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

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Message-ID: <ed555287-1f31-4831-a11c-799e177a8f2f@igalia.com>
Date: Mon, 13 Oct 2025 23:43:28 +0900
From: Changwoo Min <changwoo@...lia.com>
To: Lukasz Luba <lukasz.luba@....com>
Cc: christian.loehle@....com, tj@...nel.org, pavel@...nel.org,
 len.brown@...el.com, rafael@...nel.org, kernel-dev@...lia.com,
 linux-pm@...r.kernel.org, sched-ext@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND v4 05/10] PM: EM: Add a skeleton code for netlink
 notification



On 10/13/25 22:53, Lukasz Luba wrote:
> 
> 
> On 10/13/25 14:46, Changwoo Min wrote:
>>
>>
>> On 10/7/25 00:44, Lukasz Luba wrote:
>>>
>>>
>>> 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@...lia.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@....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@...lia.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@...lia.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.
>>
>>   That makes sense to me.
>>
>>>
>>> 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.
>>>
>>
>> Sure, after moving 3/10 after this, I will move the changes made in 3/10
>> to em_netlink.h. I will keep the implementation of
>> for_each_em_perf_domain() and em_perf_domain_get_by_id() in
>> energy_model.c since it it not ideal to expose em_pd_list_mutex, etc.
>> outside of energy_mode.c. And, this requires to include "em_netlink.h"
>> from energy_model.c.
>>
> 
> Sounds good. These are only minor changes because it has nice shape
> already.
> 
> I was able to test it last weekend and it works on my setup now.
> I can see the messages coming in the user-space, so it should
> work as designed.
> 
> Thank you Changwoo! Looking forward for your v5.

Thank you Lukasz for testing. I will send v5 soon after final testing.

Regards,
Changwoo Min