Beispiel #1
0
static void 
clock_track_calend_nowait(void)
{
	int i;

	for (i = 0; i < 2; i++) {
		struct clock_calend tmp = clock_calend;

		/*
		 * Set the low bit if the generation count; since we use a
		 * barrier instruction to do this, we are guaranteed that this
		 * will flag an update in progress to an async caller trying
		 * to examine the contents.
		 */
		(void)hw_atomic_or(&flipflop[i].gen, 1);

		flipflop[i].calend = tmp;

		/*
		 * Increment the generation count to clear the low bit to
		 * signal completion.  If a caller compares the generation
		 * count after taking a copy while in progress, the count
		 * will be off by two.
		 */
		(void)hw_atomic_add(&flipflop[i].gen, 1);
	}
}
/*
 * uio_create - create an uio_t.
 * 	Space is allocated to hold up to a_iovcount number of iovecs.  The uio_t
 *	is not fully initialized until all iovecs are added using uio_addiov calls.
 *	a_iovcount is the maximum number of iovecs you may add.
 */
uio_t uio_create( int a_iovcount,		/* number of iovecs */
				  off_t a_offset,		/* current offset */
				  int a_spacetype,		/* type of address space */
				  int a_iodirection )	/* read or write flag */
{
	void *				my_buf_p;
	int					my_size;
	uio_t				my_uio;
	
	my_size = UIO_SIZEOF(a_iovcount);
	my_buf_p = kalloc(my_size);
	my_uio = uio_createwithbuffer( a_iovcount, 
									 a_offset,
									 a_spacetype,
									 a_iodirection,
									 my_buf_p,
									 my_size );
	if (my_uio != 0) {
		/* leave a note that we allocated this uio_t */
		my_uio->uio_flags |= UIO_FLAGS_WE_ALLOCED;
#if DEBUG
		(void)hw_atomic_add(&uio_t_count, 1);
#endif
	}
	
	return( my_uio );
}
Beispiel #3
0
/*
 *	processor_up:
 *
 *	Flag processor as up and running, and available
 *	for scheduling.
 */
void
processor_up(
	processor_t			processor)
{
	processor_set_t		pset;
	spl_t				s;

	s = splsched();
	init_ast_check(processor);
	pset = processor->processor_set;
	pset_lock(pset);
	++pset->online_processor_count;
	enqueue_tail(&pset->active_queue, (queue_entry_t)processor);
	processor->state = PROCESSOR_RUNNING;
	(void)hw_atomic_add(&processor_avail_count, 1);
	commpage_update_active_cpus();
	pset_unlock(pset);
	ml_cpu_up();
	splx(s);

#if CONFIG_DTRACE
	if (dtrace_cpu_state_changed_hook)
		(*dtrace_cpu_state_changed_hook)(processor->cpu_id, TRUE);
#endif
}
Beispiel #4
0
void
OSMalloc_Tagref(
	 OSMallocTag		tag)
{
	if (!((tag->OSMT_state & OSMT_VALID_MASK) == OSMT_VALID)) 
		panic("OSMalloc_Tagref():'%s' has bad state 0x%08X\n", tag->OSMT_name, tag->OSMT_state);

	(void)hw_atomic_add(&tag->OSMT_refcnt, 1);
}
Beispiel #5
0
void
vnode_pager_reference(
	memory_object_t		mem_obj)
{	
	register vnode_pager_t	vnode_object;
	unsigned int		new_ref_count;

	vnode_object = vnode_pager_lookup(mem_obj);
	new_ref_count = hw_atomic_add(&vnode_object->ref_count, 1);
	assert(new_ref_count > 1);
}
Beispiel #6
0
/*
 * uio_duplicate - allocate a new uio and make a copy of the given uio_t.
 *	may return NULL.
 */
uio_t uio_duplicate( uio_t a_uio )
{
	uio_t		my_uio;
	int			i;

	if (a_uio == NULL) {
		return(NULL);
	}
	
	my_uio = (uio_t) kalloc(a_uio->uio_size);
	if (my_uio == 0) {
		panic("%s :%d - allocation failed\n", __FILE__, __LINE__); 
	}
	
	bcopy((void *)a_uio, (void *)my_uio, a_uio->uio_size);
	/* need to set our iovec pointer to point to first active iovec */
	if (my_uio->uio_max_iovs > 0) {
		my_uio->uio_iovs.uiovp = (struct user_iovec *)
			(((uint8_t *)my_uio) + sizeof(struct uio));

		/* advance to first nonzero iovec */
		if (my_uio->uio_iovcnt > 0) {
			for ( i = 0; i < my_uio->uio_max_iovs; i++ ) {
				if (UIO_IS_USER_SPACE(a_uio)) {
					if (my_uio->uio_iovs.uiovp->iov_len != 0) {
						break;
					}
					my_uio->uio_iovs.uiovp++;
				}
				else {
					if (my_uio->uio_iovs.kiovp->iov_len != 0) {
						break;
					}
					my_uio->uio_iovs.kiovp++;
				}
			}
		}
	}

	my_uio->uio_flags = UIO_FLAGS_WE_ALLOCED | UIO_FLAGS_INITED;
#if DEBUG
		(void)hw_atomic_add(&uio_t_count, 1);
#endif


	return(my_uio);
}
Beispiel #7
0
void
lck_grp_lckcnt_incr(
	lck_grp_t	*grp,
	lck_type_t	lck_type)
{
	unsigned int	*lckcnt;

	switch (lck_type) {
	case LCK_TYPE_SPIN:
		lckcnt = &grp->lck_grp_spincnt;
		break;
	case LCK_TYPE_MTX:
		lckcnt = &grp->lck_grp_mtxcnt;
		break;
	case LCK_TYPE_RW:
		lckcnt = &grp->lck_grp_rwcnt;
		break;
	default:
		return panic("lck_grp_lckcnt_incr(): invalid lock type: %d\n", lck_type);
	}

	(void)hw_atomic_add(lckcnt, 1);
}
Beispiel #8
0
/*
 * Create a new thread.
 * Doesn't start the thread running.
 */
static kern_return_t
thread_create_internal(
	task_t					parent_task,
	integer_t				priority,
	thread_continue_t		continuation,
	int						options,
#define TH_OPTION_NONE		0x00
#define TH_OPTION_NOCRED	0x01
#define TH_OPTION_NOSUSP	0x02
	thread_t				*out_thread)
{
	thread_t				new_thread;
	static thread_t			first_thread = THREAD_NULL;

	/*
	 *	Allocate a thread and initialize static fields
	 */
	if (first_thread == THREAD_NULL)
		new_thread = first_thread = current_thread();
	new_thread = (thread_t)zalloc(thread_zone);
	if (new_thread == THREAD_NULL)
		return (KERN_RESOURCE_SHORTAGE);

	if (new_thread != first_thread)
		*new_thread = thread_template;

#ifdef MACH_BSD
	new_thread->uthread = uthread_alloc(parent_task, new_thread, (options & TH_OPTION_NOCRED) != 0);
	if (new_thread->uthread == NULL) {
		zfree(thread_zone, new_thread);
		return (KERN_RESOURCE_SHORTAGE);
	}
#endif  /* MACH_BSD */

	if (machine_thread_create(new_thread, parent_task) != KERN_SUCCESS) {
#ifdef MACH_BSD
		void *ut = new_thread->uthread;

		new_thread->uthread = NULL;
		/* cred free may not be necessary */
		uthread_cleanup(parent_task, ut, parent_task->bsd_info);
		uthread_cred_free(ut);
		uthread_zone_free(ut);
#endif  /* MACH_BSD */

		zfree(thread_zone, new_thread);
		return (KERN_FAILURE);
	}

	new_thread->task = parent_task;

	thread_lock_init(new_thread);
	wake_lock_init(new_thread);

	lck_mtx_init(&new_thread->mutex, &thread_lck_grp, &thread_lck_attr);

	ipc_thread_init(new_thread);
	queue_init(&new_thread->held_ulocks);

	new_thread->continuation = continuation;

	lck_mtx_lock(&tasks_threads_lock);
	task_lock(parent_task);

	if (	!parent_task->active || parent_task->halting ||
			((options & TH_OPTION_NOSUSP) != 0 &&
			 	parent_task->suspend_count > 0)	||
			(parent_task->thread_count >= task_threadmax &&
				parent_task != kernel_task)		) {
		task_unlock(parent_task);
		lck_mtx_unlock(&tasks_threads_lock);

#ifdef MACH_BSD
		{
			void *ut = new_thread->uthread;

			new_thread->uthread = NULL;
			uthread_cleanup(parent_task, ut, parent_task->bsd_info);
			/* cred free may not be necessary */
			uthread_cred_free(ut);
			uthread_zone_free(ut);
		}
#endif  /* MACH_BSD */
		ipc_thread_disable(new_thread);
		ipc_thread_terminate(new_thread);
		lck_mtx_destroy(&new_thread->mutex, &thread_lck_grp);
		machine_thread_destroy(new_thread);
		zfree(thread_zone, new_thread);
		return (KERN_FAILURE);
	}

	/* New threads inherit any default state on the task */
	machine_thread_inherit_taskwide(new_thread, parent_task);

	task_reference_internal(parent_task);

	if (new_thread->task->rusage_cpu_flags & TASK_RUSECPU_FLAGS_PERTHR_LIMIT) {
		/*
		 * This task has a per-thread CPU limit; make sure this new thread
		 * gets its limit set too, before it gets out of the kernel.
		 */
		set_astledger(new_thread);
	}
	new_thread->t_threadledger = LEDGER_NULL;	/* per thread ledger is not inherited */
	new_thread->t_ledger = new_thread->task->ledger;
	if (new_thread->t_ledger)
		ledger_reference(new_thread->t_ledger);

	/* Cache the task's map */
	new_thread->map = parent_task->map;

	/* Chain the thread onto the task's list */
	queue_enter(&parent_task->threads, new_thread, thread_t, task_threads);
	parent_task->thread_count++;
	
	/* So terminating threads don't need to take the task lock to decrement */
	hw_atomic_add(&parent_task->active_thread_count, 1);

	/* Protected by the tasks_threads_lock */
	new_thread->thread_id = ++thread_unique_id;

	queue_enter(&threads, new_thread, thread_t, threads);
	threads_count++;

	timer_call_setup(&new_thread->wait_timer, thread_timer_expire, new_thread);
	timer_call_setup(&new_thread->depress_timer, thread_depress_expire, new_thread);

#if CONFIG_COUNTERS
	/*
	 * If parent task has any reservations, they need to be propagated to this
	 * thread.
	 */
	new_thread->t_chud = (TASK_PMC_FLAG == (parent_task->t_chud & TASK_PMC_FLAG)) ? 
		THREAD_PMC_FLAG : 0U;
#endif

	/* Set the thread's scheduling parameters */
	new_thread->sched_mode = SCHED(initial_thread_sched_mode)(parent_task);
	new_thread->sched_flags = 0;
	new_thread->max_priority = parent_task->max_priority;
	new_thread->task_priority = parent_task->priority;
	new_thread->priority = (priority < 0)? parent_task->priority: priority;
	if (new_thread->priority > new_thread->max_priority)
		new_thread->priority = new_thread->max_priority;
#if CONFIG_EMBEDDED 
	if (new_thread->priority < MAXPRI_THROTTLE) {
		new_thread->priority = MAXPRI_THROTTLE;
	}
#endif /* CONFIG_EMBEDDED */
	new_thread->importance =
					new_thread->priority - new_thread->task_priority;
#if CONFIG_EMBEDDED
	new_thread->saved_importance = new_thread->importance;
	/* apple ios daemon starts all threads in darwin background */
	if (parent_task->ext_appliedstate.apptype == PROC_POLICY_IOS_APPLE_DAEMON) {
		/* Cannot use generic routines here so apply darwin bacground directly */
		new_thread->policystate.hw_bg = TASK_POLICY_BACKGROUND_ATTRIBUTE_ALL;
		/* set thread self backgrounding */
		new_thread->appliedstate.hw_bg = new_thread->policystate.hw_bg;
		/* priority will get recomputed suitably bit later */
		new_thread->importance = INT_MIN;
		/* to avoid changes to many pri compute routines, set the effect of those here */
		new_thread->priority = MAXPRI_THROTTLE;
	}
#endif /* CONFIG_EMBEDDED */

#if defined(CONFIG_SCHED_TRADITIONAL)
	new_thread->sched_stamp = sched_tick;
	new_thread->pri_shift = sched_pri_shift;
#endif
	SCHED(compute_priority)(new_thread, FALSE);

	new_thread->active = TRUE;

	*out_thread = new_thread;

	{
		long	dbg_arg1, dbg_arg2, dbg_arg3, dbg_arg4;

		kdbg_trace_data(parent_task->bsd_info, &dbg_arg2);

		KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE, 
			TRACEDBG_CODE(DBG_TRACE_DATA, 1) | DBG_FUNC_NONE,
			(vm_address_t)(uintptr_t)thread_tid(new_thread), dbg_arg2, 0, 0, 0);

		kdbg_trace_string(parent_task->bsd_info,
							&dbg_arg1, &dbg_arg2, &dbg_arg3, &dbg_arg4);

		KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE, 
			TRACEDBG_CODE(DBG_TRACE_STRING, 1) | DBG_FUNC_NONE,
			dbg_arg1, dbg_arg2, dbg_arg3, dbg_arg4, 0);
	}

	DTRACE_PROC1(lwp__create, thread_t, *out_thread);

	return (KERN_SUCCESS);
}
Beispiel #9
0
/*
 * Create a new thread.
 * Doesn't start the thread running.
 */
static kern_return_t
thread_create_internal(
	task_t					parent_task,
	integer_t				priority,
	thread_continue_t		continuation,
	thread_t				*out_thread)
{
	thread_t				new_thread;
	static thread_t			first_thread;

	/*
	 *	Allocate a thread and initialize static fields
	 */
	if (first_thread == NULL)
		new_thread = first_thread = current_thread();
	else
		new_thread = (thread_t)zalloc(thread_zone);
	if (new_thread == NULL)
		return (KERN_RESOURCE_SHORTAGE);

	if (new_thread != first_thread)
		*new_thread = thread_template;

#ifdef MACH_BSD
    {
		new_thread->uthread = uthread_alloc(parent_task, new_thread);
		if (new_thread->uthread == NULL) {
			zfree(thread_zone, new_thread);
			return (KERN_RESOURCE_SHORTAGE);
		}
	}
#endif  /* MACH_BSD */

	if (machine_thread_create(new_thread, parent_task) != KERN_SUCCESS) {
#ifdef MACH_BSD
		{
			void *ut = new_thread->uthread;

			new_thread->uthread = NULL;
			/* cred free may not be necessary */
			uthread_cleanup(parent_task, ut, parent_task->bsd_info);
			uthread_cred_free(ut);
			uthread_zone_free(ut);
		}
#endif  /* MACH_BSD */
		zfree(thread_zone, new_thread);
		return (KERN_FAILURE);
	}

    new_thread->task = parent_task;

	thread_lock_init(new_thread);
	wake_lock_init(new_thread);

	mutex_init(&new_thread->mutex, 0);

	ipc_thread_init(new_thread);
	queue_init(&new_thread->held_ulocks);

	new_thread->continuation = continuation;

	mutex_lock(&tasks_threads_lock);
	task_lock(parent_task);

	if (	!parent_task->active							||
			(parent_task->thread_count >= THREAD_MAX	&&
			 parent_task != kernel_task)) {
		task_unlock(parent_task);
		mutex_unlock(&tasks_threads_lock);

#ifdef MACH_BSD
		{
			void *ut = new_thread->uthread;

			new_thread->uthread = NULL;
			uthread_cleanup(parent_task, ut, parent_task->bsd_info);
			/* cred free may not be necessary */
			uthread_cred_free(ut);
			uthread_zone_free(ut);
		}
#endif  /* MACH_BSD */
		ipc_thread_disable(new_thread);
		ipc_thread_terminate(new_thread);
		machine_thread_destroy(new_thread);
		zfree(thread_zone, new_thread);
		return (KERN_FAILURE);
	}

	task_reference_internal(parent_task);

	/* Cache the task's map */
	new_thread->map = parent_task->map;

	/* Chain the thread onto the task's list */
	queue_enter(&parent_task->threads, new_thread, thread_t, task_threads);
	parent_task->thread_count++;
	
	/* So terminating threads don't need to take the task lock to decrement */
	hw_atomic_add(&parent_task->active_thread_count, 1);

	queue_enter(&threads, new_thread, thread_t, threads);
	threads_count++;

	timer_call_setup(&new_thread->wait_timer, thread_timer_expire, new_thread);
	timer_call_setup(&new_thread->depress_timer, thread_depress_expire, new_thread);

	/* Set the thread's scheduling parameters */
	if (parent_task != kernel_task)
		new_thread->sched_mode |= TH_MODE_TIMESHARE;
	new_thread->max_priority = parent_task->max_priority;
	new_thread->task_priority = parent_task->priority;
	new_thread->priority = (priority < 0)? parent_task->priority: priority;
	if (new_thread->priority > new_thread->max_priority)
		new_thread->priority = new_thread->max_priority;
	new_thread->importance =
					new_thread->priority - new_thread->task_priority;
	new_thread->sched_stamp = sched_tick;
	new_thread->pri_shift = sched_pri_shift;
	compute_priority(new_thread, FALSE);

	new_thread->active = TRUE;

	*out_thread = new_thread;

	{
		long	dbg_arg1, dbg_arg2, dbg_arg3, dbg_arg4;

		kdbg_trace_data(parent_task->bsd_info, &dbg_arg2);

		KERNEL_DEBUG_CONSTANT(
					TRACEDBG_CODE(DBG_TRACE_DATA, 1) | DBG_FUNC_NONE,
							(vm_address_t)new_thread, dbg_arg2, 0, 0, 0);

		kdbg_trace_string(parent_task->bsd_info,
							&dbg_arg1, &dbg_arg2, &dbg_arg3, &dbg_arg4);

		KERNEL_DEBUG_CONSTANT(
					TRACEDBG_CODE(DBG_TRACE_STRING, 1) | DBG_FUNC_NONE,
							dbg_arg1, dbg_arg2, dbg_arg3, dbg_arg4, 0);
	}

	DTRACE_PROC1(lwp__create, thread_t, *out_thread);

	return (KERN_SUCCESS);
}
Beispiel #10
0
/*
 * Create a new thread.
 * Doesn't start the thread running.
 */
static kern_return_t
thread_create_internal(
	task_t					parent_task,
	integer_t				priority,
	thread_continue_t		continuation,
	int						options,
#define TH_OPTION_NONE		0x00
#define TH_OPTION_NOCRED	0x01
#define TH_OPTION_NOSUSP	0x02
	thread_t				*out_thread)
{
	thread_t				new_thread;
	static thread_t			first_thread;

	/*
	 *	Allocate a thread and initialize static fields
	 */
	if (first_thread == THREAD_NULL)
		new_thread = first_thread = current_thread();
	else
		new_thread = (thread_t)zalloc(thread_zone);
	if (new_thread == THREAD_NULL)
		return (KERN_RESOURCE_SHORTAGE);

	if (new_thread != first_thread)
		*new_thread = thread_template;

#ifdef MACH_BSD
	new_thread->uthread = uthread_alloc(parent_task, new_thread, (options & TH_OPTION_NOCRED) != 0);
	if (new_thread->uthread == NULL) {
		zfree(thread_zone, new_thread);
		return (KERN_RESOURCE_SHORTAGE);
	}
#endif  /* MACH_BSD */

	if (machine_thread_create(new_thread, parent_task) != KERN_SUCCESS) {
#ifdef MACH_BSD
		void *ut = new_thread->uthread;

		new_thread->uthread = NULL;
		/* cred free may not be necessary */
		uthread_cleanup(parent_task, ut, parent_task->bsd_info);
		uthread_cred_free(ut);
		uthread_zone_free(ut);
#endif  /* MACH_BSD */

		zfree(thread_zone, new_thread);
		return (KERN_FAILURE);
	}

    new_thread->task = parent_task;

	thread_lock_init(new_thread);
	wake_lock_init(new_thread);

	lck_mtx_init(&new_thread->mutex, &thread_lck_grp, &thread_lck_attr);

	ipc_thread_init(new_thread);
	queue_init(&new_thread->held_ulocks);

	new_thread->continuation = continuation;

	lck_mtx_lock(&tasks_threads_lock);
	task_lock(parent_task);

	if (	!parent_task->active || parent_task->halting ||
			((options & TH_OPTION_NOSUSP) != 0 &&
			 	parent_task->suspend_count > 0)	||
			(parent_task->thread_count >= task_threadmax &&
				parent_task != kernel_task)		) {
		task_unlock(parent_task);
		lck_mtx_unlock(&tasks_threads_lock);

#ifdef MACH_BSD
		{
			void *ut = new_thread->uthread;

			new_thread->uthread = NULL;
			uthread_cleanup(parent_task, ut, parent_task->bsd_info);
			/* cred free may not be necessary */
			uthread_cred_free(ut);
			uthread_zone_free(ut);
		}
#endif  /* MACH_BSD */
		ipc_thread_disable(new_thread);
		ipc_thread_terminate(new_thread);
		lck_mtx_destroy(&new_thread->mutex, &thread_lck_grp);
		machine_thread_destroy(new_thread);
		zfree(thread_zone, new_thread);
		return (KERN_FAILURE);
	}

	/* New threads inherit any default state on the task */
	machine_thread_inherit_taskwide(new_thread, parent_task);

	task_reference_internal(parent_task);

	/* Cache the task's map */
	new_thread->map = parent_task->map;

	/* Chain the thread onto the task's list */
	queue_enter(&parent_task->threads, new_thread, thread_t, task_threads);
	parent_task->thread_count++;
	
	/* So terminating threads don't need to take the task lock to decrement */
	hw_atomic_add(&parent_task->active_thread_count, 1);

	/* Protected by the tasks_threads_lock */
	new_thread->thread_id = ++thread_unique_id;

	queue_enter(&threads, new_thread, thread_t, threads);
	threads_count++;

	timer_call_setup(&new_thread->wait_timer, thread_timer_expire, new_thread);
	timer_call_setup(&new_thread->depress_timer, thread_depress_expire, new_thread);

#if CONFIG_COUNTERS
	/*
	 * If parent task has any reservations, they need to be propagated to this
	 * thread.
	 */
	new_thread->t_chud = (TASK_PMC_FLAG == (parent_task->t_chud & TASK_PMC_FLAG)) ? 
		THREAD_PMC_FLAG : 0U;
#endif

	/* Set the thread's scheduling parameters */
	if (parent_task != kernel_task)
		new_thread->sched_mode |= TH_MODE_TIMESHARE;
	new_thread->max_priority = parent_task->max_priority;
	new_thread->task_priority = parent_task->priority;
	new_thread->priority = (priority < 0)? parent_task->priority: priority;
	if (new_thread->priority > new_thread->max_priority)
		new_thread->priority = new_thread->max_priority;
	new_thread->importance =
					new_thread->priority - new_thread->task_priority;
	new_thread->sched_stamp = sched_tick;
	new_thread->pri_shift = sched_pri_shift;
	compute_priority(new_thread, FALSE);

	new_thread->active = TRUE;

	*out_thread = new_thread;

	{
		long	dbg_arg1, dbg_arg2, dbg_arg3, dbg_arg4;

		kdbg_trace_data(parent_task->bsd_info, &dbg_arg2);

		KERNEL_DEBUG_CONSTANT(
					TRACEDBG_CODE(DBG_TRACE_DATA, 1) | DBG_FUNC_NONE,
							(vm_address_t)(uintptr_t)thread_tid(new_thread), dbg_arg2, 0, 0, 0);

		kdbg_trace_string(parent_task->bsd_info,
							&dbg_arg1, &dbg_arg2, &dbg_arg3, &dbg_arg4);

		KERNEL_DEBUG_CONSTANT(
					TRACEDBG_CODE(DBG_TRACE_STRING, 1) | DBG_FUNC_NONE,
							dbg_arg1, dbg_arg2, dbg_arg3, dbg_arg4, 0);
	}

	DTRACE_PROC1(lwp__create, thread_t, *out_thread);

	return (KERN_SUCCESS);
}
Beispiel #11
0
void
lck_grp_reference(
	lck_grp_t	*grp)
{
	(void)hw_atomic_add(&grp->lck_grp_refcnt, 1);
}
Beispiel #12
0
/*
 *	Routine:	semaphore_reference
 *
 *	Take out a reference on a semaphore.  This keeps the data structure
 *	in existence (but the semaphore may be deactivated).
 */
void
semaphore_reference(
	semaphore_t		semaphore)
{
	(void)hw_atomic_add(&semaphore->ref_count, 1);
}
Beispiel #13
0
/**
 * pmap_reference
 *
 * Increment reference count of the specified pmap.
 */
void
pmap_reference(pmap_t pmap)
{
    if (pmap != PMAP_NULL)
        (void)hw_atomic_add(&pmap->ref_count, 1); /* Bump the count */
}