On 9/21/25 04:19, Changwoo Min wrote:
> Add an iterator function (for_each_em_perf_domain) that iterates all the
> performance domains in the global list. A passed callback function (cb) is
> called for each performance domain.
>
> Additionally, add a lookup function (em_perf_domain_get_by_id) that
> searches for a performance domain by matching the ID in the global list.
>
> Signed-off-by: Changwoo Min <changwoo@igalia.com>
> ---
> include/linux/energy_model.h | 15 +++++++++++++++
> kernel/power/energy_model.c | 34 ++++++++++++++++++++++++++++++++++
> 2 files changed, 49 insertions(+)
>
> diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
> index 43aa6153dc57..21279e779188 100644
> --- a/include/linux/energy_model.h
> +++ b/include/linux/energy_model.h
> @@ -344,6 +344,10 @@ struct em_perf_state *em_perf_state_from_pd(struct em_perf_domain *pd)
> return rcu_dereference(pd->em_table)->state;
> }
>
> +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);
> +
This doesn't have to go into this header.
> #else
> struct em_data_callback {};
> #define EM_ADV_DATA_CB(_active_power_cb, _cost_cb) { }
> @@ -420,6 +424,17 @@ int em_update_performance_limits(struct em_perf_domain *pd,
> }
> static inline void em_adjust_cpu_capacity(unsigned int cpu) {}
> static inline void em_rebuild_sched_domains(void) {}
> +static inline
> +int for_each_em_perf_domain(int (*cb)(struct em_perf_domain*, void *),
> + void *data)
> +{
> + return -EINVAL;
> +}
> +static inline
> +struct em_perf_domain *em_perf_domain_get_by_id(int id)
> +{
> + return NULL;
> +}
> #endif
Please create a local helpers header:
kernel/power/em_helpers.h
and add these two declarations there. In that new
local header there is no need to implement the empty
inline functions as well (so would be simpler).
>
> #endif
> diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
> index 8998a7f4910a..740076d24479 100644
> --- a/kernel/power/energy_model.c
> +++ b/kernel/power/energy_model.c
> @@ -1000,3 +1000,37 @@ void em_rebuild_sched_domains(void)
> */
> schedule_work(&rebuild_sd_work);
> }
> +
> +int for_each_em_perf_domain(int (*cb)(struct em_perf_domain*, void *),
> + void *data)
> +{
> + struct em_perf_domain *pd;
> +
> + lockdep_assert_not_held(&em_pd_mutex);
> + guard(mutex)(&em_pd_list_mutex);
> +
> + list_for_each_entry(pd, &em_pd_list, node) {
> + int ret;
> +
> + ret = cb(pd, data);
> + if (ret)
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +struct em_perf_domain *em_perf_domain_get_by_id(int id)
> +{
> + struct em_perf_domain *pd;
> +
> + lockdep_assert_not_held(&em_pd_mutex);
> + guard(mutex)(&em_pd_list_mutex);
> +
> + list_for_each_entry(pd, &em_pd_list, node) {
> + if (pd->id == id)
> + return pd;
> + }
> +
> + return NULL;
> +}
That code looks good, you can keep it. Although, please
add the comments above these functions that they are
only used locally as helpers for the notifications.