linux-kernel - Re: [PATCH] x86/MCE/AMD: Decrement threshold_bank refcount when removing threshold blocks

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Message-ID: <Y1l8nx1KnTFP1xKj@zn.tnic>
Date:   Wed, 26 Oct 2022 20:29:51 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Yazen Ghannam <yazen.ghannam@....com>
Cc:     Greg KH <gregkh@...uxfoundation.org>, linux-edac@...r.kernel.org,
        linux-kernel@...r.kernel.org, tony.luck@...el.com, x86@...nel.org,
        Smita.KoralahalliChannabasappa@....com, mpatocka@...hat.com
Subject: Re: [PATCH] x86/MCE/AMD: Decrement threshold_bank refcount when
 removing threshold blocks

On Wed, Oct 26, 2022 at 03:39:15PM +0000, Yazen Ghannam wrote:
> What's the issue with my original patch?

Do you see it?

> @@ -1258,10 +1258,10 @@ static void __threshold_remove_blocks(struct threshold_bank *b)
>         struct threshold_block *pos = NULL;
>         struct threshold_block *tmp = NULL;
>  
> -       kobject_del(b->kobj);
> +       kobject_put(b->kobj);
>  
>         list_for_each_entry_safe(pos, tmp, &b->blocks->miscj, miscj)
> -               kobject_del(&pos->kobj);
> +               kobject_put(b->kobj);

You're basically putting the parent as many times as there are elements
on the ->miscj list.

Basically what Greg doesn't like.

Him and I need to talk it over first whether my gross hack of grafting
the bank4 kobject hierarchy from CPU0 onto the other CPUs on the node is
even viable so stay tuned...

> I think this is the simplest way to fix the current implementation.
> But we should probably get rid of this kobject sharing idea in light
> of Greg's comments.

You said it. :)

Or maybe do a better one.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette