Re: [PATCH v11 0/4] Introducing a queue read/write lock implementation

[George Spelvin]

How about getting rid of that TICKET_MSB mess and doing something like:

#define TICKET_MASK	0xFFFF

static inline void ticket_spin_unlock(atomic_t *tickets)
{
	u32 t = *tickets;

	smp_mb__before_atomic_inc();

	/* Increment the low 16 bits without affecting the upper. */
	if (unlikely((~t & TICKET_MASK) == 0))
		atomic_add(-(atomic_t)TICKET_MASK, tickets);
	else
		atomic_inc(tickets);
}

That also allows up to 2^16 waiters, up from 2^15.
(Minus one on both cases, if you want to be fussy.)
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