Re: [PATCH v3 3/3] platform/x86: dell-smbios: Link all dell-smbios-* modules together

[Darren Hart]

On Tue, Feb 27, 2018 at 12:23:04PM -0600, Mario Limonciello wrote:
> Some race conditions were raised due to dell-smbios and its backends
> not being ready by the time that a consumer would call one of the
> exported methods.
> 
> To avoid this problem, guarantee that all initialization has been
> done by linking them all together and running init for them all.
> 
> As part of this change the Kconfig needs to be adjusted so that
> CONFIG_DELL_SMBIOS_SMM and CONFIG_DELL_SMBIOS_WMI are boolean
> rather than modules.
> 
> CONFIG_DELL_SMBIOS is a visually selectable option again and both
> CONFIG_DELL_SMBIOS_WMI and CONFIG_DELL_SMBIOS_SMM are optional.
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxxx>
> ---
> Changes from v2:
>  * Move rest of #ifdef out of source files
>  * Only compile units as necessary
> 
>  drivers/platform/x86/Kconfig            | 11 ++++++++---
>  drivers/platform/x86/Makefile           |  4 ++--
>  drivers/platform/x86/dell-smbios-base.c | 21 ++++++++++++++++++++-
>  drivers/platform/x86/dell-smbios-smm.c  | 18 ++++--------------
>  drivers/platform/x86/dell-smbios-wmi.c  | 14 ++++----------
>  drivers/platform/x86/dell-smbios.h      | 27 ++++++++++++++++++++++++++-
>  6 files changed, 64 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index 9a8f964..0c0897e 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -106,10 +106,15 @@ config ASUS_LAPTOP
>  	  If you have an ACPI-compatible ASUS laptop, say Y or M here.
>  
>  config DELL_SMBIOS
> -	tristate
> +	tristate "Dell SMBIOS driver"
> +	---help---
> +	This provides support for the Dell SMBIOS calling interface.
> +	If you have a Dell computer you should enable this option.
> +
> +	Be sure to select at least one backend for it to work properly.
>  
>  config DELL_SMBIOS_WMI
> -	tristate "Dell SMBIOS calling interface (WMI implementation)"
> +	bool "Dell SMBIOS driver WMI support"
>  	depends on ACPI_WMI
>  	select DELL_WMI_DESCRIPTOR
>  	select DELL_SMBIOS

Blarg, this also violates the kconfig-language guidance for using select
only for non-visible symbols with no dependencies.

I have a patch that works, but I don't love it. We can remove the prompt
from DELL_SMBIOS, and make DELL_SMBIOS_WMI|SMM "depend on" DELL_SMBIOS.
The options just appear sort of randomly when either DELL_LAPTOP or
DELL_WMI are selected - but they can default to y, which is nice.

I have a subsequent patch which makes DELL_SMBIOS_WMI|SMM "depend on"
DELL_LAPTOP, which makes this look a lot nicer. These just appear under
DELL_LAPTOP as bool options. The problem with this approach is DELL_WMI
also requires DELL_SMBIOS and DELL_WMI doesn't currently depend on
DELL_LAPTOP. One option is to make it depend on DELL_LAPTOP as it seems
unlikely for them to ever be used separately.  I don't love this either.
Thoughts?

Perhaps the compromise is leave the DELL_SMBIOS prompt. This doesn't
have the negative consequences the kconfig-languages is trying to guard
against, and it makes it obvious what the DELL_SMBIOS_* options are -
and we can still default them to y. See below.

This seems like it might be the least bad option at the moment. I'll
keep thinking on it a bit...

From: "Darren Hart (VMware)" <dvhart@xxxxxxxxxxxxx>
Date: Fri, 2 Mar 2018 17:40:32 -0800
Subject: [PATCH] platform/x86: Allow for SMBIOS backend defaults

Avoid accidental configurations by setting default y for DELL_SMBIOS
backends. Avoid this impacting the default build size, by making them
dependent on DELL_SMBIOS, so they only appear when DELL_SMBIOS is
manually selected, or by DELL_LAPTOP or DELL_WMI.

Signed-off-by: Darren Hart (VMware) <dvhart@xxxxxxxxxxxxx>
---
 drivers/platform/x86/Kconfig | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index e3f682c..022c837 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -115,9 +115,10 @@ config DELL_SMBIOS
 
 config DELL_SMBIOS_WMI
 	bool "Dell SMBIOS driver WMI backend"
+	default y
 	depends on ACPI_WMI
 	select DELL_WMI_DESCRIPTOR
-	select DELL_SMBIOS
+	depends on DELL_SMBIOS
 	---help---
 	This provides an implementation for the Dell SMBIOS calling interface
 	communicated over ACPI-WMI.
@@ -128,8 +129,9 @@ config DELL_SMBIOS_WMI
 
 config DELL_SMBIOS_SMM
 	bool "Dell SMBIOS driver SMM backend"
+	default y
 	depends on DCDBAS
-	select DELL_SMBIOS
+	depends on DELL_SMBIOS
 	---help---
 	This provides an implementation for the Dell SMBIOS calling interface
 	communicated over SMI/SMM.
-- 
2.9.5


-- 
Darren Hart
VMware Open Source Technology Center