linux-kernel - Re: [PATCH 1/3] media: ngene: Replace semaphore cmd

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Date:   Tue, 13 Jun 2017 14:28:47 +0530
From:   Binoy Jayan <binoy.jayan@...aro.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Rajendra <rnayak@...eaurora.org>,
        Mark Brown <broonie@...nel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Julia Lawall <Julia.Lawall@...6.fr>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Cao jin <caoj.fnst@...fujitsu.com>,
        Linux Media Mailing List <linux-media@...r.kernel.org>
Subject: Re: [PATCH 1/3] media: ngene: Replace semaphore cmd_mutex with mutex

Hi Arnd,

On 9 June 2017 at 16:06, Arnd Bergmann <arnd@...db.de> wrote:

>> Thank you for pointing out that. I'll check the
>> concurrency part. By the way why do we need mutex_destoy?
>> To debug an aberrate condition?
>
> At first I suspected the down() here was added for the same
> purpose as a mutex_destroy: to ensure that we are in a sane
> state before we free the device structure, but the way they
> achieve that is completely different.
>
> However, if there is any way that a command may still be in
> progress by the time we get to ngene_stop(), we may also
> be lacking reference counting on the ngene structure here.
> So far I haven't found any of those, and think the mutex_destroy()
> is sufficient here as a debugging help.

I've made the necessary changes. Thank you for reviewing all the patches.

Regards,
Binoy