Re: [PATCH RESEND v4 05/10] PM: EM: Add a skeleton code for netlink notification

[Lukasz Luba <lukasz.luba@arm.com>]

On 9/21/25 04:19, Changwoo Min wrote:
> Add a boilerplate code for netlink notification to register the new
> protocol family. Also, initialize and register the netlink during booting.
> The initialization is called at the postcore level, which is late enough
> after the generic netlink is initialized.
> 
> Finally, update MAINTAINERS to include new files.
> 
> Signed-off-by: Changwoo Min <changwoo@igalia.com>
> ---
>   MAINTAINERS               |  2 +-
>   kernel/power/Makefile     |  5 ++++-
>   kernel/power/em_netlink.c | 35 +++++++++++++++++++++++++++++++++++
>   kernel/power/em_netlink.h | 16 ++++++++++++++++
>   4 files changed, 56 insertions(+), 2 deletions(-)
>   create mode 100644 kernel/power/em_netlink.c
>   create mode 100644 kernel/power/em_netlink.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 0992029d271d..ba528836eac1 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9034,7 +9034,7 @@ F:	include/linux/energy_model.h
>   F:	Documentation/power/energy-model.rst
>   F:	Documentation/netlink/specs/em.yaml
>   F:	include/uapi/linux/energy_model.h
> -F:	kernel/power/em_netlink_autogen.*
> +F:	kernel/power/em_netlink*.*
>   
>   EPAPR HYPERVISOR BYTE CHANNEL DEVICE DRIVER
>   M:	Laurentiu Tudor <laurentiu.tudor@nxp.com>
> diff --git a/kernel/power/Makefile b/kernel/power/Makefile
> index 874ad834dc8d..284a760aade7 100644
> --- a/kernel/power/Makefile
> +++ b/kernel/power/Makefile
> @@ -21,4 +21,7 @@ obj-$(CONFIG_PM_WAKELOCKS)	+= wakelock.o
>   
>   obj-$(CONFIG_MAGIC_SYSRQ)	+= poweroff.o
>   
> -obj-$(CONFIG_ENERGY_MODEL)	+= energy_model.o
> +obj-$(CONFIG_ENERGY_MODEL)	+= em.o
> +em-y				:= energy_model.o
> +em-$(CONFIG_NET)		+= em_netlink_autogen.o em_netlink.o
> +
> diff --git a/kernel/power/em_netlink.c b/kernel/power/em_netlink.c
> new file mode 100644
> index 000000000000..f3fbfeff29a4
> --- /dev/null
> +++ b/kernel/power/em_netlink.c
> @@ -0,0 +1,35 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + *
> + * Generic netlink for energy model.
> + *
> + * Copyright (c) 2025 Valve Corporation.
> + * Author: Changwoo Min <changwoo@igalia.com>
> + */
> +
> +#define pr_fmt(fmt) "energy_model: " fmt
> +
> +#include <linux/energy_model.h>
> +#include <net/sock.h>
> +#include <net/genetlink.h>
> +#include <uapi/linux/energy_model.h>
> +
> +#include "em_netlink.h"
> +#include "em_netlink_autogen.h"
> +
> +int em_nl_get_pds_doit(struct sk_buff *skb, struct genl_info *info)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +int em_nl_get_pd_table_doit(struct sk_buff *skb, struct genl_info *info)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static int __init em_netlink_init(void)
> +{
> +	return genl_register_family(&em_nl_family);
> +}
> +postcore_initcall(em_netlink_init);
> +
> diff --git a/kernel/power/em_netlink.h b/kernel/power/em_netlink.h
> new file mode 100644
> index 000000000000..acd186c92d6b
> --- /dev/null
> +++ b/kernel/power/em_netlink.h
> @@ -0,0 +1,16 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + *
> + * Generic netlink for energy model.
> + *
> + * Copyright (c) 2025 Valve Corporation.
> + * Author: Changwoo Min <changwoo@igalia.com>
> + */
> +#ifndef _EM_NETLINK_H
> +#define _EM_NETLINK_H
> +
> +#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_NET)
> +#else
> +#endif
> +
> +#endif /* _EM_NETLINK_H */

Actually, those declarations of functions from patch 3/10 can
live in this header. We would avoid creating more local headers
in such case.

Then the patch 3/10 would have to go after this patch when
this header is introduced.

Please ignore the comment in the patch 3/10 and try to
use this header. It is also logically linked to the
notifications, so belongs to such header IMHO.