[apple/xnu.git] / osfmk / kern / syscall_subr.c

/*
 * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 */

#include <mach/boolean.h>
#include <mach/thread_switch.h>
#include <ipc/ipc_port.h>
#include <ipc/ipc_space.h>
#include <kern/counters.h>
#include <kern/ipc_kobject.h>
#include <kern/processor.h>
#include <kern/sched.h>
#include <kern/sched_prim.h>
#include <kern/spl.h>
#include <kern/task.h>
#include <kern/thread.h>
#include <mach/policy.h>

#include <kern/syscall_subr.h>
#include <mach/mach_host_server.h>
#include <mach/mach_syscalls.h>

/*
 *	swtch and swtch_pri both attempt to context switch (logic in
 *	thread_block no-ops the context switch if nothing would happen).
 *	A boolean is returned that indicates whether there is anything
 *	else runnable.
 *
 *	This boolean can be used by a thread waiting on a
 *	lock or condition:  If FALSE is returned, the thread is justified
 *	in becoming a resource hog by continuing to spin because there's
 *	nothing else useful that the processor could do.  If TRUE is
 *	returned, the thread should make one more check on the
 *	lock and then be a good citizen and really suspend.
 */

static void
swtch_continue(void)
{
	register processor_t	myprocessor;
    boolean_t				result;

    disable_preemption();
	myprocessor = current_processor();
	result =		myprocessor->runq.count > 0					||
				myprocessor->processor_set->runq.count > 0;
	enable_preemption();

	thread_syscall_return(result);
	/*NOTREACHED*/
}

boolean_t
swtch(
	__unused struct swtch_args *args)
{
	register processor_t	myprocessor;
	boolean_t				result;

	disable_preemption();
	myprocessor = current_processor();
	if (		myprocessor->runq.count == 0				&&
			myprocessor->processor_set->runq.count == 0			) {
		mp_enable_preemption();

		return (FALSE);
	}
	enable_preemption();

	counter(c_swtch_block++);

	thread_block_reason((thread_continue_t)swtch_continue, NULL, AST_YIELD);

	disable_preemption();
	myprocessor = current_processor();
	result =		myprocessor->runq.count > 0					||
				myprocessor->processor_set->runq.count > 0;
	enable_preemption();

	return (result);
}

static void
swtch_pri_continue(void)
{
	register processor_t	myprocessor;
    boolean_t				result;

	thread_depress_abort_internal(current_thread());

    disable_preemption();
	myprocessor = current_processor();
	result =		myprocessor->runq.count > 0					||
				myprocessor->processor_set->runq.count > 0;
	mp_enable_preemption();

	thread_syscall_return(result);
	/*NOTREACHED*/
}

boolean_t
swtch_pri(
__unused	struct swtch_pri_args *args)
{
	register processor_t	myprocessor;
	boolean_t				result;

	disable_preemption();
	myprocessor = current_processor();
	if (	myprocessor->runq.count == 0					&&
			myprocessor->processor_set->runq.count == 0			) {
		mp_enable_preemption();

		return (FALSE);
	}
	enable_preemption();

	counter(c_swtch_pri_block++);

	thread_depress_abstime(std_quantum);

	thread_block_reason((thread_continue_t)swtch_pri_continue, NULL, AST_YIELD);

	thread_depress_abort_internal(current_thread());

	disable_preemption();
	myprocessor = current_processor();
	result =	myprocessor->runq.count > 0						||
				myprocessor->processor_set->runq.count > 0;
	enable_preemption();

	return (result);
}

static void
thread_switch_continue(void)
{
	register thread_t	self = current_thread();
	int					option = self->saved.swtch.option;

	if (option == SWITCH_OPTION_DEPRESS)
		thread_depress_abort_internal(self);

	thread_syscall_return(KERN_SUCCESS);
	/*NOTREACHED*/
}

/*
 *	thread_switch:
 *
 *	Context switch.  User may supply thread hint.
 */
kern_return_t
thread_switch(
	struct thread_switch_args *args)
{
	register thread_t		thread, self = current_thread();
	mach_port_name_t		thread_name = args->thread_name;
	int						option = args->option;
	mach_msg_timeout_t		option_time = args->option_time;

    /*
     *	Process option.
     */
    switch (option) {

	case SWITCH_OPTION_NONE:
	case SWITCH_OPTION_DEPRESS:
	case SWITCH_OPTION_WAIT:
	    break;

	default:
	    return (KERN_INVALID_ARGUMENT);
    }

	/*
	 * Translate the port name if supplied.
	 */
    if (thread_name != MACH_PORT_NULL) {
		ipc_port_t			port;

		if (ipc_port_translate_send(self->task->itk_space,
									thread_name, &port) == KERN_SUCCESS) {
			ip_reference(port);
			ip_unlock(port);

			thread = convert_port_to_thread(port);
			ipc_port_release(port);

			if (thread == self) {
				thread_deallocate_internal(thread);
				thread = THREAD_NULL;
			}
		}
		else
			thread = THREAD_NULL;
	}
	else
		thread = THREAD_NULL;

	/*
	 * Try to handoff if supplied.
	 */
	if (thread != THREAD_NULL) {
		processor_t		processor;
		spl_t			s;

		s = splsched();
		thread_lock(thread);

		/*
		 *	Check if the thread is in the right pset,
		 *	is not bound to a different processor,
		 *	and that realtime is not involved.
		 *
		 *	Next, pull it off its run queue.  If it
		 *	doesn't come, it's not eligible.
		 */
		processor = current_processor();
		if (processor->current_pri < BASEPRI_RTQUEUES			&&
			thread->sched_pri < BASEPRI_RTQUEUES				&&
			thread->processor_set == processor->processor_set	&&
			(thread->bound_processor == PROCESSOR_NULL	||
			 thread->bound_processor == processor)				&&
			run_queue_remove(thread) != RUN_QUEUE_NULL			) {
			/*
			 *	Hah, got it!!
			 */
			thread_unlock(thread);

			thread_deallocate_internal(thread);

			if (option == SWITCH_OPTION_WAIT)
				assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE,
														option_time, 1000*NSEC_PER_USEC);
			else
			if (option == SWITCH_OPTION_DEPRESS)
				thread_depress_ms(option_time);

			self->saved.swtch.option = option;

			thread_run(self, (thread_continue_t)thread_switch_continue, NULL, thread);
			/* NOTREACHED */
		}

		thread_unlock(thread);
		splx(s);

		thread_deallocate(thread);
	}
		
	if (option == SWITCH_OPTION_WAIT)
		assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE, option_time, 1000*NSEC_PER_USEC);
	else
	if (option == SWITCH_OPTION_DEPRESS)
		thread_depress_ms(option_time);
	  
	self->saved.swtch.option = option;

	thread_block_reason((thread_continue_t)thread_switch_continue, NULL, AST_YIELD);

	if (option == SWITCH_OPTION_DEPRESS)
		thread_depress_abort_internal(self);

    return (KERN_SUCCESS);
}

/*
 * Depress thread's priority to lowest possible for the specified interval,
 * with a value of zero resulting in no timeout being scheduled.
 */
void
thread_depress_abstime(
	uint64_t				interval)
{
	register thread_t		self = current_thread();
	uint64_t				deadline;
    spl_t					s;

    s = splsched();
    thread_lock(self);
	if (!(self->sched_mode & TH_MODE_ISDEPRESSED)) {
		processor_t		myprocessor = self->last_processor;

		self->sched_pri = DEPRESSPRI;
		myprocessor->current_pri = self->sched_pri;
		self->sched_mode &= ~TH_MODE_PREEMPT;
		self->sched_mode |= TH_MODE_DEPRESS;

		if (interval != 0) {
			clock_absolutetime_interval_to_deadline(interval, &deadline);
			if (!timer_call_enter(&self->depress_timer, deadline))
				self->depress_timer_active++;
		}
	}
	thread_unlock(self);
    splx(s);
}

void
thread_depress_ms(
	mach_msg_timeout_t		interval)
{
	uint64_t		abstime;

	clock_interval_to_absolutetime_interval(
							interval, 1000*NSEC_PER_USEC, &abstime);
	thread_depress_abstime(abstime);
}

/*
 *	Priority depression expiration.
 */
void
thread_depress_expire(
	void			*p0,
	__unused void	*p1)
{
	thread_t		thread = p0;
    spl_t			s;

    s = splsched();
    thread_lock(thread);
	if (--thread->depress_timer_active == 0) {
		thread->sched_mode &= ~TH_MODE_ISDEPRESSED;
		compute_priority(thread, FALSE);
	}
    thread_unlock(thread);
    splx(s);
}

/*
 *	Prematurely abort priority depression if there is one.
 */
kern_return_t
thread_depress_abort_internal(
	thread_t				thread)
{
    kern_return_t 			result = KERN_NOT_DEPRESSED;
    spl_t					s;

    s = splsched();
    thread_lock(thread);
	if (!(thread->sched_mode & TH_MODE_POLLDEPRESS)) {
		if (thread->sched_mode & TH_MODE_ISDEPRESSED) {
			thread->sched_mode &= ~TH_MODE_ISDEPRESSED;
			compute_priority(thread, FALSE);
			result = KERN_SUCCESS;
		}

		if (timer_call_cancel(&thread->depress_timer))
			thread->depress_timer_active--;
	}
	thread_unlock(thread);
    splx(s);

    return (result);
}

void
thread_poll_yield(
	thread_t		self)
{
	spl_t			s;

	assert(self == current_thread());

	s = splsched();
	if (!(self->sched_mode & (TH_MODE_REALTIME|TH_MODE_TIMESHARE))) {
		uint64_t			total_computation, abstime;

		abstime = mach_absolute_time();
		total_computation = abstime - self->computation_epoch;
		total_computation += self->computation_metered;
		if (total_computation >= max_poll_computation) {
			processor_t		myprocessor = current_processor();
			ast_t			preempt;

			thread_lock(self);
			if (!(self->sched_mode & TH_MODE_ISDEPRESSED)) {
				self->sched_pri = DEPRESSPRI;
				myprocessor->current_pri = self->sched_pri;
				self->sched_mode &= ~TH_MODE_PREEMPT;
			}
			self->computation_epoch = abstime;
			self->computation_metered = 0;
			self->sched_mode |= TH_MODE_POLLDEPRESS;

			abstime += (total_computation >> sched_poll_yield_shift);
			if (!timer_call_enter(&self->depress_timer, abstime))
				self->depress_timer_active++;
			thread_unlock(self);

			if ((preempt = csw_check(self, myprocessor)) != AST_NONE)
				ast_on(preempt);
		}
	}
	splx(s);
}
Commit	Line	Data
1c79356b	1	/*
91447636	2	* Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
1c79356b	3	*
8f6c56a5	4	* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
1c79356b	5	*
8f6c56a5 A	6	* This file contains Original Code and/or Modifications of Original Code
	7	* as defined in and that are subject to the Apple Public Source License
	8	* Version 2.0 (the 'License'). You may not use this file except in
	9	* compliance with the License. The rights granted to you under the License
	10	* may not be used to create, or enable the creation or redistribution of,
	11	* unlawful or unlicensed copies of an Apple operating system, or to
	12	* circumvent, violate, or enable the circumvention or violation of, any
	13	* terms of an Apple operating system software license agreement.
	14	*
	15	* Please obtain a copy of the License at
	16	* http://www.opensource.apple.com/apsl/ and read it before using this file.
	17	*
	18	* The Original Code and all software distributed under the License are
	19	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	20	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	21	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	22	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	23	* Please see the License for the specific language governing rights and
8ad349bb	24	* limitations under the License.
8f6c56a5 A	25	*
8f6c56a5 A	26	* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
1c79356b A	27	*/
	28	/*
	29	* @OSF_COPYRIGHT@
	30	*/
	31	/*
	32	* Mach Operating System
	33	* Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
	34	* All Rights Reserved.
	35	*
	36	* Permission to use, copy, modify and distribute this software and its
	37	* documentation is hereby granted, provided that both the copyright
	38	* notice and this permission notice appear in all copies of the
	39	* software, derivative works or modified versions, and any portions
	40	* thereof, and that both notices appear in supporting documentation.
	41	*
	42	* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
	43	* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
	44	* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
	45	*
	46	* Carnegie Mellon requests users of this software to return to
	47	*
	48	* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
	49	* School of Computer Science
	50	* Carnegie Mellon University
	51	* Pittsburgh PA 15213-3890
	52	*
	53	* any improvements or extensions that they make and grant Carnegie Mellon
	54	* the rights to redistribute these changes.
	55	*/
	56	/*
	57	*/
	58
1c79356b A	59	#include <mach/boolean.h>
	60	#include <mach/thread_switch.h>
	61	#include <ipc/ipc_port.h>
	62	#include <ipc/ipc_space.h>
	63	#include <kern/counters.h>
1c79356b A	64	#include <kern/ipc_kobject.h>
	65	#include <kern/processor.h>
	66	#include <kern/sched.h>
	67	#include <kern/sched_prim.h>
	68	#include <kern/spl.h>
	69	#include <kern/task.h>
	70	#include <kern/thread.h>
1c79356b A	71	#include <mach/policy.h>
	72
	73	#include <kern/syscall_subr.h>
	74	#include <mach/mach_host_server.h>
	75	#include <mach/mach_syscalls.h>
	76
1c79356b A	77	/*
	78	* swtch and swtch_pri both attempt to context switch (logic in
	79	* thread_block no-ops the context switch if nothing would happen).
	80	* A boolean is returned that indicates whether there is anything
	81	* else runnable.
	82	*
	83	* This boolean can be used by a thread waiting on a
	84	* lock or condition: If FALSE is returned, the thread is justified
	85	* in becoming a resource hog by continuing to spin because there's
	86	* nothing else useful that the processor could do. If TRUE is
	87	* returned, the thread should make one more check on the
	88	* lock and then be a good citizen and really suspend.
	89	*/
	90
91447636	91	static void
0b4e3aa0	92	swtch_continue(void)
1c79356b	93	{
0b4e3aa0 A	94	register processor_t myprocessor;
0b4e3aa0 A	95	boolean_t result;
1c79356b	96
91447636	97	disable_preemption();
1c79356b	98	myprocessor = current_processor();
0b4e3aa0 A	99	result = myprocessor->runq.count > 0 \|\|
0b4e3aa0 A	100	myprocessor->processor_set->runq.count > 0;
91447636	101	enable_preemption();
1c79356b	102
0b4e3aa0 A	103	thread_syscall_return(result);
	104	/NOTREACHED/
	105	}
1c79356b A	106
1c79356b A	107	boolean_t
91447636 A	108	swtch(
91447636 A	109	__unused struct swtch_args *args)
1c79356b A	110	{
	111	register processor_t myprocessor;
	112	boolean_t result;
	113
91447636	114	disable_preemption();
1c79356b	115	myprocessor = current_processor();
0b4e3aa0	116	if ( myprocessor->runq.count == 0 &&
1c79356b A	117	myprocessor->processor_set->runq.count == 0 ) {
	118	mp_enable_preemption();
	119
	120	return (FALSE);
	121	}
91447636	122	enable_preemption();
1c79356b A	123
	124	counter(c_swtch_block++);
	125
91447636	126	thread_block_reason((thread_continue_t)swtch_continue, NULL, AST_YIELD);
1c79356b	127
91447636	128	disable_preemption();
1c79356b	129	myprocessor = current_processor();
0b4e3aa0 A	130	result = myprocessor->runq.count > 0 \|\|
0b4e3aa0 A	131	myprocessor->processor_set->runq.count > 0;
91447636	132	enable_preemption();
1c79356b A	133
	134	return (result);
	135	}
	136
91447636	137	static void
0b4e3aa0 A	138	swtch_pri_continue(void)
	139	{
	140	register processor_t myprocessor;
	141	boolean_t result;
	142
91447636	143	thread_depress_abort_internal(current_thread());
0b4e3aa0	144
91447636	145	disable_preemption();
0b4e3aa0 A	146	myprocessor = current_processor();
	147	result = myprocessor->runq.count > 0 \|\|
	148	myprocessor->processor_set->runq.count > 0;
	149	mp_enable_preemption();
	150
	151	thread_syscall_return(result);
	152	/NOTREACHED/
	153	}
	154
1c79356b A	155	boolean_t
1c79356b A	156	swtch_pri(
91447636	157	__unused struct swtch_pri_args *args)
1c79356b	158	{
1c79356b A	159	register processor_t myprocessor;
1c79356b A	160	boolean_t result;
1c79356b	161
91447636	162	disable_preemption();
1c79356b	163	myprocessor = current_processor();
0b4e3aa0	164	if ( myprocessor->runq.count == 0 &&
1c79356b	165	myprocessor->processor_set->runq.count == 0 ) {
0b4e3aa0	166	mp_enable_preemption();
1c79356b A	167
	168	return (FALSE);
	169	}
91447636	170	enable_preemption();
0b4e3aa0 A	171
	172	counter(c_swtch_pri_block++);
	173
91447636	174	thread_depress_abstime(std_quantum);
1c79356b	175
91447636	176	thread_block_reason((thread_continue_t)swtch_pri_continue, NULL, AST_YIELD);
1c79356b	177
91447636	178	thread_depress_abort_internal(current_thread());
1c79356b	179
91447636	180	disable_preemption();
1c79356b	181	myprocessor = current_processor();
0b4e3aa0 A	182	result = myprocessor->runq.count > 0 \|\|
0b4e3aa0 A	183	myprocessor->processor_set->runq.count > 0;
91447636	184	enable_preemption();
1c79356b A	185
	186	return (result);
	187	}
	188
91447636 A	189	static void
	190	thread_switch_continue(void)
	191	{
	192	register thread_t self = current_thread();
	193	int option = self->saved.swtch.option;
	194
	195	if (option == SWITCH_OPTION_DEPRESS)
	196	thread_depress_abort_internal(self);
	197
	198	thread_syscall_return(KERN_SUCCESS);
	199	/NOTREACHED/
	200	}
	201
1c79356b A	202	/*
	203	* thread_switch:
	204	*
	205	* Context switch. User may supply thread hint.
	206	*/
	207	kern_return_t
	208	thread_switch(
91447636	209	struct thread_switch_args *args)
1c79356b	210	{
91447636 A	211	register thread_t thread, self = current_thread();
	212	mach_port_name_t thread_name = args->thread_name;
	213	int option = args->option;
	214	mach_msg_timeout_t option_time = args->option_time;
1c79356b A	215
	216	/*
	217	* Process option.
	218	*/
	219	switch (option) {
	220
	221	case SWITCH_OPTION_NONE:
	222	case SWITCH_OPTION_DEPRESS:
	223	case SWITCH_OPTION_WAIT:
	224	break;
	225
	226	default:
	227	return (KERN_INVALID_ARGUMENT);
	228	}
	229
91447636 A	230	/*
	231	* Translate the port name if supplied.
	232	*/
1c79356b A	233	if (thread_name != MACH_PORT_NULL) {
	234	ipc_port_t port;
	235
91447636	236	if (ipc_port_translate_send(self->task->itk_space,
1c79356b A	237	thread_name, &port) == KERN_SUCCESS) {
	238	ip_reference(port);
	239	ip_unlock(port);
	240
91447636	241	thread = convert_port_to_thread(port);
1c79356b	242	ipc_port_release(port);
91447636 A	243
	244	if (thread == self) {
	245	thread_deallocate_internal(thread);
	246	thread = THREAD_NULL;
	247	}
1c79356b	248	}
91447636 A	249	else
91447636 A	250	thread = THREAD_NULL;
1c79356b	251	}
91447636 A	252	else
	253	thread = THREAD_NULL;
	254
	255	/*
	256	* Try to handoff if supplied.
	257	*/
	258	if (thread != THREAD_NULL) {
	259	processor_t processor;
	260	spl_t s;
	261
	262	s = splsched();
	263	thread_lock(thread);
	264
	265	/*
	266	* Check if the thread is in the right pset,
	267	* is not bound to a different processor,
	268	* and that realtime is not involved.
	269	*
	270	* Next, pull it off its run queue. If it
	271	* doesn't come, it's not eligible.
	272	*/
	273	processor = current_processor();
	274	if (processor->current_pri < BASEPRI_RTQUEUES &&
	275	thread->sched_pri < BASEPRI_RTQUEUES &&
	276	thread->processor_set == processor->processor_set &&
	277	(thread->bound_processor == PROCESSOR_NULL \|\|
	278	thread->bound_processor == processor) &&
	279	run_queue_remove(thread) != RUN_QUEUE_NULL ) {
	280	/*
	281	* Hah, got it!!
	282	*/
	283	thread_unlock(thread);
	284
	285	thread_deallocate_internal(thread);
	286
	287	if (option == SWITCH_OPTION_WAIT)
	288	assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE,
	289	option_time, 1000*NSEC_PER_USEC);
	290	else
	291	if (option == SWITCH_OPTION_DEPRESS)
	292	thread_depress_ms(option_time);
	293
	294	self->saved.swtch.option = option;
	295
	296	thread_run(self, (thread_continue_t)thread_switch_continue, NULL, thread);
	297	/* NOTREACHED */
	298	}
	299
	300	thread_unlock(thread);
	301	splx(s);
	302
	303	thread_deallocate(thread);
	304	}
	305
	306	if (option == SWITCH_OPTION_WAIT)
	307	assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE, option_time, 1000*NSEC_PER_USEC);
	308	else
	309	if (option == SWITCH_OPTION_DEPRESS)
	310	thread_depress_ms(option_time);
	311
	312	self->saved.swtch.option = option;
	313
	314	thread_block_reason((thread_continue_t)thread_switch_continue, NULL, AST_YIELD);
	315
316	if (option == SWITCH_OPTION_DEPRESS)
317	thread_depress_abort_internal(self);
318
319	return (KERN_SUCCESS);
320	}
1c79356b	321
91447636 A	322	/*
	323	* Depress thread's priority to lowest possible for the specified interval,
	324	* with a value of zero resulting in no timeout being scheduled.
	325	*/
	326	void
	327	thread_depress_abstime(
	328	uint64_t interval)
	329	{
	330	register thread_t self = current_thread();
	331	uint64_t deadline;
	332	spl_t s;
	333
	334	s = splsched();
	335	thread_lock(self);
	336	if (!(self->sched_mode & TH_MODE_ISDEPRESSED)) {
	337	processor_t myprocessor = self->last_processor;
	338
	339	self->sched_pri = DEPRESSPRI;
	340	myprocessor->current_pri = self->sched_pri;
	341	self->sched_mode &= ~TH_MODE_PREEMPT;
	342	self->sched_mode \|= TH_MODE_DEPRESS;
	343
	344	if (interval != 0) {
	345	clock_absolutetime_interval_to_deadline(interval, &deadline);
	346	if (!timer_call_enter(&self->depress_timer, deadline))
	347	self->depress_timer_active++;
	348	}
	349	}
	350	thread_unlock(self);
	351	splx(s);
	352	}
	353
	354	void
	355	thread_depress_ms(
	356	mach_msg_timeout_t interval)
	357	{
	358	uint64_t abstime;
	359
	360	clock_interval_to_absolutetime_interval(
	361	interval, 1000*NSEC_PER_USEC, &abstime);
	362	thread_depress_abstime(abstime);
	363	}
	364
	365	/*
	366	* Priority depression expiration.
	367	*/
	368	void
	369	thread_depress_expire(
	370	void *p0,
	371	__unused void *p1)
	372	{
	373	thread_t thread = p0;
	374	spl_t s;
	375
	376	s = splsched();
	377	thread_lock(thread);
	378	if (--thread->depress_timer_active == 0) {
	379	thread->sched_mode &= ~TH_MODE_ISDEPRESSED;
	380	compute_priority(thread, FALSE);
	381	}
	382	thread_unlock(thread);
	383	splx(s);
	384	}
	385
386	/*
387	* Prematurely abort priority depression if there is one.
388	*/
389	kern_return_t
390	thread_depress_abort_internal(
391	thread_t thread)
392	{
393	kern_return_t result = KERN_NOT_DEPRESSED;
394	spl_t s;
395
396	s = splsched();
397	thread_lock(thread);
398	if (!(thread->sched_mode & TH_MODE_POLLDEPRESS)) {
399	if (thread->sched_mode & TH_MODE_ISDEPRESSED) {
400	thread->sched_mode &= ~TH_MODE_ISDEPRESSED;
401	compute_priority(thread, FALSE);
402	result = KERN_SUCCESS;
403	}
404
405	if (timer_call_cancel(&thread->depress_timer))
406	thread->depress_timer_active--;
407	}
408	thread_unlock(thread);
409	splx(s);
410
411	return (result);
412	}
413
414	void
415	thread_poll_yield(
416	thread_t self)
417	{
418	spl_t s;
419
420	assert(self == current_thread());
421
422	s = splsched();
423	if (!(self->sched_mode & (TH_MODE_REALTIME\|TH_MODE_TIMESHARE))) {
424	uint64_t total_computation, abstime;
425
426	abstime = mach_absolute_time();
427	total_computation = abstime - self->computation_epoch;
428	total_computation += self->computation_metered;
429	if (total_computation >= max_poll_computation) {
430	processor_t myprocessor = current_processor();
431	ast_t preempt;
432
433	thread_lock(self);
434	if (!(self->sched_mode & TH_MODE_ISDEPRESSED)) {
435	self->sched_pri = DEPRESSPRI;
436	myprocessor->current_pri = self->sched_pri;
437	self->sched_mode &= ~TH_MODE_PREEMPT;
438	}
439	self->computation_epoch = abstime;
440	self->computation_metered = 0;
441	self->sched_mode \|= TH_MODE_POLLDEPRESS;
442
443	abstime += (total_computation >> sched_poll_yield_shift);
444	if (!timer_call_enter(&self->depress_timer, abstime))
445	self->depress_timer_active++;
446	thread_unlock(self);
447
448	if ((preempt = csw_check(self, myprocessor)) != AST_NONE)
449	ast_on(preempt);
450	}
451	}
452	splx(s);
1c79356b	453	}