linux-kernel - Re: [PATCH v3 6/8] media: atomisp: remove compat

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Date:   Mon, 14 Jun 2021 20:07:59 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        "Lad, Prabhakar" <prabhakar.csengg@...il.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Vaibhav Gupta <vaibhavgupta40@...il.com>,
        Liu Shixin <liushixin2@...wei.com>,
        Jacopo Mondi <jacopo+renesas@...ndi.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linux-staging@...ts.linux.dev, Hans Verkuil <hverkuil@...all.nl>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH v3 6/8] media: atomisp: remove compat_ioctl32 code

Hi Arnd,

Thank you for the patch.

On Mon, Jun 14, 2021 at 12:34:07PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> This is one of the last remaining users of compat_alloc_user_space()
> and copy_in_user(), which are in the process of getting removed.
> 
> As of commit 57e6b6f2303e ("media: atomisp_fops.c: disable
> atomisp_compat_ioctl32"), nothing in this file is actually getting used
> as the only reference has been stubbed out.
> 
> Remove the entire file -- anyone willing to restore the functionality
> can equally well just look up the contents in the git history if needed.
> 
> Cc: Sakari Ailus <sakari.ailus@...ux.intel.com>
> Cc: Hans Verkuil <hverkuil@...all.nl>
> Acked-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
> Suggested-by: Christoph Hellwig <hch@....de>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Acked-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> ---
>  drivers/staging/media/atomisp/Makefile        |    1 -
>  drivers/staging/media/atomisp/TODO            |    5 +
>  .../atomisp/pci/atomisp_compat_ioctl32.c      | 1202 -----------------
>  .../staging/media/atomisp/pci/atomisp_fops.c  |    8 +-
>  4 files changed, 8 insertions(+), 1208 deletions(-)
>  delete mode 100644 drivers/staging/media/atomisp/pci/atomisp_compat_ioctl32.c
> 
> diff --git a/drivers/staging/media/atomisp/Makefile b/drivers/staging/media/atomisp/Makefile
> index 51498b2e85b8..606b7754fdfd 100644
> --- a/drivers/staging/media/atomisp/Makefile
> +++ b/drivers/staging/media/atomisp/Makefile
> @@ -16,7 +16,6 @@ atomisp-objs += \
>  	pci/atomisp_acc.o \
>  	pci/atomisp_cmd.o \
>  	pci/atomisp_compat_css20.o \
> -	pci/atomisp_compat_ioctl32.o \
>  	pci/atomisp_csi2.o \
>  	pci/atomisp_drvfs.o \
>  	pci/atomisp_file.o \
> diff --git a/drivers/staging/media/atomisp/TODO b/drivers/staging/media/atomisp/TODO
> index 6987bb2d32cf..2d1ef9eb262a 100644
> --- a/drivers/staging/media/atomisp/TODO
> +++ b/drivers/staging/media/atomisp/TODO
> @@ -120,6 +120,11 @@ TODO
>      for this driver until the other work is done, as there will be a lot
>      of code churn until this driver becomes functional again.
>  
> +16. Fix private ioctls to not need a compat_ioctl handler for running
> +    32-bit tasks. The compat code has been removed because of bugs,
> +    and should not be needed for modern drivers. Fixing this properly
> +    unfortunately means an incompatible ABI change.
> +
>  Limitations
>  ===========
>  

[snip]

> diff --git a/drivers/staging/media/atomisp/pci/atomisp_fops.c b/drivers/staging/media/atomisp/pci/atomisp_fops.c
> index 26d05474a035..be58f21ab208 100644
> --- a/drivers/staging/media/atomisp/pci/atomisp_fops.c
> +++ b/drivers/staging/media/atomisp/pci/atomisp_fops.c
> @@ -1283,7 +1283,8 @@ const struct v4l2_file_operations atomisp_fops = {
>  	.unlocked_ioctl = video_ioctl2,
>  #ifdef CONFIG_COMPAT
>  	/*
> -	 * There are problems with this code. Disable this for now.
> +	 * this was removed because of bugs, the interface
> +	 * needs to be made safe for compat tasks instead.
>  	.compat_ioctl32 = atomisp_compat_ioctl32,
>  	 */
>  #endif
> @@ -1297,10 +1298,7 @@ const struct v4l2_file_operations atomisp_file_fops = {
>  	.mmap = atomisp_file_mmap,
>  	.unlocked_ioctl = video_ioctl2,
>  #ifdef CONFIG_COMPAT
> -	/*
> -	 * There are problems with this code. Disable this for now.
> -	.compat_ioctl32 = atomisp_compat_ioctl32,
> -	 */
> +	/* .compat_ioctl32 = atomisp_compat_ioctl32, */
>  #endif
>  	.poll = atomisp_poll,
>  };

-- 
Regards,

Laurent Pinchart