linux-kernel - Re: [PATCH] media: imx7-mipi-csis: Add the missed v4l2_async_notifier_cleanup in remove

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Message-ID: <def58acb-ae42-856a-f61d-645dcfbbe3f7@gmail.com>
Date:   Thu, 12 Dec 2019 18:05:11 -0800
From:   Steve Longerbeam <slongerbeam@...il.com>
To:     Rui Miguel Silva <rmfrfs@...il.com>,
        Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Chuhong Yuan <hslester96@...il.com>, devel@...verdev.osuosl.org,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        linux-kernel@...r.kernel.org, NXP Linux Team <linux-imx@....com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org
Subject: Re: [PATCH] media: imx7-mipi-csis: Add the missed
 v4l2_async_notifier_cleanup in remove

On 12/12/19 11:08 AM, Rui Miguel Silva wrote:
> Hi Dan,
> Thanks for the inputs.
> On Thu, Dec 12, 2019 at 02:51:34PM +0300, Dan Carpenter wrote:
>> On Mon, Dec 09, 2019 at 04:58:28PM +0800, Chuhong Yuan wrote:
>>> All drivers in imx call v4l2_async_notifier_cleanup() after
>>> unregistering the notifier except this driver.  This should be a
>>> miss and we need to add the call to fix it.
>>>
>>> Signed-off-by: Chuhong Yuan <hslester96@...il.com> ---
>>> drivers/staging/media/imx/imx7-mipi-csis.c | 1 +
>>>   1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/staging/media/imx/imx7-mipi-csis.c
>>> b/drivers/staging/media/imx/imx7-mipi-csis.c index
>>> 99166afca071..2bfa85bb84e7 100644 ---
>>> a/drivers/staging/media/imx/imx7-mipi-csis.c +++
>>> b/drivers/staging/media/imx/imx7-mipi-csis.c @@ -1105,6 +1105,7 @@
>>> static int mipi_csis_remove(struct platform_device *pdev)
>>> mipi_csis_debugfs_exit(state);
>>> v4l2_async_unregister_subdev(&state->mipi_sd);
>>> v4l2_async_notifier_unregister(&state->subdev_notifier); +
>>> v4l2_async_notifier_cleanup(&state->subdev_notifier);
>>>   
>> In this case the "state->subdev_notifier" was never initialized or
>> used so both v4l2_async_notifier_unregister() and
>> v4l2_async_notifier_cleanup() are no-ops.
> I have applied this patch on top of Steve's series [0], since by the
> timeline I was expecting to be applied before this one, that series
> adds a bound notifier, even though, it is not named the same, eheh.
>
> That trigged me to think that this cleanup was correct since a
> notifier was initialized in probe.
>
> But as you say, it is a no-ops in the end.
>
> @Steve, that said, it looks that in [0], you will need to add some
> unregister and cleanup for the notifiers that you are adding in
> several places.

Well, turns out I had failed to notice that an async notifier was 
already included in 'struct imx7_csi' as 'subdev_notifier', even though 
it was unused. So I ended up creating a duplicate 'notifier'. I'll 
cleaning that up in v3 of [0].

Steve

> A patch to fix this will follow.
>
> ------
> Cheers,
>       Rui
>
>
>
> [0]: https://patchwork.kernel.org/project/linux-media/list/?series=207517
>
>> We should just delete "subdev_notifier".
>>
>> regards, dan carpenter
>>
>> _______________________________________________ devel mailing list
>> devel@...uxdriverproject.org
>> http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel

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