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@igalia.com>
---
 kernel/power/em_netlink.c | 56 +++++++++++++++++++++++++++++++++++++++
 kernel/power/em_netlink.h | 18 +++++++++++++
 2 files changed, 74 insertions(+)

diff --git a/kernel/power/em_netlink.c b/kernel/power/em_netlink.c
index 59953cfedf78..ff6aa848d998 100644
--- a/kernel/power/em_netlink.c
+++ b/kernel/power/em_netlink.c
@@ -213,6 +213,62 @@ int em_nl_get_pd_table_doit(struct sk_buff *skb, struct genl_info *info)
 	return ret;
 }
 
+
+/**************************** Event encoding *********************************/
+int em_notify_pd_created(const struct em_perf_domain *pd)
+{
+	return -EOPNOTSUPP;
+}
+
+int em_notify_pd_updated(const struct em_perf_domain *pd)
+{
+	return -EOPNOTSUPP;
+}
+
+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));
+}
+
+int 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 0;
+
+	msg_sz = __em_notify_pd_deleted_size(pd);
+
+	msg = genlmsg_new(msg_sz, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	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 0;
+
+out_free_msg:
+	nlmsg_free(msg);
+	return ret;
+}
+
+/**************************** 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 acd186c92d6b..938c84ca1f40 100644
--- a/kernel/power/em_netlink.h
+++ b/kernel/power/em_netlink.h
@@ -10,7 +10,25 @@
 #define _EM_NETLINK_H
 
 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_NET)
+int em_notify_pd_created(const struct em_perf_domain *pd);
+int em_notify_pd_deleted(const struct em_perf_domain *pd);
+int em_notify_pd_updated(const struct em_perf_domain *pd);
+
 #else
+static inline int em_notify_pd_created(const struct em_perf_domain *pd)
+{
+	return 0;
+}
+
+static inline int em_notify_pd_deleted(const struct em_perf_domain *pd)
+{
+	return 0;
+}
+
+static inline int em_notify_pd_updated(const struct em_perf_domain *pd)
+{
+	return 0;
+}
 #endif
 
 #endif /* _EM_NETLINK_H */
-- 
2.51.0

On 9/21/25 04:19, 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@igalia.com>
> ---
>   kernel/power/em_netlink.c | 56 +++++++++++++++++++++++++++++++++++++++
>   kernel/power/em_netlink.h | 18 +++++++++++++
>   2 files changed, 74 insertions(+)
> 
> diff --git a/kernel/power/em_netlink.c b/kernel/power/em_netlink.c
> index 59953cfedf78..ff6aa848d998 100644
> --- a/kernel/power/em_netlink.c
> +++ b/kernel/power/em_netlink.c
> @@ -213,6 +213,62 @@ int em_nl_get_pd_table_doit(struct sk_buff *skb, struct genl_info *info)
>   	return ret;
>   }
>   
> +
> +/**************************** Event encoding *********************************/
> +int em_notify_pd_created(const struct em_perf_domain *pd)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +int em_notify_pd_updated(const struct em_perf_domain *pd)
> +{
> +	return -EOPNOTSUPP;
> +}

Those two functions doesn't belong to this patch $subject.
I would recommend adding them in the following patch where they
are properly defined.

> +
> +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));
> +}
> +
> +int 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 0;
> +
> +	msg_sz = __em_notify_pd_deleted_size(pd);
> +
> +	msg = genlmsg_new(msg_sz, GFP_KERNEL);
> +	if (!msg)
> +		return -ENOMEM;
> +
> +	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 0;
> +
> +out_free_msg:
> +	nlmsg_free(msg);
> +	return ret;
> +}

It looks like we don't handle the error outputs of those
em_notify_* function (based on last patch in the set.

Can we just simply change the function to void?
It would also avoid some spurious static analysis tools checking the
code in future.