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Subject: Re: [PATCH] dma-buf: add support for compat ioctl
To: Marek Szyprowski <m.szyprowski@samsung.com>,
        linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org
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Cc: linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
From: =?UTF-8?Q?Christian_K=c3=b6nig?= <deathsimple@vodafone.de>
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Date: Tue, 21 Feb 2017 16:08:25 +0100
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Am 21.02.2017 um 15:55 schrieb Marek Szyprowski:
> Dear All,
>
> On 2017-02-21 15:37, Marek Szyprowski wrote:
>> Hi Christian,
>>
>> On 2017-02-21 14:59, Christian König wrote:
>>> Am 21.02.2017 um 14:21 schrieb Marek Szyprowski:
>>>> Add compat ioctl support to dma-buf. This lets one to use 
>>>> DMA_BUF_IOCTL_SYNC
>>>> ioctl from 32bit application on 64bit kernel. Data structures for 
>>>> both 32
>>>> and 64bit modes are same, so there is no need for additional 
>>>> translation
>>>> layer.
>>>
>>> Well I might be wrong, but IIRC compat_ioctl was just optional and 
>>> if not specified unlocked_ioctl was called instead.
>>>
>>> If that is true your patch wouldn't have any effect at all.
>>
>> Well, then why I got -ENOTTY in the 32bit test app for this ioctl on 
>> 64bit ARM64 kernel without this patch?
>>
>
> I've checked in fs/compat_ioctl.c, I see no fallback in 
> COMPAT_SYSCALL_DEFINE3,
> so one has to provide compat_ioctl callback to have ioctl working with 
> 32bit
> apps.

Then my memory cheated on me.

In this case the patch is Reviewed-by: Christian König 
<christian.koenig@amd.com>.

Regards,
Christian.

>
> Best regards