linux-kernel - Re: [PATCH] ion_test: Add compat

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Date:	Thu, 19 Dec 2013 14:52:38 -0800
From:	Colin Cross <ccross@...roid.com>
To:	John Stultz <john.stultz@...aro.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Greg KH <gregkh@...uxfoundation.org>,
	Android Kernel Team <kernel-team@...roid.com>
Subject: Re: [PATCH] ion_test: Add compat_ioctl support

On Thu, Dec 19, 2013 at 2:40 PM, John Stultz <john.stultz@...aro.org> wrote:
> Prior to subitting this, Colin reworked the compat_ioctl support
> for the ion_test driver, moving the structure to be the same size
> on both 32 and 64 bit architectures.
>
> Two small things were left out. The compat_ioctl ptr assignment,
> and the fact that despite having uniform sized types in the
> structure, the structure pads out to different sizes on different
> arches.
>
> This patch resolves this issue by setting the write flag as
> a __u64, and adding the compat_ioctl ptr.
>
> While this does affect the ABI for 32bit users, its only
> the ABI for the ion_test driver, not ion itself.
>
> Cc: Colin Cross <ccross@...roid.com>
> Cc: Greg KH <gregkh@...uxfoundation.org>
> Cc: Android Kernel Team <kernel-team@...roid.com>
> Signed-off-by: John Stultz <john.stultz@...aro.org>
> ---
>  drivers/staging/android/ion/ion_test.c  | 1 +
>  drivers/staging/android/uapi/ion_test.h | 2 +-
>  2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/staging/android/ion/ion_test.c b/drivers/staging/android/ion/ion_test.c
> index 3e20349..654acb5 100644
> --- a/drivers/staging/android/ion/ion_test.c
> +++ b/drivers/staging/android/ion/ion_test.c
> @@ -231,6 +231,7 @@ static int ion_test_release(struct inode *inode, struct file *file)
>  static const struct file_operations ion_test_fops = {
>         .owner = THIS_MODULE,
>         .unlocked_ioctl = ion_test_ioctl,
> +       .compat_ioctl = ion_test_ioctl,

Setting the compat_ioctl to the same thing as unlocked_ioctl shouldn't
be necessary, compat_sys_ioctl will fall through to do_vfs_ioctl if
compat_ioctl is not set, which will call unlocked_ioctl.

>         .open = ion_test_open,
>         .release = ion_test_release,
>  };
> diff --git a/drivers/staging/android/uapi/ion_test.h b/drivers/staging/android/uapi/ion_test.h
> index 614d1e3..f1727f5 100644
> --- a/drivers/staging/android/uapi/ion_test.h
> +++ b/drivers/staging/android/uapi/ion_test.h
> @@ -31,7 +31,7 @@ struct ion_test_rw_data {
>         __u64 ptr;
>         __u64 offset;
>         __u64 size;
> -       int write;
> +       __u64 write;
>  };

Whoops, missed that one.  Can you add "int padding" after "int write"
instead?  That at least lets us use the 32 bits later.
--
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