RE: [PATCH v2] apei/ghes: correctly return NULL for ghes_get_devices()

[Justin He]

Hi Li,

> -----Original Message-----
> From: Li Yang <leoyang.li@xxxxxxx>
> Sent: Saturday, May 20, 2023 4:13 AM
> To: Rafael J. Wysocki <rafael@xxxxxxxxxx>; Len Brown <lenb@xxxxxxxxxx>;
> James Morse <James.Morse@xxxxxxx>; Tony Luck <tony.luck@xxxxxxxxx>;
> Borislav Petkov <bp@xxxxxxxxx>; Justin He <Justin.He@xxxxxxx>
> Cc: Li Yang <leoyang.li@xxxxxxx>; linux-acpi@xxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: [PATCH v2] apei/ghes: correctly return NULL for ghes_get_devices()
>
> Since 315bada690e0 ("EDAC: Check for GHES preference in the chipset-specific
> EDAC drivers"), vendor specific EDAC driver will not probe correctly when
> CONFIG_ACPI_APEI_GHES is enabled but no GHES device is present.  Make
> ghes_get_devices() return NULL when the GHES device list is empty to fix the
> problem.
>
> Fixes: 9057a3f7ac36 ("EDAC/ghes: Prepare to make ghes_edac a proper
> module")
> Signed-off-by: Li Yang <leoyang.li@xxxxxxx>
> Cc: Jia He <justin.he@xxxxxxx>
> ---
>
> V2: fix the fallthrough case in x86 path
>
>  drivers/acpi/apei/ghes.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c index
> 34ad071a64e9..4382fe13ee3e 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -1544,6 +1544,8 @@ struct list_head *ghes_get_devices(void)
>
>                       pr_warn_once("Force-loading ghes_edac on an unsupported
> platform. You're on your own!\n");
>               }
> +     } else if (list_empty(&ghes_devs)) {
> +             return NULL;
>       }
I have no major objections to the fix. Just curious about the edac driver in you platform.
IIUC, in your case, CONFIG_ACPI_APEI_GHES is enabled and edac_ghes driver is either not
loaded or fails to load. Is my understanding correct?
I wonder whether ghes_get_devices() can unblock such check condition and let other
chipset-specific edac drivers continue with the initialization. @Toshi, What do u think of it?


--
Cheers,
Justin (Jia He)


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