Re: [RESEND PATCH v4 1/4] dma-mapping: benchmark: Add padding to ensure uABI remained consistent

[Jonathan Cameron]

On Sat, 14 Jun 2025 22:34:51 +0800
Qinxin Xia <xiaqinxin@xxxxxxxxxx> wrote:

> The padding field in the structure was previously reserved to
> maintain a stable interface for potential new fields, ensuring
> compatibility with user-space shared data structures.
> However,it was accidentally removed by tiantao in a prior commit,
> which may lead to incompatibility between user space and the kernel.
> 
> This patch reinstates the padding to restore the original structure
> layout and preserve compatibility.
> 
> Fixes: 8ddde07a3d28 ("dma-mapping: benchmark: extract a common header file for map_benchmark definition")
> Cc: stable@xxxxxxxxxxxxxxx
> Acked-by: Barry Song <baohua@xxxxxxxxxx>
> Signed-off-by: Qinxin Xia <xiaqinxin@xxxxxxxxxx>

FWIW I checked the patch above indeed accidentally dropped the padding and the structure
is copied to userspace so this fix is correct.  Given it's not in a uapi header this
only really affects the selftest I think this is mostly a case of there possibly being
out of tree tools with a local copy of this structure definition.

Reviewed-by: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>