linux-kernel - Re: [PATCH] x86/microcode: move @microcode

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Message-ID: <20230324151933.GCZB2/hUOFuECIF1AG@fat_crate.local>
Date:   Fri, 24 Mar 2023 16:19:33 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     John Ogness <john.ogness@...utronix.de>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/microcode: move @microcode_mutex definition near
 usage

On Fri, Mar 24, 2023 at 02:17:10PM +0106, John Ogness wrote:
> I was doing some tests with CONFIG_PREEMPT_RT. I did not think that
> mattered, since the mutex is obviously defined but not used for
> !CONFIG_MICROCODE_LATE_LOADING.

Oh sure, I see that. I'd still like to have in the commit message why
exactly it happens.

> Digging deeper I see that initializing @wait_list in
> __MUTEX_INITIALIZER() is what is allowing unused global mutexes to go
> unnoticed. Since with CONFIG_PREEMPT_RT the mutex is different and
> initialized differently, it is (correctly) detected as unused.
> 
> CONFIG_PREEMPT_RT cannot be enabled yet, so this patch is not urgent for
> mainline. But at some point it will need fixing.

Sure, send it to me when it can be triggered with a .config with the
upstream tree, along with exact explanation how it happens and I'll
queue it.

Thx.

-- 
Regards/Gruss,
    Boris.

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