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From: Thomas Gleixner <tglx@kernel.org>
To: Boqun Feng <boqun@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>, linux-kernel@vger.kernel.org,
 linux-tip-commits@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH] locking: Revert switching guards to
 _irq_{disable,enable}()
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Date: Mon, 31 Aug 2026 12:02:50 +0200
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On Sun, Aug 30 2026 at 14:23, Boqun Feng wrote:
> On Sun, Aug 30, 2026 at 09:57:30PM +0200, Thomas Gleixner wrote:
>> The actual PREEMPT_COUNT_IRQFLAGS thing will be 7.4 material obviously
>> and as this is confined to Rust then it's trivial enough to work around
>> it locally without exposing more stuff. See tiny delta patch below.
>> 
>> So the only side effect of that is that the Rust implementation will not
>> be fully integrated into the preempt count magic, but it should just
>> work, no?
>> 
>
> Right, that works. It's similar to the "alternatively" approach I
> mentioned here [1].

But thinking more about it. It actually just works with the preempt
count bits independent of PREEMPT_COUNT_IRQFLAGS.

For PREEMPT_COUNT_IRQFLAGS=n, Rust is the only one using it.

For PREEMPT_COUNT_IRQFLAGS=y, the Rust part integrates with the core
implementation. And once all Rust supporting architectures are enabling
PREEMPT_COUNT_IRQFLAGS the Rust extra magic goes away.

No?

Thanks,

        tglx