From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johan Hovold Subject: Re: [PATCH v4 3/3] gpio: add support for the Diolan DLN-2 USB GPIO driver Date: Thu, 18 Sep 2014 14:46:11 +0200 Message-ID: <20140918124611.GA26817@localhost> References: <1410290686-6680-1-git-send-email-octavian.purdila@intel.com> <1410290686-6680-4-git-send-email-octavian.purdila@intel.com> <20140918105458.GA2337@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-lb0-f178.google.com ([209.85.217.178]:63600 "EHLO mail-lb0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751294AbaIRMsh (ORCPT ); Thu, 18 Sep 2014 08:48:37 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-gpio-owner@vger.kernel.org List-Id: linux-gpio@vger.kernel.org To: Octavian Purdila Cc: Johan Hovold , Greg Kroah-Hartman , Linus Walleij , Alexandre Courbot , wsa@the-dreams.de, Samuel Ortiz , Lee Jones , Arnd Bergmann , Daniel Baluta , Laurentiu Palcu , linux-usb@vger.kernel.org, lkml , linux-gpio@vger.kernel.org, linux-i2c@vger.kernel.org On Thu, Sep 18, 2014 at 03:43:07PM +0300, Octavian Purdila wrote: > On Thu, Sep 18, 2014 at 1:54 PM, Johan Hovold 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