Re: [PATCH v2] locking: SIX locks (shared/intent/exclusive)

[Kent Overstreet]

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Thanks - I think I'll just delete that comment, it's out of date and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 :)