linux-kernel - Re: [PATCH v2] ACPI: scan: Use async schedule function for acpi_scan_clear_dep

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Message-Id: <95a76a02-d9b3-494c-86fc-bb7517117d80@picoheart.com>
Date: Wed, 28 Jan 2026 14:21:52 +0800
From: "Yicong Yang" <yang.yicong@...oheart.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: <yang.yicong@...oheart.com>, <lenb@...nel.org>, <tglx@...nel.org>, 
	<gregkh@...uxfoundation.org>, <dakr@...nel.org>, 
	<akpm@...ux-foundation.org>, <apatel@...tanamicro.com>, <pjw@...nel.org>, 
	<palmer@...belt.com>, <aou@...s.berkeley.edu>, <alex@...ti.fr>, 
	<geshijian@...oheart.com>, <weidong.wd@...oheart.com>, 
	<linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>, 
	<linux-riscv@...ts.infradead.org>
Subject: Re: [PATCH v2] ACPI: scan: Use async schedule function for acpi_scan_clear_dep_fn

On 1/28/26 4:56 AM, Rafael J. Wysocki wrote:
> On Mon, Jan 26, 2026 at 8:04 AM Yicong Yang <yang.yicong@...oheart.com> wrote:
>>

[...]

>>  static bool acpi_scan_clear_dep_queue(struct acpi_device *adev)
>>  {
>> -       struct acpi_scan_clear_dep_work *cdw;
>> -
>>         if (adev->dep_unmet)
>>                 return false;
>>
>> -       cdw = kmalloc(sizeof(*cdw), GFP_KERNEL);
>> -       if (!cdw)
>> -               return false;
>> -
>> -       cdw->adev = adev;
>> -       INIT_WORK(&cdw->work, acpi_scan_clear_dep_fn);
>>         /*
>> -        * Since the work function may block on the lock until the entire
>> -        * initial enumeration of devices is complete, put it into the unbound
>> -        * workqueue.
>> +        * Async schedule the deferred acpi_scan_clear_dep_fn() since:
>> +        * - acpi_bus_attach() needs to hold acpi_scan_lock which cannot
>> +        *   be acquired under acpi_dep_list_lock (held here)
>> +        * - the deferred work at boot stage is ensured to be finished
>> +        *   before userspace init task by the async_synchronize_full()
>> +        *   barrier
>> +        *
>> +        * Use _nocall variant since it'll return on failure instead of
>> +        * run the function synchronously.
>>          */
>> -       queue_work(system_dfl_wq, &cdw->work);
>> +       if (!async_schedule_dev_nocall(acpi_scan_clear_dep_fn, &adev->dev))
>> +               return false;
>>
>>         return true;
> 
> What about doing
> 
>     return !!async_schedule_dev_nocall(acpi_scan_clear_dep_fn, &adev->dev);
> 
> here?
> 

sure, will update. the '!!' conversion could be dropped as
async_schedule_dev_nocall also returns boolean.

thanks.