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

[Darren Hart <dvhart@infradead.org>]

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@dell.com>
> ---
> 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.

In order to make the default sane, I would suggest making the above a menu
(default n), nesting the two options below, and making WMI a default=y. This
satisfies Linus' requirement by defaulting everything to n, but enables a sane
default IFF the DELL_SMBIOS menu is enabled.

Alternatively, all of the above can be put under the "Dell Extras" menu I
proposed, and DELL_SMBIOS can default to m and DELL_SMBIOS_WMI can default to y.

>  
> +	/* register backends */
> +	wmi = init_dell_smbios_wmi();
> +	if (wmi)
> +		pr_debug("Failed to initialize WMI backend: %d\n", wmi);
> +	smm = init_dell_smbios_smm();
> +	if (smm)
> +		pr_debug("Failed to initialize SMM backend: %d\n", smm);
> +	if (wmi && smm) {
> +		pr_err("No SMBIOS backends available (wmi: %d, smm: %d)\n",
> +			wmi, smm);
> +		goto fail_sysfs;
> +	}
> +

I like the approach of building a library instead of a bunch of separate
modules.

-- 
Darren Hart
VMware Open Source Technology Center