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Date: Mon, 16 Oct 2023 12:11:49 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Viresh Kumar <viresh.kumar@...aro.org>
Cc: Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
Stephen Boyd <sboyd@...nel.org>, linux-pm@...r.kernel.org,
Vincent Guittot <vincent.guittot@...aro.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] OPP: Remove genpd_virt_dev_lock
On Fri, 13 Oct 2023 at 10:49, Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> All the config operations for OPP tables share common code paths now and
> none of the other ones have such protection in place. Either all should
> have it or none.
>
> The understanding here is that user won't clear the OPP configs while
> still using them and so such a case won't happen. We can always come
> back and use a wider lock for all resource types if required.
>
> Also fix the error on failing to allocate memory.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>
Kind regards
Uffe
> ---
> drivers/opp/core.c | 33 +++------------------------------
> drivers/opp/opp.h | 2 --
> 2 files changed, 3 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/opp/core.c b/drivers/opp/core.c
> index 3516e79cf743..befe46036ad5 100644
> --- a/drivers/opp/core.c
> +++ b/drivers/opp/core.c
> @@ -1089,12 +1089,6 @@ static int _opp_set_required_opps_genpd(struct device *dev,
> delta = -1;
> }
>
> - /*
> - * Acquire genpd_virt_dev_lock to make sure we don't use a genpd_dev
> - * after it is freed from another thread.
> - */
> - mutex_lock(&opp_table->genpd_virt_dev_lock);
> -
> while (index != target) {
> ret = _set_performance_state(dev, genpd_virt_devs[index], opp, index);
> if (ret)
> @@ -1103,8 +1097,6 @@ static int _opp_set_required_opps_genpd(struct device *dev,
> index += delta;
> }
>
> - mutex_unlock(&opp_table->genpd_virt_dev_lock);
> -
> return 0;
> }
>
> @@ -1474,7 +1466,6 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index)
> return ERR_PTR(-ENOMEM);
>
> mutex_init(&opp_table->lock);
> - mutex_init(&opp_table->genpd_virt_dev_lock);
> INIT_LIST_HEAD(&opp_table->dev_list);
> INIT_LIST_HEAD(&opp_table->lazy);
>
> @@ -1510,7 +1501,6 @@ static struct opp_table *_allocate_opp_table(struct device *dev, int index)
> remove_opp_dev:
> _of_clear_opp_table(opp_table);
> _remove_opp_dev(opp_dev, opp_table);
> - mutex_destroy(&opp_table->genpd_virt_dev_lock);
> mutex_destroy(&opp_table->lock);
> err:
> kfree(opp_table);
> @@ -1678,7 +1668,6 @@ static void _opp_table_kref_release(struct kref *kref)
> list_for_each_entry_safe(opp_dev, temp, &opp_table->dev_list, node)
> _remove_opp_dev(opp_dev, opp_table);
>
> - mutex_destroy(&opp_table->genpd_virt_dev_lock);
> mutex_destroy(&opp_table->lock);
> kfree(opp_table);
> }
> @@ -2395,7 +2384,7 @@ static void _opp_put_config_regulators_helper(struct opp_table *opp_table)
> opp_table->config_regulators = NULL;
> }
>
> -static void _detach_genpd(struct opp_table *opp_table)
> +static void _opp_detach_genpd(struct opp_table *opp_table)
> {
> int index;
>
> @@ -2449,13 +2438,11 @@ static int _opp_attach_genpd(struct opp_table *opp_table, struct device *dev,
> if (!opp_table->required_opp_count)
> return -EPROBE_DEFER;
>
> - mutex_lock(&opp_table->genpd_virt_dev_lock);
> -
> opp_table->genpd_virt_devs = kcalloc(opp_table->required_opp_count,
> sizeof(*opp_table->genpd_virt_devs),
> GFP_KERNEL);
> if (!opp_table->genpd_virt_devs)
> - goto unlock;
> + return -ENOMEM;
>
> while (*name) {
> if (index >= opp_table->required_opp_count) {
> @@ -2478,29 +2465,15 @@ static int _opp_attach_genpd(struct opp_table *opp_table, struct device *dev,
>
> if (virt_devs)
> *virt_devs = opp_table->genpd_virt_devs;
> - mutex_unlock(&opp_table->genpd_virt_dev_lock);
>
> return 0;
>
> err:
> - _detach_genpd(opp_table);
> -unlock:
> - mutex_unlock(&opp_table->genpd_virt_dev_lock);
> + _opp_detach_genpd(opp_table);
> return ret;
>
> }
>
> -static void _opp_detach_genpd(struct opp_table *opp_table)
> -{
> - /*
> - * Acquire genpd_virt_dev_lock to make sure virt_dev isn't getting
> - * used in parallel.
> - */
> - mutex_lock(&opp_table->genpd_virt_dev_lock);
> - _detach_genpd(opp_table);
> - mutex_unlock(&opp_table->genpd_virt_dev_lock);
> -}
> -
> static void _opp_clear_config(struct opp_config_data *data)
> {
> if (data->flags & OPP_CONFIG_GENPD)
> diff --git a/drivers/opp/opp.h b/drivers/opp/opp.h
> index fefdf9845692..08366f90f16b 100644
> --- a/drivers/opp/opp.h
> +++ b/drivers/opp/opp.h
> @@ -160,7 +160,6 @@ enum opp_table_access {
> * @rate_clk_single: Currently configured frequency for single clk.
> * @current_opp: Currently configured OPP for the table.
> * @suspend_opp: Pointer to OPP to be used during device suspend.
> - * @genpd_virt_dev_lock: Mutex protecting the genpd virtual device pointers.
> * @genpd_virt_devs: List of virtual devices for multiple genpd support.
> * @required_opp_tables: List of device OPP tables that are required by OPPs in
> * this table.
> @@ -212,7 +211,6 @@ struct opp_table {
> struct dev_pm_opp *current_opp;
> struct dev_pm_opp *suspend_opp;
>
> - struct mutex genpd_virt_dev_lock;
> struct device **genpd_virt_devs;
> struct opp_table **required_opp_tables;
> unsigned int required_opp_count;
> --
> 2.31.1.272.g89b43f80a514
>
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