linux-kernel - Re: [Bug fix PATCH] ACPI,acpi_memhotplug: enable acpi_memory_info->enabled of memory device presented at boot-time

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Date:	Wed, 13 Mar 2013 08:50:13 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Cc:	rjw@...k.pl, linux-acpi@...r.kernel.org, tangchen@...fujitsu.com,
	wency@...fujitsu.com, laijs@...fujitsu.com,
	linux-kernel@...r.kernel.org
Subject: Re: [Bug fix PATCH] ACPI,acpi_memhotplug: enable
 acpi_memory_info->enabled of memory device presented at boot-time

On Wed, 2013-03-13 at 15:54 +0900, Yasuaki Ishimatsu wrote:
> At http://marc.info/?l=linux-acpi&m=135769405622667&w=2 thread,
> Toshi Kani mentioned as follows:
> 
> "I have a question about the change you made in commit 65479472 in
> acpi_memhotplug.c.  This change seems to require that
> acpi_memory_enable_device() calls add_memory() to add all memory ranges
> represented by memory device objects at boot-time, and keep the results
> be used for hot-remove.  
> 
> If I understand it right, this add_memory() call fails with EEXIST at
> boot-time since all memory ranges should have been added from EFI memory
> table (or e820) already.  This results all memory ranges be marked as !
> enabled & !failed.  I think this means that we cannot hot-delete any
> memory ranges presented at boot-time since acpi_memory_remove_memory()
> only calls remove_memory() when the enabled flag is set.  Is that
> correct?"
> 
> Above mention is correct. Thus even if memory device supports hotplug,
> memory presented at boot-time cannot be hot removed since the memory
> device's acpi_memory_info->enabled is always 0.
> 
> This patch changes to set 1 to "acpi_memory_info->enabled" of memory
> device presented at boot-time for hot removing the memory device.
> 
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
> 
> ---
>  drivers/acpi/acpi_memhotplug.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
> index da1f82b..88fd46a 100644
> --- a/drivers/acpi/acpi_memhotplug.c
> +++ b/drivers/acpi/acpi_memhotplug.c
> @@ -254,8 +254,8 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
>  			continue;
>  		}
>  
> -		if (!result)
> -			info->enabled = 1;
> +		info->enabled = 1;

Do we still need to keep the enable bit?  I think !failed means enabled
with this change.

Thanks,
-Toshi


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