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From:   Kent Overstreet <kent.overstreet@linux.dev>
To:     Boqun Feng <boqun.feng@gmail.com>
Cc:     linux-kernel@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
        Waiman Long <longman@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Brian Foster <bfoster@redhat.com>,
        Dave Chinner <dchinner@redhat.com>
Subject: Re: [PATCH v2] locking: SIX locks (shared/intent/exclusive)
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References: <20230522171314.1953699-1-kent.overstreet@linux.dev>
 <ZGvnJZYQfAmgdsqr@boqun-archlinux>
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On Mon, May 22, 2023 at 03:05:25PM -0700, Boqun Feng wrote:
> > + * bits 29-30		has read waiters
> > + * bits 30-31		has intent waiters
> > + * bits 31-32		has write waiters
> > + */
> > +
> > +#define SIX_LOCK_HELD_read_OFFSET	0
> > +#define SIX_LOCK_HELD_read		~(~0U << 26)
> > +#define SIX_LOCK_HELD_intent		(1U << 26)
> > +#define SIX_LOCK_HELD_write		(1U << 27)
> > +#define SIX_LOCK_WAITING_read		(1U << (28 + SIX_LOCK_read))
> > +#define SIX_LOCK_WAITING_intent		(1U << (28 + SIX_LOCK_intent))
> > +#define SIX_LOCK_WAITING_write		(1U << (28 + SIX_LOCK_write))
> > +#define SIX_LOCK_NOSPIN			(1U << 31)
> 
> ^ NOSPIN is the 31st bit.

Thanks - I think I'll just delete that comment, it's out of date and
the state bits have simplified a bit :)