linux-kernel - Re: [PATCH v5 08/10] PM: EM: Implement em_notify_pd

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Message-ID: <fd486f5e-784f-43f1-83a4-44ea43019921@arm.com>
Date: Tue, 14 Oct 2025 09:47:02 +0100
From: Lukasz Luba <lukasz.luba@....com>
To: Changwoo Min <changwoo@...lia.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 v5 08/10] PM: EM: Implement em_notify_pd_deleted()



On 10/14/25 01:10, Changwoo Min wrote:
> Add the event notification infrastructure and implement the event
> notification for when a performance domain is deleted (EM_CMD_PD_DELETED).
> 
> The event contains the ID of the performance domain (EM_A_PD_TABLE_PD_ID)
> so the userspace can identify the changed performance domain for further
> processing.
> 
> Signed-off-by: Changwoo Min <changwoo@...lia.com>
> ---
>   kernel/power/em_netlink.c | 46 +++++++++++++++++++++++++++++++++++++++
>   kernel/power/em_netlink.h |  3 +++
>   2 files changed, 49 insertions(+)
> 
> diff --git a/kernel/power/em_netlink.c b/kernel/power/em_netlink.c
> index 2addc143401b..90ae6f1c9c9a 100644
> --- a/kernel/power/em_netlink.c
> +++ b/kernel/power/em_netlink.c
> @@ -213,6 +213,52 @@ int em_nl_get_pd_table_doit(struct sk_buff *skb, struct genl_info *info)
>   	return ret;
>   }
>   
> +
> +/**************************** Event encoding *********************************/
> +static int __em_notify_pd_deleted_size(const struct em_perf_domain *pd)
> +{
> +	int id_sz = nla_total_size(sizeof(u32)); /* EM_A_PD_TABLE_PD_ID */
> +
> +	return nlmsg_total_size(genlmsg_msg_size(id_sz));
> +}
> +
> +void em_notify_pd_deleted(const struct em_perf_domain *pd)
> +{
> +	struct sk_buff *msg;
> +	int ret = -EMSGSIZE;
> +	void *hdr;
> +	int msg_sz;
> +
> +	if (!genl_has_listeners(&em_nl_family, &init_net, EM_NLGRP_EVENT))
> +		return;
> +
> +	msg_sz = __em_notify_pd_deleted_size(pd);
> +
> +	msg = genlmsg_new(msg_sz, GFP_KERNEL);
> +	if (!msg)
> +		return;
> +
> +	hdr = genlmsg_put(msg, 0, 0, &em_nl_family, 0, EM_CMD_PD_DELETED);
> +	if (!hdr)
> +		goto out_free_msg;
> +
> +	if (nla_put_u32(msg, EM_A_PD_TABLE_PD_ID, pd->id)) {
> +		ret = -EMSGSIZE;
> +		goto out_free_msg;
> +	}
> +
> +	genlmsg_end(msg, hdr);
> +
> +	genlmsg_multicast(&em_nl_family, msg, 0, EM_NLGRP_EVENT, GFP_KERNEL);
> +
> +	return;
> +
> +out_free_msg:
> +	nlmsg_free(msg);
> +	return;
> +}
> +
> +/**************************** Initialization *********************************/
>   static int __init em_netlink_init(void)
>   {
>   	return genl_register_family(&em_nl_family);
> diff --git a/kernel/power/em_netlink.h b/kernel/power/em_netlink.h
> index 8114b018c73b..d56e5865e1ed 100644
> --- a/kernel/power/em_netlink.h
> +++ b/kernel/power/em_netlink.h
> @@ -13,6 +13,7 @@
>   int for_each_em_perf_domain(int (*cb)(struct em_perf_domain*, void *),
>   			    void *data);
>   struct em_perf_domain *em_perf_domain_get_by_id(int id);
> +void em_notify_pd_deleted(const struct em_perf_domain *pd);
>   #else
>   static inline
>   int for_each_em_perf_domain(int (*cb)(struct em_perf_domain*, void *),
> @@ -25,6 +26,8 @@ struct em_perf_domain *em_perf_domain_get_by_id(int id)
>   {
>   	return NULL;
>   }
> +
> +static inline void em_notify_pd_deleted(const struct em_perf_domain *pd) {}
>   #endif
>   
>   #endif /* _EM_NETLINK_H */


LGTM,

Reviewed-by: Lukasz Luba <lukasz.luba@....com>