Re: [PATCH 03/10] OPP: Allocate dev_opp from _add_device_opp()

Stephen Boyd
2015-07-02T01:02:43Z

On 06/15/2015 04:57 AM, Viresh Kumar wrote:
> There is no need to complicate _opp_add_dynamic() with allocation of
> dev_opp as well. Allocate it from _add_device_opp() instead.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> drivers/base/power/opp.c | 39 +++++++++++++++++++--------------------
> 1 file changed, 19 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
> index 7895fdd64192..4b646f36f252 100644
> --- a/drivers/base/power/opp.c
> +++ b/drivers/base/power/opp.c
> @@ -408,11 +408,11 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev,
> EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor);
>
> /**
> - * _add_device_opp() - Allocate a new device OPP table
> + * _add_device_opp() - Returns device OPP table

Find device OPP table, or allocate a new one?

> * @dev: device for which we do this operation
> *
> - * New device node which uses OPPs - used when multiple devices with OPP tables
> - * are maintained.
> + * It tries to find an existing table first, if it couldn't find one, it
> + * allocates a new OPP table and returns that.
> *
> * Return: valid device_opp pointer if success, else NULL.
> */
> @@ -420,6 +420,11 @@ static struct device_opp *_add_device_opp(struct device *dev)
> {
> struct device_opp *dev_opp;
>
> + /* Check for existing list for 'dev' first */
> + dev_opp = _find_device_opp(dev);
> + if (!IS_ERR(dev_opp))
> + return dev_opp;
> +
> /*
> * Allocate a new device OPP table. In the infrequent case where a new
> * device is needed to be added, we pay this penalty.
> @@ -575,8 +580,8 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_remove);
> static int _opp_add_dynamic(struct device *dev, unsigned long freq,
> long u_volt, bool dynamic)
> {
> - struct device_opp *dev_opp = NULL;
> - struct dev_pm_opp *opp, *new_opp;
> + struct device_opp *dev_opp;
> + struct dev_pm_opp *opp = NULL, *new_opp;

Hm...

> struct list_head *head;
> int ret;
>
> @@ -592,19 +597,11 @@ static int _opp_add_dynamic(struct device *dev, unsigned long freq,
> new_opp->rate = freq;
> new_opp->u_volt = u_volt;
> new_opp->available = true;
> - new_opp->dynamic = dynamic;
>
> - /* Check for existing list for 'dev' */
> - dev_opp = _find_device_opp(dev);
> - if (IS_ERR(dev_opp)) {
> - dev_opp = _add_device_opp(dev);
> - if (!dev_opp) {
> - ret = -ENOMEM;
> - goto free_opp;
> - }
> -
> - head = &dev_opp->opp_list;
> - goto list_add;
> + dev_opp = _add_device_opp(dev);
> + if (!dev_opp) {
> + ret = -ENOMEM;
> + goto free_opp;
> }
>
> /*
> @@ -620,17 +617,17 @@ static int _opp_add_dynamic(struct device *dev, unsigned long freq,
> }
>
> /* Duplicate OPPs ? */
> - if (new_opp->rate == opp->rate) {
> + if (opp && new_opp->rate == opp->rate) {

Isn't opp always non-NULL at this point? Maybe this if statement should
be moved into the list_for_each_entry_rcu() loop.

> ret = opp->available && new_opp->u_volt == opp->u_volt ?
> 0 : -EEXIST;
>
> dev_warn(dev, "%s: duplicate OPPs detected. Existing: freq: %lu, volt: %lu, enabled: %d. New: freq: %lu, volt: %lu, enabled: %d\n",
> __func__, opp->rate, opp->u_volt, opp->available,
> new_opp->rate, new_opp->u_volt, new_opp->available);
> - goto free_opp;
> + goto remove_dev_opp;
> }
>
> -list_add:
> + new_opp->dynamic = dynamic;
> new_opp->dev_opp = dev_opp;
> list_add_rcu(&new_opp->node, head);
> mutex_unlock(&dev_opp_list_lock);
> @@ -642,6 +639,8 @@ static int _opp_add_dynamic(struct device *dev, unsigned long freq,
> srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_ADD, new_opp);
> return 0;
>
> +remove_dev_opp:
> + _remove_device_opp(dev_opp);

Doesn't this just return early because dev_opp has something in it?

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