linux-kernel - Re: [PATCH v8 07/22] ACPI: Separate acpi_bus

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Date:	Sat, 12 Jan 2013 23:40:32 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>, Len Brown <lenb@...nel.org>,
	Taku Izumi <izumi.taku@...fujitsu.com>,
	Jiang Liu <jiang.liu@...wei.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: Re: [PATCH v8 07/22] ACPI: Separate acpi_bus_trim to support two steps.

On Friday, January 11, 2013 02:40:34 PM Yinghai Lu wrote:
> Current all acpi_bus_trim callers have rmdevice to 1.
> that means it will remove all acpi devices.
> 
> When 0, is passed, it will keep the parent.
> 
> For root bus hotremove support, we need to have pci device to be
> removed before acpi devices.
> 
> So try to keep all acpi devices, and only stop drivers with them.
> 
> This change should be safe because all current callers all have 1 passed.

I'm not sure how the chanelog is related to the patch itself.

The patch modifies the behavior of acpi_bus_trim() to avoid removing all
devices (not just the start point) for rmdevice==0, which doesn't really change
the functionality, because all callers pass rmdevice=1 anyway.

Yes, we can make this change, but why is it necessary?

And why don't we remove the rmdevice argument from acpi_bus_trim() altogether?

Rafael


> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> Cc: Len Brown <lenb@...nel.org>
> Cc: linux-acpi@...r.kernel.org
> ---
>  drivers/acpi/scan.c |    5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index e380345..db7664e 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -1669,10 +1669,7 @@ int acpi_bus_trim(struct acpi_device *start, int rmdevice)
>  			child = parent;
>  			parent = parent->parent;
>  
> -			if (level == 0)
> -				err = acpi_bus_remove(child, rmdevice);
> -			else
> -				err = acpi_bus_remove(child, 1);
> +			err = acpi_bus_remove(child, rmdevice);
>  
>  			continue;
>  		}
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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