Re: [PATCH V6 03/10] PM / Domains: Add function to remove a pm-domain
From: Ulf Hansson <hidden>
Date: 2016-02-29 13:45:17
Also in:
linux-pm, linux-tegra
Possibly related (same subject, not in this thread)
- 2016-02-29 · Re: [PATCH V6 03/10] PM / Domains: Add function to remove a pm-domain · Jon Hunter <hidden>
On 26 February 2016 at 16:48, Jon Hunter [off-list ref] 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.
In general I think you can work a bit on the changelog, for example split it into a few sections to make it more readable. I would like it to state clearly what constraint we have to be able to remove a PM domain. More precisely, the device structure is needed, no of genpd provider etc. Maybe also "linked to another domain" can be rephrased to tell about both masters and subdomains. Finally, perhaps change terminology for the "power-domain" to "PM domain" as I think that's more widely used.
quoted hunk ↗ jump to hunk
Signed-off-by: Jon Hunter <jonathanh@nvidia.com> --- drivers/base/power/domain.c | 31 +++++++++++++++++++++++++++++++ include/linux/pm_domain.h | 5 +++++ 2 files changed, 36 insertions(+)diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c index 608bc00655ee..22f6e9d738bf 100644 --- a/drivers/base/power/domain.c +++ b/drivers/base/power/domain.c@@ -1557,6 +1557,37 @@ 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) +{ + int ret = 0; + + if (IS_ERR_OR_NULL(genpd)) + return -EINVAL; + + mutex_lock(&gpd_list_lock); + mutex_lock(&genpd->lock); + + if (!list_empty(&genpd->master_links) + || !list_empty(&genpd->slave_links) || genpd->device_count) { + ret = -EBUSY; + goto out; + } + + cancel_work_sync(&genpd->power_off_work);
This can deadlock as the work function tries to lock the genpd mutex. I suggest to move this outside of the locking section just before returning, but of course still only in case of a non-error.
+ list_del(&genpd->gpd_list_node); + +out: + mutex_unlock(&genpd->lock); + mutex_unlock(&gpd_list_lock); +
Besides the minor comment above. 1) Have you considered how to protects against a registered of_genpd_provider for the genpd? 2) Theoretically some could call pm_genpd_add_subdomain() after this point. I guess we can consider that as an abuse of the API, although do you think we need to protect that from really happening?
quoted hunk ↗ jump to hunk
+ return ret; +} +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 b38dd74dea9b..9ae9c42f807f 100644 --- a/include/linux/pm_domain.h +++ b/include/linux/pm_domain.h@@ -134,6 +134,7 @@ 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;@@ -177,6 +178,10 @@ 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