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Date: Thu, 18 Sep 2014 14:46:11 +0200
From: Johan Hovold <johan@kernel.org>
To: Octavian Purdila <octavian.purdila@intel.com>
Cc: Johan Hovold <johan@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Linus Walleij <linus.walleij@linaro.org>,
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        lkml <linux-kernel@vger.kernel.org>, linux-gpio@vger.kernel.org,
        linux-i2c@vger.kernel.org
Subject: Re: [PATCH v4 3/3] gpio: add support for the Diolan DLN-2 USB GPIO
 driver
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On Thu, Sep 18, 2014 at 03:43:07PM +0300, Octavian Purdila wrote:
> On Thu, Sep 18, 2014 at 1:54 PM, Johan Hovold <johan@kernel.org> wrote:
> > On Tue, Sep 09, 2014 at 10:24:46PM +0300, Octavian Purdila wrote:

> > Either way, it looks like this could race with get_direction() if you
> > get a set_direction() while get_direction() is retrieving the direction
> > from the device.
> >
> > This would break gpio_get().
> >
> I don't think gpio_set_direction() and gpio_get() are allowed to race.

I wrote that set_direction() and get_direction() could race, which in
turn would break gpio_get() as you would be caching the wrong
direction setting.

But perhaps gpiolib prevents this from happening.

Johan