Re: [PATCH v4 next 3/9] locking/osq_lock: Set prev_cpu=0 instead of locked=1

[Peter Zijlstra]

On Tue, Sep 15, 2026 at 03:13:15PM +0200, Peter Zijlstra wrote:
> On Mon, Sep 07, 2026 at 09:41:27AM +0100, David Laight wrote:
> 
> > +	/*
> > +	 * If 'prev' tries to remove itself from the list before we write
> > +	 * a new value to prev->next it will spin in osq_wait_next().
> > +	 */
> 
> This comment pertains to what? 
> 
> > +	/* Invalidate prev_cpu matching osq_unlock() */
> > +	node->prev = 0;
> 
> I'm confused, osq_unlock() does no such thing.

The next patch adds a comment stating that this store is not strictly
needed. And only serves to ensure node->prev ends up being 0 in all
paths.

That comment *should* obviously have been here. Also, I would *much*
rather have this store at the top, next to node->next = NULL; That is
much saner.