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    SubjectRe: [PATCH] PM / OPP: Implement free_opp_table function
    On 05/16/2014 04:09 AM, Inderpal Singh wrote:
    > At the driver unloading time the associated opp table may need
    > to be deleted. Otherwise it amounts to memory leak. The existing
    > OPP library does not have provison to do so.
    >
    > Hence this patch implements the function to free the opp table.
    >
    > Signed-off-by: Inderpal Singh <inderpal.s@samsung.com>
    > ---
    > drivers/base/power/opp.c | 41 +++++++++++++++++++++++++++++++++++++++++
    > include/linux/pm_opp.h | 6 ++++++
    > 2 files changed, 47 insertions(+)
    >
    > diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
    > index d9e376a..d45ffd5 100644
    > --- a/drivers/base/power/opp.c
    > +++ b/drivers/base/power/opp.c
    > @@ -654,4 +654,45 @@ int of_init_opp_table(struct device *dev)
    > return 0;
    > }
    > EXPORT_SYMBOL_GPL(of_init_opp_table);
    > +
    > +/**
    > + * dev_pm_opp_free_opp_table() - free the opp table
    > + * @dev: device for which we do this operation
    > + *
    > + * Free up the allocated opp table
    > + *
    > + * Locking: The internal device_opp and opp structures are RCU protected.
    > + * Hence this function internally uses RCU updater strategy with mutex locks to
    > + * keep the integrity of the internal data structures. Callers should ensure
    > + * that this function is *NOT* called under RCU protection or in contexts where
    > + * mutex locking or synchronize_rcu() blocking calls cannot be used.
    > + */
    > +void dev_pm_opp_free_opp_table(struct device *dev)
    > +{
    > + struct device_opp *dev_opp = NULL;
    > + struct dev_pm_opp *opp;
    > +
    if (!dev)
    return;

    > + /* Hold our list modification lock here */
    > + mutex_lock(&dev_opp_list_lock);
    > +
    > + /* Check for existing list for 'dev' */
    > + dev_opp = find_device_opp(dev);
    > + if (IS_ERR(dev_opp)) {
    > + mutex_unlock(&dev_opp_list_lock);
    > + return;
    > + }
    > +
    > + while (!list_empty(&dev_opp->opp_list)) {
    > + opp = list_entry_rcu(dev_opp->opp_list.next,
    > + struct dev_pm_opp, node);
    > + list_del_rcu(&opp->node);
    > + kfree_rcu(opp, head);
    > + }

    How about the OPP notifiers? should'nt we add a new event
    OPP_EVENT_REMOVE?

    To maintain non-dt behavior coherency, should'nt we rather add a
    opp_remove or an opp_del function?

    > +
    > + list_del_rcu(&dev_opp->node);
    > + mutex_unlock(&dev_opp_list_lock);
    > + synchronize_rcu();
    > + kfree(dev_opp);
    > +}
    > +EXPORT_SYMBOL_GPL(dev_pm_opp_free_opp_table);
    > #endif
    > diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
    > index 0330217..3c29620 100644
    > --- a/include/linux/pm_opp.h
    > +++ b/include/linux/pm_opp.h
    > @@ -50,6 +50,8 @@ int dev_pm_opp_enable(struct device *dev, unsigned long freq);
    > int dev_pm_opp_disable(struct device *dev, unsigned long freq);
    >
    > struct srcu_notifier_head *dev_pm_opp_get_notifier(struct device *dev);
    > +
    > +void dev_pm_opp_free_opp_table(struct device *dev);
    > #else
    > static inline unsigned long dev_pm_opp_get_voltage(struct dev_pm_opp *opp)
    > {
    > @@ -105,6 +107,10 @@ static inline struct srcu_notifier_head *dev_pm_opp_get_notifier(
    > {
    > return ERR_PTR(-EINVAL);
    > }
    > +
    > +void dev_pm_opp_free_opp_table(struct device *dev)
    > +{
    > +}
    > #endif /* CONFIG_PM_OPP */
    >
    > #if defined(CONFIG_PM_OPP) && defined(CONFIG_OF)
    >


    --
    Regards,
    Nishanth Menon


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