On Wed, 2020-09-30 at 17:05 -0700, Jakub Kicinski wrote:
> There are holes and oversized members in struct genl_family.
>
> Before: /* size: 104, cachelines: 2, members: 16 */
> After: /* size: 88, cachelines: 2, members: 16 */
>
> The command field in struct genlmsghdr is a u8, so no point
> in the operation count being 32 bit. Also operation 0 is
> usually undefined, so we only need 255 entries.
>
> netnsok and parallel_ops are only ever initialized to true.
The fundamentally are bools, so that makes sense :)
> We can grow the fields as needed, compiler should warn us
> if someone tries to assign larger constants.
>
> Signed-off-by: Jakub Kicinski <k...@kernel.org>
> ---
> include/net/genetlink.h | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/include/net/genetlink.h b/include/net/genetlink.h
> index a3484fd736d6..0033c76ff094 100644
> --- a/include/net/genetlink.h
> +++ b/include/net/genetlink.h
> @@ -48,8 +48,11 @@ struct genl_family {
> char name[GENL_NAMSIZ];
> unsigned int version;
> unsigned int maxattr;
> - bool netnsok;
> - bool parallel_ops;
> + unsigned int mcgrp_offset; /* private */
In practice, we can probably also shrink that to u16, since it just
gives you the offset of the multicast groups this family has in the
whole table - and we'll hopefully never run more than 2**16 multicast
groups across all genetlink families :)
But it also doesn't matter much.
Reviewed-by: Johannes Berg <johan...@sipsolutions.net>
johannes
