Exemplo n.º 1
0
/*
 *	Acquire a usimple_lock.
 *
 *	MACH_RT:  Returns with preemption disabled.  Note
 *	that the hw_lock routines are responsible for
 *	maintaining preemption state.
 */
void
usimple_lock(
	usimple_lock_t	l)
{
	int i;
	unsigned int	timeouttb;				/* Used to convert time to timebase ticks */
	pc_t		pc;
#if	ETAP_LOCK_TRACE
	etap_time_t	start_wait_time;
	int		no_miss_info = 0;
#endif	/* ETAP_LOCK_TRACE */
#if	USLOCK_DEBUG
	int		count = 0;
#endif 	/* USLOCK_DEBUG */

	OBTAIN_PC(pc, l);
	USLDBG(usld_lock_pre(l, pc));
#if	ETAP_LOCK_TRACE
	ETAP_TIME_CLEAR(start_wait_time);
#endif	/* ETAP_LOCK_TRACE */

	while (!hw_lock_try(&l->interlock)) {
		ETAPCALL(if (no_miss_info++ == 0)
			start_wait_time = etap_simplelock_miss(l));
		while (hw_lock_held(&l->interlock)) {
			/*
			 *	Spin watching the lock value in cache,
			 *	without consuming external bus cycles.
			 *	On most SMP architectures, the atomic
			 *	instruction(s) used by hw_lock_try
			 *	cost much, much more than an ordinary
			 *	memory read.
			 */
#if	USLOCK_DEBUG
			if (count++ > max_lock_loops
#if	MACH_KDB && NCPUS > 1
			    && l != &kdb_lock
#endif	/* MACH_KDB && NCPUS > 1 */
			    ) {
				if (l == &printf_lock) {
					return;
				}
				mp_disable_preemption();
#if MACH_KDB
				db_printf("cpu %d looping on simple_lock(%x)"
					  "(=%x)",
					  cpu_number(), l,
					  *hw_lock_addr(l->interlock));
				db_printf(" called by %x\n", pc);
#endif
				Debugger("simple lock deadlock detection");
				count = 0;
				mp_enable_preemption();
			}
#endif 	/* USLOCK_DEBUG */
		}
	}
	ETAPCALL(etap_simplelock_hold(l, pc, start_wait_time));
	USLDBG(usld_lock_post(l, pc));
}
Exemplo n.º 2
0
/*
 *	Acquire a usimple_lock.
 *
 *	Returns with preemption disabled.  Note
 *	that the hw_lock routines are responsible for
 *	maintaining preemption state.
 */
void
usimple_lock(
	usimple_lock_t	l)
{
#ifndef	MACHINE_SIMPLE_LOCK
	DECL_PC(pc);

	OBTAIN_PC(pc, l);
	USLDBG(usld_lock_pre(l, pc));

	if(!hw_lock_to(&l->interlock, LockTimeOutTSC))	/* Try to get the lock with a timeout */ 
		panic("simple lock deadlock detection: lock=%p, cpu=%d, owning thread=0x%x", l, cpu_number(), l->interlock.lock_data);

	USLDBG(usld_lock_post(l, pc));
#else
	simple_lock((simple_lock_t)l);
#endif
}
Exemplo n.º 3
0
void
simple_lock_no_trace(
	simple_lock_t	l)
{
	pc_t		pc;

	OBTAIN_PC(pc, l);
	USLDBG(usld_lock_pre(l, pc));
	while (!hw_lock_try(&l->interlock)) {
		while (hw_lock_held(&l->interlock)) {
			/*
			 *	Spin watching the lock value in cache,
			 *	without consuming external bus cycles.
			 *	On most SMP architectures, the atomic
			 *	instruction(s) used by hw_lock_try
			 *	cost much, much more than an ordinary
			 *	memory read.
			 */
		}
	}
	USLDBG(usld_lock_post(l, pc));
}