>
> >> Could you please clarify why usb_get_dev() not needed here?
> >> We store reference to usb_dev in gtco structure, so we should refcount it.
> >> What is wrong in this reasoning?
> > The lifetime of gtco structure is already directly tied to lifetime of
> > usb_dev: when destroying usb_dev driver core will call remove() function
> > of currently bound driver (in our case gtco) which will destroy gtco
> > memory.
> >
> > Taking additional reference is not needed here.
> >
> > Hope this helps.
> Thank you, that helps a lot.
> 
> By the way, usb_skeleton suggests to use usb_get_dev()/usb_put_dev()
> nevertheless.
> 
> Greg, may be it makes sense to fix usb_skeleton as well?

Patches are always welcome.
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