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

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Message-ID: <20260121202427.099c36ab@gandalf.local.home>
Date: Wed, 21 Jan 2026 20:24:27 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Christoph Hellwig <hch@....de>, Marco Elver <elver@...gle.com>, 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, 16 Jan 2026 16:47:54 +0100
Peter Zijlstra <peterz@...radead.org> wrote:

> struct obj {
> 	spinlock_t	lock;
> 	int		state __guarded_by(lock);
> };
> 
> struct obj *create_obj(void)
> {
> 	struct obj *obj = kzmalloc(sizeof(*obj), GFP_KERNEL);
> 	if (!obj)
> 		return NULL;
> 
> 	spin_lock_init(&obj->lock);
> 	obj->state = INIT_STATE; // error: ->state demands ->lock is held
> }

I haven't seen all the other approaches, but would a macro be able to hide
it with some kind of obfuscation from the compiler?


	GUARD_INIT(obj->state, INIT_STATE);

which would be something like a WRITE_ONCE() macro. I'm not sure what
tooling there is to disable checks for a small bit of code like this.

-- Steve