Hi,
On Fri, Feb 03, 2023 at 05:22:40PM +0100, Takashi Iwai wrote:
On Thu, 02 Feb 2023 14:37:08 +0100, Takashi Sakamoto wrote:
Current structure includes no field to express the number of messages copied to user space, thus user space application needs to information out of the structure to parse the content of structure.
This commit adds a field to express the number of messages copied to user space since It is more preferable to use self-contained structure.
Kees Cook proposed an idea of annotation for bound of flexible arrays in his future improvement for flexible-length array in kernel. The additional field for message count is suitable to the idea as well.
Reference: https://people.kernel.org/kees/bounded-flexible-arrays-in-c Signed-off-by: Takashi Sakamoto o-takashi@sakamocchi.jp
Wouldn't changing this break the existing application that talks with the older ABI? Just to be sure...
You may well have the concern, indeed.
The structure is not exposed to user space yet, since it was added by a commit ab811cfffa9 ("ALSA: fireface: update UAPI for data of knob control"). It just exists in your (and mine) tree at present.
Thanks
Takashi Sakamoto