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

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Date:   Tue, 28 Jun 2022 09:49:46 +0800
From:   Peter Wang <peter.wang@...iatek.com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     <matthias.bgg@...il.com>, <len.brown@...el.com>, <pavel@....cz>,
        <rafael@...nel.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>,
        <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


On 6/27/22 10:14 PM, Greg KH wrote:
> On Mon, Jun 13, 2022 at 08:07:55PM +0800, 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)
> This is just making this horrible api even worse.  Now there are 2
> boolean flags required, 2 more than really should even be here at all.
> Every time you see this function being used, you will now have to look
> up the definition  to see what it really does.
>
> Please make a new function that calls the internal function with the
> flag set properly, so that it is obvious what is happening when the call
> is made.
>
> and really, the same thing should be done for the check_idle flag,
> that's not good either.
>
> thanks,

Hi Gerg,

Good point! you are right, I wont change api next version

Thank you for review


> greg k-h