linux-kernel - Re: [PATCH 2/2] gpiolib: Fix unaligned used of reference counters

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Message-ID: <CACRpkdak7ZT7fyVpfZB26m7xshJssV-8dxNWjOE22j6L2EUO0w@mail.gmail.com>
Date:	Wed, 8 Jun 2016 10:41:37 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Roger Quadros <rogerq@...com>
Cc:	Alexandre Courbot <gnurou@...il.com>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] gpiolib: Fix unaligned used of reference counters

On Fri, Jun 3, 2016 at 7:10 PM, Ricardo Ribalda Delgado
<ricardo.ribalda@...il.com> wrote:

> gpiolib relies on the reference counters to clean up the gpio_device
> structure.
>
> Although the number of get/put is properly aligned on gpiolib.c
> itself, it does not take into consideration how the referece counters
> are affected by other external functions such as cdev_add and device_add.
>
> Because of this, after the last call to put_device, the reference counter
> has a value of +3, therefore never calling gpiodevice_release.
>
> Due to the fact that some of the device  has already been cleaned on
> gpiochip_remove, the library will end up OOPsing the kernel (e.g. a call
> to of_gpiochip_find_and_xlate).
>
> Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>

Again, thanks for fixing my stupid mistakes.

Applied and tagged for stable.

Yours,
Linus Walleij