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From: Peter Zijlstra <peterz@infradead.org>
To: Heiko Carstens <hca@linux.ibm.com>
Cc: Lyude Paul <lyude@redhat.com>,
	rust-for-linux@vger.kernel.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Boqun Feng <boqun.feng@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Vasily Gorbik <gor@linux.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Sven Schnelle <svens@linux.ibm.com>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Juergen Christ <jchrist@linux.ibm.com>,
	Ilya Leoshkevich <iii@linux.ibm.com>,
	"moderated list:ARM64 PORT (AARCH64 ARCHITECTURE)"
	<linux-arm-kernel@lists.infradead.org>,
	open list <linux-kernel@vger.kernel.org>,
	"open list:S390 ARCHITECTURE" <linux-s390@vger.kernel.org>,
	"open list:GENERIC INCLUDE/ASM HEADER FILES"
	<linux-arch@vger.kernel.org>
Subject: Re: [PATCH v9 2/9] preempt: Introduce __preempt_count_{sub, add}_return()
Date: Fri, 28 Feb 2025 10:24:05 +0100	[thread overview]
Message-ID: <20250228092405.GE5880@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20250228091509.8985B18-hca@linux.ibm.com>

On Fri, Feb 28, 2025 at 10:15:09AM +0100, Heiko Carstens wrote:

> I couldn't find any cover letter for the whole patch series which describes
> what this is about, and why it is needed.
> It looks like some Rust enablement?

Yeah, more or less.

It's replacing local_irq_save() and all related functions
(spin_lock_irqsave etc..) that take a flags argument with this new thing
that frobs a recursion count in preempt_count(), obviating the need to
carry the local flags argument around.

This is nice, even for C code, less flags muck to carry around.

It would be even better if they then went and deleted all of the _irq /
_irqsave nonsense entirely.

Yes, that's going to be a big patch :-)

Also, IIRC there is some arch stuff that comes unstuck if you do this
blindly (I tried at some point, it didn't boot).


  reply	other threads:[~2025-02-28  9:26 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20250227221924.265259-1-lyude@redhat.com>
2025-02-27 22:10 ` [PATCH v9 2/9] preempt: Introduce __preempt_count_{sub, add}_return() Lyude Paul
2025-02-28  1:49   ` Boqun Feng
2025-02-28  9:15   ` Heiko Carstens
2025-02-28  9:24     ` Peter Zijlstra [this message]
2025-04-30 21:38     ` Lyude Paul
2025-05-05  9:56       ` Heiko Carstens
2025-03-01 18:49   ` kernel test robot
2025-03-01 19:00   ` kernel test robot

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