Patch for stable 4.5+ (dma-buf: add support for compat ioctl)

Patch for stable 4.5+ (dma-buf: add support for compat ioctl)

[Sumit Semwal]

Hello,

Upstream commit 888022c0473d079bff9b47fb50434b1f20f8f37f
Subject: dma-buf: add support for compat ioctl
Applicable to: 4.5+ stable kernels

The cc:stable got missed while this patch got applied for mainline; it
allows a 32-bit application to use DMA_BUF_IOCTL_SYNC with 64-bit
kernel.

Best regards,
Sumit.

Re: Patch for stable 4.5+ (dma-buf: add support for compat ioctl)

[Greg KH]

On Fri, Apr 14, 2017 at 11:23:20AM +0530, Sumit Semwal wrote:
> Hello,
> 
> Upstream commit 888022c0473d079bff9b47fb50434b1f20f8f37f
> Subject: dma-buf: add support for compat ioctl
> Applicable to: 4.5+ stable kernels
> 
> The cc:stable got missed while this patch got applied for mainline; it
> allows a 32-bit application to use DMA_BUF_IOCTL_SYNC with 64-bit
> kernel.

Is this a new feature being added?  Why is this a stable kernel patch?

And always cc: the authors of the patch involved when asking for a
stable backport, it keeps me from having to add them to the cc: when
asking questions like this :)

thanks,

greg k-h

Re: Patch for stable 4.5+ (dma-buf: add support for compat ioctl)

[Sumit Semwal]

Hi Greg,

On 14 April 2017 at 14:49, Greg KH <greg@kroah.com> wrote:
> On Fri, Apr 14, 2017 at 11:23:20AM +0530, Sumit Semwal wrote:
>> Hello,
>>
>> Upstream commit 888022c0473d079bff9b47fb50434b1f20f8f37f
>> Subject: dma-buf: add support for compat ioctl
>> Applicable to: 4.5+ stable kernels
>>
>> The cc:stable got missed while this patch got applied for mainline; it
>> allows a 32-bit application to use DMA_BUF_IOCTL_SYNC with 64-bit
>> kernel.
>
> Is this a new feature being added?  Why is this a stable kernel patch?
>
So commit
c11e391da2a8fe973c3c2398452000bed505851e: ("dma-buf: Add ioctls to
allow userspace to flush") added ioctls to dma-buf in 4.5 kernel to
support DMA_BUF_IOCTL_SYNC, but we missed adding the compat_ioctl
support at the time. This obviously meant that we weren't able to use
this IOCTL from a 32-bit application with a 64-bit kernel.

This patch adds the missing compat_ioctl support for dma-buf.

> And always cc: the authors of the patch involved when asking for a
> stable backport, it keeps me from having to add them to the cc: when
> asking questions like this :)
>
Clearly, I'm a newbie to the whole stable process :) - I will keep
this in mind as well!

> thanks,
>
> greg k-h

Best regards,
Sumit.

Re: Patch for stable 4.5+ (dma-buf: add support for compat ioctl)

[Marek Szyprowski]

Hi Greg,

On 2017-04-14 11:19, Greg KH wrote:
> On Fri, Apr 14, 2017 at 11:23:20AM +0530, Sumit Semwal wrote:
>> Upstream commit 888022c0473d079bff9b47fb50434b1f20f8f37f
>> Subject: dma-buf: add support for compat ioctl
>> Applicable to: 4.5+ stable kernels
>>
>> The cc:stable got missed while this patch got applied for mainline; it
>> allows a 32-bit application to use DMA_BUF_IOCTL_SYNC with 64-bit
>> kernel.
> Is this a new feature being added?  Why is this a stable kernel patch?

I don't thing this is a feature. This patch is definitely a bugfix - 
without it
the same application on 64bit kernel fails if compiled in 32bit mode and 
works
if compiled as 64bit.

I should have added a following tag:
Fixes: c11e391da2a8 ("dma-buf: Add ioctls to allow userspace to flush")

> And always cc: the authors of the patch involved when asking for a
> stable backport, it keeps me from having to add them to the cc: when
> asking questions like this :)

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

Re: Patch for stable 4.5+ (dma-buf: add support for compat ioctl)

[Greg KH]

On Fri, Apr 14, 2017 at 11:23:20AM +0530, Sumit Semwal wrote:
> Hello,
> 
> Upstream commit 888022c0473d079bff9b47fb50434b1f20f8f37f
> Subject: dma-buf: add support for compat ioctl
> Applicable to: 4.5+ stable kernels
> 
> The cc:stable got missed while this patch got applied for mainline; it
> allows a 32-bit application to use DMA_BUF_IOCTL_SYNC with 64-bit
> kernel.

Now queued up, thanks.

greg k-h