Re: [PATCH] EDAC/amd64: Fix possible module load failure on some UMC usage combinations

[Naik, Avadhut]

On 12/10/2024 03:55, Borislav Petkov wrote:
> On Mon, Dec 09, 2024 at 09:55:10PM +0000, Avadhut Naik wrote:
>> Starting Zen4, AMD SOCs have 12 Unified Memory Controllers (UMCs) per
>> socket.
>>
>> When the amd64_edac module is being loaded, these UMCs are traversed to
>> determine if they have SdpInit (SdpCtrl[31]) and EccEnabled (UmcCapHi[30])
>> bits set and create masks in umc_en_mask and ecc_en_mask respectively.
>>
>> However, the current data type of these variables is u8. As a result, if
>> only the last 4 UMCs (UMC8 - UMC11) of the system have been utilized,
>> umc_ecc_enabled() will return false. Consequently, the module may fail to
>> load on these systems.
>>
>> Change the data type of these variables to u16.
> 
> No need to explain what the patch does. The "why" is enough.
>  
Will remove this line.

>> Signed-off-by: Avadhut Naik <avadhut.naik@xxxxxxx>
>> ---
>>  drivers/edac/amd64_edac.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> This looks like it needs a CC:stable and a Fixes: tag, right?
> 
It does need a Fixes: tag. Will add that.
But not so sure about the CC:stable.
Quoting from stable-kernel-rules about the patches that are accepted into stable.

It must fix a real bug that bothers people (not a, “This could be a problem...” type thing).

This has not been reported by anyone yet. IMO, it classifies as
"This could be a problem" type issue.
Would you agree?

> While at it, you can simply make those vars int and be done with it.
> 
Okay, will change the data type of these 2 variables to int.
> Thx.
> 

-- 
Thanks,
Avadhut Naik