linux-kernel - Re: [PATCH tip/locking/core] compiler-context-analysis: Support immediate acquisition after initialization

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Message-ID: <20260116152723.GE831285@noisy.programming.kicks-ass.net>
Date: Fri, 16 Jan 2026 16:27:23 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Christoph Hellwig <hch@....de>
Cc: Marco Elver <elver@...gle.com>, Steven Rostedt <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>, Will Deacon <will@...nel.org>,
	Boqun Feng <boqun.feng@...il.com>, Waiman Long <longman@...hat.com>,
	linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
	Bart Van Assche <bvanassche@....org>
Subject: Re: [PATCH tip/locking/core] compiler-context-analysis: Support
 immediate acquisition after initialization

On Fri, Jan 16, 2026 at 04:20:16PM +0100, Peter Zijlstra wrote:
> On Fri, Jan 16, 2026 at 04:10:43PM +0100, Christoph Hellwig wrote:
> > On Fri, Jan 16, 2026 at 04:07:50PM +0100, Peter Zijlstra wrote:
> > > LGTM; Steve, Christoph, does this work for you guys? Init and then lock
> > > would look something like:
> > 
> > Please do something that works without all these messy guards that just
> > obfuscate the code.
> 
> I think we're doing to have to agree to disagree on this.
> 
> Something like:
> 
> 	scoped_guard (spinlock_init, &obj->lock) {
> 		// init
> 	}
> 
> is *much* clearer than something like:
> 
> 	spinlock_init(&obj->lock);
> 	// init
> 	spinlock_deinit(&obj->lock);
> 
> Exactly because it has explicit scope. (also my deinit naming might not
> be optimal, it is ambiguous at best, probably confusing).
> 
> Not to mention that the scope things are far more robust vs error paths.

That said; you can just write:

	spin_lock_init(&obj->lock);
	__acquire_ctx_lock(&obj->lock);
	// init
	__release_ctx_lock(&obj->lock);

But I really don't see how that is 'better' in any way.