EDAC, ghes: Do not register instance if platform is not whitelisted

[Toshi Kani <toshi.kani@hpe.com>]

On Mon, 2018-04-23 at 14:27 +0200, Borislav Petkov wrote:
> Lemme write an official patch:
> 
> ---
> Tony reported seeing
> 
>   "Internal error: Can't find EDAC structure"
> 
> when injecting correctable errors.
> 
> The problem is that we should exit registration when platform doesn't
> match the whitelisted ones.
> 
> Do that.
> 
> Reviewed-by: Tony Luck <tony.luck@intel.com>
> Signed-off-by: Borislav Petkov <bp@suse.de>
> Cc: Toshi Kani <toshi.kani@hpe.com>
> Fixes: 5deed6b6a479 ("EDAC, ghes: Add platform check")
> Link: https://lkml.kernel.org/r/20180420182015.zao3olss4tvvlxki@agluck-desk
> ---
>  drivers/edac/ghes_edac.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c
> index 68b6ee18bea6..4a9231993699 100644
> --- a/drivers/edac/ghes_edac.c
> +++ b/drivers/edac/ghes_edac.c
> @@ -439,7 +439,7 @@ int ghes_edac_register(struct ghes *ghes, struct device *dev)
>  	/* Check if safe to enable on this system */
>  	idx = acpi_match_platform_list(plat_list);
>  	if (!force_load && idx < 0)
> -		return 0;
> +		return -ENODEV;
>  

Umm..., I do not think this change is correct.  This causes an error to
ghes_probe(), which disables GHES itself.  ghes and ghes_edac are
separate modules.  That is, ghes_edac works on top of ghes as an
optional module.

I think the right fix is to simply remove the error message.  This will
make it consistent with the case of CONFIG_EDAC_GHES disabled.  Please
see include/acpi/ghes.h.

Thanks,
-Toshi