From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Mack <daniel@zonque.org>
Subject: Re: [PATCH v3 2/2] cap11xx: add LED support
Date: Mon, 15 Jun 2015 11:03:09 +0200
Message-ID: <557E94CD.30705@zonque.org>
References: <1434169054-11035-1-git-send-email-mranostay@gmail.com>	<1434169054-11035-3-git-send-email-mranostay@gmail.com>	<557E8997.7070100@samsung.com> <CAKzfze8E-22XxzGuMUJWhcpmdoA=63XWR-v+bpf+Cdn70VoJqA@mail.gmail.com>
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To: Matt Ranostay <mranostay@gmail.com>, Jacek Anaszewski <j.anaszewski@samsung.com>
Cc: Daniel Mack <zonque@gmail.com>, Dmitry Torokhov <dmitry.torokhov@gmail.com>, "linux-input@vger.kernel.org" <linux-input@vger.kernel.org>, linux-leds@vger.kernel.org, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
List-Id: devicetree@vger.kernel.org

On 06/15/2015 10:56 AM, Matt Ranostay wrote:
> On Mon, Jun 15, 2015 at 1:15 AM, Jacek Anaszewski
> <j.anaszewski@samsung.com> wrote:

>>> +               error = devm_led_classdev_register(dev, &led->cdev);
>>> +               if (error < 0)
>>> +                       return -EINVAL;
>>> +               INIT_WORK(&led->work, cap11xx_led_work);
>>> +               schedule_work(&led->work);
>>
>>
>> Work queue should be initialized before registration of the LED class
>> device.
> What is the reason for this? Just curious

It's a race condition. The LED device is accessible once
devm_led_classdev_register() returns. So a user could be calling into
cap11xx_led_set() before the work queue is initialized, which would
hence access a NULL pointer.


Daniel