| Message ID | 1453998832-27383-9-git-send-email-jonathanh@nvidia.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On 28 January 2016 at 17:33, Jon Hunter <jonathanh@nvidia.com> wrote: > The genpd framework allows users to add power-domains via the > pm_genpd_init() function, however, there is no corresponding function > to remove a power-domain. For most devices this may be fine as the power > domains are never removed, however, for devices that wish to populate > the power-domains from within a driver, having the ability to remove a > power domain if the probing of the device fails or the driver is unloaded > is necessary. Therefore, add a function to remove a power-domain. Please > note that the power domain can only be removed if there are no devices > using the power-domain and it is not linked to another domain. > > Signed-off-by: Jon Hunter <jonathanh@nvidia.com> > --- > drivers/base/power/domain.c | 26 ++++++++++++++++++++++++++ > include/linux/pm_domain.h | 5 +++++ > 2 files changed, 31 insertions(+) > > diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c > index 45e3641b427d..b4120121bcac 100644 > --- a/drivers/base/power/domain.c > +++ b/drivers/base/power/domain.c > @@ -1529,6 +1529,32 @@ void pm_genpd_init(struct generic_pm_domain *genpd, > } > EXPORT_SYMBOL_GPL(pm_genpd_init); > > +/** > + * pm_genpd_remove - Remove a generic I/O PM domain object. > + * @genpd: PM domain object to remove. > + */ > +int pm_genpd_remove(struct generic_pm_domain *genpd) > +{ > + if (IS_ERR_OR_NULL(genpd)) > + return -EINVAL; > + > + mutex_lock(&genpd->lock); pm_genpd_summary_show() first locks the gpd_list_lock, then the genpd lock. Please preserve that order here as well, to prevent potential deadlocks. > + > + if (!list_empty(&genpd->master_links) > + || !list_empty(&genpd->slave_links) || genpd->device_count) { > + mutex_unlock(&genpd->lock); > + return -EBUSY; > + } > + > + mutex_lock_nested(&gpd_list_lock, SINGLE_DEPTH_NESTING); Why the nesting, can this really cause lockdep warnings? > + list_del(&genpd->gpd_list_node); > + mutex_unlock(&gpd_list_lock); > + mutex_unlock(&genpd->lock); Before returning, you need to make sure there isn't a scheduled work for powering off the genpd. That might happen for example happen via genpd_poweroff_unused(). Otherwise, the caller of pm_genpd_remove() might free the memory while the genpd struct is still in use... I assume a cancel_delayed_work_sync() should do the trick here. > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(pm_genpd_remove); > + > #ifdef CONFIG_PM_GENERIC_DOMAINS_OF > /* > * Device Tree based PM domain providers. > diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h > index db21d3995f7e..0d661998fa74 100644 > --- a/include/linux/pm_domain.h > +++ b/include/linux/pm_domain.h > @@ -123,6 +123,7 @@ extern int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd, > struct generic_pm_domain *target); > extern void pm_genpd_init(struct generic_pm_domain *genpd, > struct dev_power_governor *gov, bool is_off); > +extern int pm_genpd_remove(struct generic_pm_domain *genpd); > > extern struct dev_power_governor simple_qos_governor; > extern struct dev_power_governor pm_domain_always_on_gov; > @@ -161,6 +162,10 @@ static inline void pm_genpd_init(struct generic_pm_domain *genpd, > struct dev_power_governor *gov, bool is_off) > { > } > +static inline int pm_genpd_remove(struct generic_pm_domain *genpd) > +{ > + return -ENOTSUPP; > +} > #endif > > static inline int pm_genpd_add_device(struct generic_pm_domain *genpd, > -- > 2.1.4 > Kind regards Uffe -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 02/02/16 15:35, Ulf Hansson wrote: > On 28 January 2016 at 17:33, Jon Hunter <jonathanh@nvidia.com> wrote: >> The genpd framework allows users to add power-domains via the >> pm_genpd_init() function, however, there is no corresponding function >> to remove a power-domain. For most devices this may be fine as the power >> domains are never removed, however, for devices that wish to populate >> the power-domains from within a driver, having the ability to remove a >> power domain if the probing of the device fails or the driver is unloaded >> is necessary. Therefore, add a function to remove a power-domain. Please >> note that the power domain can only be removed if there are no devices >> using the power-domain and it is not linked to another domain. >> >> Signed-off-by: Jon Hunter <jonathanh@nvidia.com> >> --- >> drivers/base/power/domain.c | 26 ++++++++++++++++++++++++++ >> include/linux/pm_domain.h | 5 +++++ >> 2 files changed, 31 insertions(+) >> >> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c >> index 45e3641b427d..b4120121bcac 100644 >> --- a/drivers/base/power/domain.c >> +++ b/drivers/base/power/domain.c >> @@ -1529,6 +1529,32 @@ void pm_genpd_init(struct generic_pm_domain *genpd, >> } >> EXPORT_SYMBOL_GPL(pm_genpd_init); >> >> +/** >> + * pm_genpd_remove - Remove a generic I/O PM domain object. >> + * @genpd: PM domain object to remove. >> + */ >> +int pm_genpd_remove(struct generic_pm_domain *genpd) >> +{ >> + if (IS_ERR_OR_NULL(genpd)) >> + return -EINVAL; >> + >> + mutex_lock(&genpd->lock); > > pm_genpd_summary_show() first locks the gpd_list_lock, then the genpd lock. > > Please preserve that order here as well, to prevent potential deadlocks. Ok, yes good point. >> + >> + if (!list_empty(&genpd->master_links) >> + || !list_empty(&genpd->slave_links) || genpd->device_count) { >> + mutex_unlock(&genpd->lock); >> + return -EBUSY; >> + } >> + >> + mutex_lock_nested(&gpd_list_lock, SINGLE_DEPTH_NESTING); > > Why the nesting, can this really cause lockdep warnings? Hmmm, yes I don't believe that is needed here as it should be a different class. Will fix. >> + list_del(&genpd->gpd_list_node); >> + mutex_unlock(&gpd_list_lock); >> + mutex_unlock(&genpd->lock); > > Before returning, you need to make sure there isn't a scheduled work > for powering off the genpd. > That might happen for example happen via genpd_poweroff_unused(). > > Otherwise, the caller of pm_genpd_remove() might free the memory while > the genpd struct is still in use... > > I assume a cancel_delayed_work_sync() should do the trick here. Good point. I will address that too. Jon -- To unsubscribe from this list: send the line "unsubscribe linux-pm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c index 45e3641b427d..b4120121bcac 100644 --- a/drivers/base/power/domain.c +++ b/drivers/base/power/domain.c @@ -1529,6 +1529,32 @@ void pm_genpd_init(struct generic_pm_domain *genpd, } EXPORT_SYMBOL_GPL(pm_genpd_init); +/** + * pm_genpd_remove - Remove a generic I/O PM domain object. + * @genpd: PM domain object to remove. + */ +int pm_genpd_remove(struct generic_pm_domain *genpd) +{ + if (IS_ERR_OR_NULL(genpd)) + return -EINVAL; + + mutex_lock(&genpd->lock); + + if (!list_empty(&genpd->master_links) + || !list_empty(&genpd->slave_links) || genpd->device_count) { + mutex_unlock(&genpd->lock); + return -EBUSY; + } + + mutex_lock_nested(&gpd_list_lock, SINGLE_DEPTH_NESTING); + list_del(&genpd->gpd_list_node); + mutex_unlock(&gpd_list_lock); + mutex_unlock(&genpd->lock); + + return 0; +} +EXPORT_SYMBOL_GPL(pm_genpd_remove); + #ifdef CONFIG_PM_GENERIC_DOMAINS_OF /* * Device Tree based PM domain providers. diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h index db21d3995f7e..0d661998fa74 100644 --- a/include/linux/pm_domain.h +++ b/include/linux/pm_domain.h @@ -123,6 +123,7 @@ extern int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd, struct generic_pm_domain *target); extern void pm_genpd_init(struct generic_pm_domain *genpd, struct dev_power_governor *gov, bool is_off); +extern int pm_genpd_remove(struct generic_pm_domain *genpd); extern struct dev_power_governor simple_qos_governor; extern struct dev_power_governor pm_domain_always_on_gov; @@ -161,6 +162,10 @@ static inline void pm_genpd_init(struct generic_pm_domain *genpd, struct dev_power_governor *gov, bool is_off) { } +static inline int pm_genpd_remove(struct generic_pm_domain *genpd) +{ + return -ENOTSUPP; +} #endif static inline int pm_genpd_add_device(struct generic_pm_domain *genpd,
The genpd framework allows users to add power-domains via the pm_genpd_init() function, however, there is no corresponding function to remove a power-domain. For most devices this may be fine as the power domains are never removed, however, for devices that wish to populate the power-domains from within a driver, having the ability to remove a power domain if the probing of the device fails or the driver is unloaded is necessary. Therefore, add a function to remove a power-domain. Please note that the power domain can only be removed if there are no devices using the power-domain and it is not linked to another domain. Signed-off-by: Jon Hunter <jonathanh@nvidia.com> --- drivers/base/power/domain.c | 26 ++++++++++++++++++++++++++ include/linux/pm_domain.h | 5 +++++ 2 files changed, 31 insertions(+)