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Subject: Re: [PATCH v2] staging: bcm2835-audio: Release resources on
 module_exit()
To:     Andy Shevchenko <andy.shevchenko@gmail.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Eric Anholt <eric@anholt.net>,
        Stefan Wahren <stefan.wahren@i2se.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Ray Jui <rjui@broadcom.com>,
        Scott Branden <sbranden@broadcom.com>,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@broadcom.com>,
        Michael Zoran <mzoran@crowfest.net>,
        linux-rpi-kernel@lists.infradead.org,
        linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
        devel@driverdev.osuosl.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
References: <63ee611d-9fd7-a67a-45aa-229cc4a83ed2@gmail.com>
 <20180313193414.11535-1-k.marinushkin@gmail.com>
 <CAHp75Ve9MRAgSu74Mzr2defd84umyeKpfvX51-Qhk4SvLx3Qng@mail.gmail.com>
 <1a59a938-0381-49f4-dfd9-c7a52bdb0eae@gmail.com>
 <CAHp75Vfwpwcc6_somOcSMYwmBhnkSwR7vn2piAZwA1GFkGAJRw@mail.gmail.com>
From:   Kirill Marinushkin <k.marinushkin@gmail.com>
Message-ID: <15cc84cc-a887-7473-d64c-00c23e930e0d@gmail.com>
Date:   Wed, 21 Mar 2018 17:58:06 +0100
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On 03/21/18 16:03, Andy Shevchenko wrote:
> On Thu, Mar 15, 2018 at 7:57 AM, Kirill Marinushkin
> <k.marinushkin@gmail.com> wrote:
>> On 03/13/18 22:23, Andy Shevchenko wrote:
>>> On Tue, Mar 13, 2018 at 9:34 PM, Kirill Marinushkin
>>> <k.marinushkin@gmail.com> wrote:
>>>> In the current implementation, `rmmod snd_bcm2835` does not release
>>>> resources properly. It causes an oops when trying to list sound devices.
>>>>
>>>> This commit fixes it.
>>> Nice catch!
>>>
>>> See my comments below.
>>>
>>>>  static void snd_devm_unregister_child(struct device *dev, void *res)
>>>>  {
>>>>         struct device *childdev = *(struct device **)res;
>>>> +       struct bcm2835_chip *chip = dev_get_drvdata(childdev);
>>>> +       struct snd_card *card = chip->card;
>>>> +
>>>> +       snd_card_free(card);
>>>> +       dev_set_drvdata(childdev, NULL);
>>> AFAIU this is done by device core.
>> Maybe you are right. But I don't know, which function in the device core does it.
>> It is safe to have this line. So, I suggest to keep it.
> Please, remove.
> If you don't know, perhaps you need to spend more time on doing homework?

You are right, I actually should pay more attention to this detail.
I will remove this line and send as a patch v3

> % git grep -n -w dev_set_drvdata -- drivers/base/dd.c
> drivers/base/dd.c:469:          dev_set_drvdata(dev, NULL);
> drivers/base/dd.c:499:  dev_set_drvdata(dev, NULL);
> drivers/base/dd.c:902:          dev_set_drvdata(dev, NULL);
>
> Last one is the point of your interest.
>