linux-kernel - Re: [PATCH v1] PM-runtime: Check supplier

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Date:   Wed, 22 Jun 2022 14:09:16 +0800
From:   Peter Wang <peter.wang@...iatek.com>
To:     <matthias.bgg@...il.com>, <len.brown@...el.com>, <pavel@....cz>,
        <rafael@...nel.org>, <gregkh@...uxfoundation.org>,
        <stanley.chu@...iatek.com>, <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-pm@...r.kernel.org>,
        <martin.petersen@...cle.com>, <avri.altman@....com>,
        <alim.akhtar@...sung.com>, <jejb@...ux.ibm.com>
CC:     <wsd_upstream@...iatek.com>, <linux-mediatek@...ts.infradead.org>,
        <chun-hung.wu@...iatek.com>, <alice.chao@...iatek.com>,
        <cc.chou@...iatek.com>, <chaotian.jing@...iatek.com>,
        <jiajie.hao@...iatek.com>, <powen.kao@...iatek.com>,
        <qilin.tan@...iatek.com>, <lin.gui@...iatek.com>,
        <tun-yu.yu@...iatek.com>
Subject: Re: [PATCH v1] PM-runtime: Check supplier_preactivated before release
 supplier

Hi all,


gentle ping for this bug fix review.


Thanks.


On 6/13/22 8:07 PM, peter.wang@...iatek.com wrote:
> From: Peter Wang <peter.wang@...iatek.com>
>
> With divice link of DL_FLAG_PM_RUNTIME, if consumer call pm_runtime_get_suppliers
> to prevent supplier enter suspend, pm_runtime_release_supplier should
> check supplier_preactivated before let supplier enter suspend.
>
> If the link is drop or release, bypass check supplier_preactivated.
>
> Signed-off-by: Peter Wang <peter.wang@...iatek.com>
> ---
>   drivers/base/core.c          |  2 +-
>   drivers/base/power/runtime.c | 15 ++++++++++++---
>   include/linux/pm_runtime.h   |  5 +++--
>   3 files changed, 16 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 7cd789c4985d..3b9cc559928f 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -486,7 +486,7 @@ static void device_link_release_fn(struct work_struct *work)
>   	/* Ensure that all references to the link object have been dropped. */
>   	device_link_synchronize_removal();
>   
> -	pm_runtime_release_supplier(link, true);
> +	pm_runtime_release_supplier(link, true, true);
>   
>   	put_device(link->consumer);
>   	put_device(link->supplier);
> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> index 676dc72d912d..3c4f425937a1 100644
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -314,10 +314,19 @@ static int rpm_get_suppliers(struct device *dev)
>    * and if @check_idle is set, check if that device is idle (and so it can be
>    * suspended).
>    */
> -void pm_runtime_release_supplier(struct device_link *link, bool check_idle)
> +void pm_runtime_release_supplier(struct device_link *link, bool check_idle,
> +	bool drop)
>   {
>   	struct device *supplier = link->supplier;
>   
> +	/*
> +	 * When consumer hold supplier, supplier cannot enter suspend.
> +	 * Driect release supplier and let supplier enter suspend is not allow.
> +	 * Unless the link is drop, direct relsease supplier should be okay.
> +	 */
> +	if (link->supplier_preactivated && !drop)
> +		return;
> +
>   	/*
>   	 * The additional power.usage_count check is a safety net in case
>   	 * the rpm_active refcount becomes saturated, in which case
> @@ -338,7 +347,7 @@ static void __rpm_put_suppliers(struct device *dev, bool try_to_suspend)
>   
>   	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
>   				device_links_read_lock_held())
> -		pm_runtime_release_supplier(link, try_to_suspend);
> +		pm_runtime_release_supplier(link, try_to_suspend, false);
>   }
>   
>   static void rpm_put_suppliers(struct device *dev)
> @@ -1838,7 +1847,7 @@ void pm_runtime_drop_link(struct device_link *link)
>   		return;
>   
>   	pm_runtime_drop_link_count(link->consumer);
> -	pm_runtime_release_supplier(link, true);
> +	pm_runtime_release_supplier(link, true, true);
>   }
>   
>   static bool pm_runtime_need_not_resume(struct device *dev)
> diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
> index 9e4d056967c6..354ffb1eaec0 100644
> --- a/include/linux/pm_runtime.h
> +++ b/include/linux/pm_runtime.h
> @@ -88,7 +88,8 @@ extern void pm_runtime_get_suppliers(struct device *dev);
>   extern void pm_runtime_put_suppliers(struct device *dev);
>   extern void pm_runtime_new_link(struct device *dev);
>   extern void pm_runtime_drop_link(struct device_link *link);
> -extern void pm_runtime_release_supplier(struct device_link *link, bool check_idle);
> +extern void pm_runtime_release_supplier(struct device_link *link,
> +	bool check_idle, bool drop);
>   
>   extern int devm_pm_runtime_enable(struct device *dev);
>   
> @@ -315,7 +316,7 @@ static inline void pm_runtime_put_suppliers(struct device *dev) {}
>   static inline void pm_runtime_new_link(struct device *dev) {}
>   static inline void pm_runtime_drop_link(struct device_link *link) {}
>   static inline void pm_runtime_release_supplier(struct device_link *link,
> -					       bool check_idle) {}
> +					       bool check_idle, bool drop) {}
>   
>   #endif /* !CONFIG_PM */
>