Pull ticket-spinaphore into release branch

 * this primitive it can be moved up to a spinaphore.h header.

 */

struct spinaphore {

	atomic_t	cur;

	unsigned long	ticket;

	unsigned long	serve;

};

static inline void spinaphore_init(struct spinaphore *ss, int val)

{

	atomic_set(&ss->cur, val);

	ss->ticket = 0;

	ss->serve = val;

}

static inline void down_spin(struct spinaphore *ss)

{

	while (unlikely(!atomic_add_unless(&ss->cur, -1, 0)))

		while (atomic_read(&ss->cur) == 0)

	unsigned long t = ia64_fetchadd(1, &ss->ticket, acq), serve;

	if (time_before(t, ss->serve))

		return;

	ia64_invala();

	for (;;) {

		asm volatile ("ld4.c.nc %0=[%1]" : "=r"(serve) : "r"(&ss->serve) : "memory");

		if (time_before(t, serve))

			return;

		cpu_relax();

	}

}

static inline void up_spin(struct spinaphore *ss)

{

	atomic_add(1, &ss->cur);

	ia64_fetchadd(1, &ss->serve, rel);

}

static struct spinaphore ptcg_sem;