[alsa-devel] [BACKPORT 4.4.y 02/25] ALSA: compress: add support for 32bit calls in a 64bit kernel

[Arnd Bergmann]

On Tue, Mar 26, 2019 at 2:23 AM Greg KH <gregkh at linuxfoundation.org> wrote:
>
> On Fri, Mar 22, 2019 at 04:43:53PM +0100, Arnd Bergmann wrote:
> > From: Ravindra Lokhande <rlokhande at nvidia.com>
> >
> > Compress offload does not support ioctl calls from a 32bit userspace
> > in a 64 bit kernel. This patch adds support for ioctls from a 32bit
> > userspace in a 64bit kernel
> >
> > Signed-off-by: Ravindra Lokhande <rlokhande at nvidia.com>
> > Acked-by: Vinod Koul <vinod.koul at intel.com>
> > Signed-off-by: Takashi Iwai <tiwai at suse.de>
> > (cherry picked from commit c10368897e104c008c610915a218f0fe5fa4ec96)
> > Signed-off-by: Arnd Bergmann <arnd at arndb.de>
> > ---
> >  sound/core/compress_offload.c | 13 +++++++++++++
> >  1 file changed, 13 insertions(+)
>
> How is this not a "new feature"?  What bug does this fix?  Has this ever
> worked in the past?

It has never worked in the past, but I consider it a bug for the compat layer
to behave differently from native code. In this case, any 32-bit application
using the SNDRV_COMPRESS_* ioctls will just fail to do anything on
a 64-bit kernel at all without the trivial fix that should have been there when
the driver was originally merged.

     Arnd