linux-kernel - Re: [PATCH] PM: domains: create debugfs nodes when adding power domains

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Date:   Fri, 4 Dec 2020 15:49:59 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Thierry Strudel <tstrudel@...gle.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PM: domains: create debugfs nodes when adding power domains

On Fri, 4 Dec 2020 at 00:35, Thierry Strudel <tstrudel@...gle.com> wrote:
>
> debugfs nodes were created in genpd_debug_init alled in late_initcall
> preventing power domains registered though loadable modules to have
> a debugfs entry.
>
> Create/remove debugfs nodes when the power domain is added/removed
> to/from the internal gpd_list.
>
> Signed-off-by: Thierry Strudel <tstrudel@...gle.com>
> ---
>  drivers/base/power/domain.c | 61 ++++++++++++++++++++++++-------------
>  1 file changed, 39 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 743268996336..3f168ec93762 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -1880,6 +1880,8 @@ static void genpd_lock_init(struct generic_pm_domain *genpd)
>         }
>  }
>
> +static void genpd_debug_add(struct generic_pm_domain *genpd);
> +
>  /**
>   * pm_genpd_init - Initialize a generic I/O PM domain object.
>   * @genpd: PM domain object to initialize.
> @@ -1954,12 +1956,15 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
>
>         mutex_lock(&gpd_list_lock);
>         list_add(&genpd->gpd_list_node, &gpd_list);
> +       genpd_debug_add(genpd);
>         mutex_unlock(&gpd_list_lock);
>
>         return 0;
>  }
>  EXPORT_SYMBOL_GPL(pm_genpd_init);
>
> +static void genpd_debug_remove(struct generic_pm_domain *genpd);
> +

Please avoid these forward declarations. I think it's better to move
the code around.

>  static int genpd_remove(struct generic_pm_domain *genpd)
>  {
>         struct gpd_link *l, *link;
> @@ -1987,6 +1992,7 @@ static int genpd_remove(struct generic_pm_domain *genpd)
>                 kfree(link);
>         }
>
> +       genpd_debug_remove(genpd);
>         list_del(&genpd->gpd_list_node);
>         genpd_unlock(genpd);
>         cancel_work_sync(&genpd->power_off_work);
> @@ -3177,36 +3183,44 @@ DEFINE_SHOW_ATTRIBUTE(total_idle_time);
>  DEFINE_SHOW_ATTRIBUTE(devices);
>  DEFINE_SHOW_ATTRIBUTE(perf_state);
>
> -static int __init genpd_debug_init(void)
> +static void genpd_debug_add(struct generic_pm_domain *genpd)
>  {
>         struct dentry *d;
> -       struct generic_pm_domain *genpd;
>
> +       d = debugfs_create_dir(genpd->name, genpd_debugfs_dir);

What happens if "genpd_debugfs_dir" is NULL, which will be the case
until the late_initcall(genpd_debug_init) has been executed!?

> +
> +       debugfs_create_file("current_state", 0444,
> +                           d, genpd, &status_fops);
> +       debugfs_create_file("sub_domains", 0444,
> +                           d, genpd, &sub_domains_fops);
> +       debugfs_create_file("idle_states", 0444,
> +                           d, genpd, &idle_states_fops);
> +       debugfs_create_file("active_time", 0444,
> +                           d, genpd, &active_time_fops);
> +       debugfs_create_file("total_idle_time", 0444,
> +                           d, genpd, &total_idle_time_fops);
> +       debugfs_create_file("devices", 0444,
> +                           d, genpd, &devices_fops);
> +       if (genpd->set_performance_state)
> +               debugfs_create_file("perf_state", 0444,
> +                                   d, genpd, &perf_state_fops);
> +}

[...]

Kind regards
Uffe