/*
* Routine: port_name_to_clock
* Purpose:
* Convert from a clock name to a clock pointer.
*/
clock_t
port_name_to_clock(
mach_port_name_t clock_name)
{
clock_t clock = CLOCK_NULL;
ipc_space_t space;
ipc_port_t port;
if (clock_name == 0)
return (clock);
space = current_space();
if (ipc_port_translate_send(space, clock_name, &port) != KERN_SUCCESS)
return (clock);
if (ip_active(port) && (ip_kotype(port) == IKOT_CLOCK))
clock = (clock_t) port->ip_kobject;
ip_unlock(port);
return (clock);
}
/*
* thread_switch:
*
* Context switch. User may supply thread hint.
*/
kern_return_t
thread_switch(
struct thread_switch_args *args)
{
thread_t thread = THREAD_NULL;
thread_t 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;
uint32_t scale_factor = NSEC_PER_MSEC;
boolean_t reenable_workq_callback = FALSE;
boolean_t depress_option = FALSE;
boolean_t wait_option = FALSE;
/*
* Validate and process option.
*/
switch (option) {
case SWITCH_OPTION_NONE:
workqueue_thread_yielded();
break;
case SWITCH_OPTION_WAIT:
wait_option = TRUE;
workqueue_thread_yielded();
break;
case SWITCH_OPTION_DEPRESS:
depress_option = TRUE;
workqueue_thread_yielded();
break;
case SWITCH_OPTION_DISPATCH_CONTENTION:
scale_factor = NSEC_PER_USEC;
wait_option = TRUE;
if (thread_switch_disable_workqueue_sched_callback())
reenable_workq_callback = TRUE;
break;
case SWITCH_OPTION_OSLOCK_DEPRESS:
depress_option = TRUE;
if (thread_switch_disable_workqueue_sched_callback())
reenable_workq_callback = TRUE;
break;
case SWITCH_OPTION_OSLOCK_WAIT:
wait_option = TRUE;
if (thread_switch_disable_workqueue_sched_callback())
reenable_workq_callback = TRUE;
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);
ip_release(port);
if (thread == self) {
thread_deallocate(thread);
thread = THREAD_NULL;
}
}
}
if (option == SWITCH_OPTION_OSLOCK_DEPRESS || option == SWITCH_OPTION_OSLOCK_WAIT) {
if (thread != THREAD_NULL) {
if (thread->task != self->task) {
/*
* OSLock boosting only applies to other threads
* in your same task (even if you have a port for
* a thread in another task)
*/
thread_deallocate(thread);
thread = THREAD_NULL;
} else {
/*
* Attempt to kick the lock owner up to our same IO throttling tier.
* If the thread is currently blocked in throttle_lowpri_io(),
* it will immediately break out.
*
* TODO: SFI break out?
*/
int new_policy = proc_get_effective_thread_policy(self, TASK_POLICY_IO);
set_thread_iotier_override(thread, new_policy);
}
}
}
/*
* Try to handoff if supplied.
*/
if (thread != THREAD_NULL) {
spl_t s = splsched();
/* This may return a different thread if the target is pushing on something */
thread_t pulled_thread = thread_run_queue_remove_for_handoff(thread);
KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED,MACH_SCHED_THREAD_SWITCH)|DBG_FUNC_NONE,
thread_tid(thread), thread->state,
pulled_thread ? TRUE : FALSE, 0, 0);
if (pulled_thread != THREAD_NULL) {
/* We can't be dropping the last ref here */
thread_deallocate_safe(thread);
if (wait_option)
assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE,
option_time, scale_factor);
else if (depress_option)
thread_depress_ms(option_time);
self->saved.swtch.option = option;
self->saved.swtch.reenable_workq_callback = reenable_workq_callback;
thread_run(self, (thread_continue_t)thread_switch_continue, NULL, pulled_thread);
/* NOTREACHED */
panic("returned from thread_run!");
}
splx(s);
thread_deallocate(thread);
}
if (wait_option)
assert_wait_timeout((event_t)assert_wait_timeout, THREAD_ABORTSAFE, option_time, scale_factor);
else if (depress_option)
thread_depress_ms(option_time);
self->saved.swtch.option = option;
self->saved.swtch.reenable_workq_callback = reenable_workq_callback;
thread_block_reason((thread_continue_t)thread_switch_continue, NULL, AST_YIELD);
if (depress_option)
thread_depress_abort_internal(self);
if (reenable_workq_callback)
thread_switch_enable_workqueue_sched_callback();
return (KERN_SUCCESS);
}
/*
* thread_switch:
*
* Context switch. User may supply thread hint.
*
* Fixed priority threads that call this get what they asked for
* even if that violates priority order.
*/
kern_return_t thread_switch(
mach_port_t thread_name,
int option,
mach_msg_timeout_t option_time)
{
thread_t cur_thread = current_thread();
processor_t myprocessor;
ipc_port_t port;
/*
* Process option.
*/
switch (option) {
case SWITCH_OPTION_NONE:
/*
* Nothing to do.
*/
break;
case SWITCH_OPTION_DEPRESS:
/*
* Depress priority for given time.
*/
thread_depress_priority(cur_thread, option_time);
break;
case SWITCH_OPTION_WAIT:
thread_will_wait_with_timeout(cur_thread, option_time);
break;
default:
return(KERN_INVALID_ARGUMENT);
}
#ifndef MIGRATING_THREADS /* XXX thread_run defunct */
/*
* Check and act on thread hint if appropriate.
*/
if ((thread_name != 0) &&
(ipc_port_translate_send(cur_thread->task->itk_space,
thread_name, &port) == KERN_SUCCESS)) {
/* port is locked, but it might not be active */
/*
* Get corresponding thread.
*/
if (ip_active(port) && (ip_kotype(port) == IKOT_THREAD)) {
thread_t thread;
spl_t s;
thread = (thread_t) port->ip_kobject;
/*
* Check if the thread is in the right pset. Then
* pull it off its run queue. If it
* doesn't come, then it's not eligible.
*/
s = splsched();
thread_lock(thread);
if ((thread->processor_set == cur_thread->processor_set)
&& (rem_runq(thread) != RUN_QUEUE_NULL)) {
/*
* Hah, got it!!
*/
thread_unlock(thread);
(void) splx(s);
ip_unlock(port);
/* XXX thread might disappear on us now? */
#if MACH_FIXPRI
if (thread->policy == POLICY_FIXEDPRI) {
myprocessor = current_processor();
myprocessor->quantum = thread->sched_data;
myprocessor->first_quantum = TRUE;
}
#endif /* MACH_FIXPRI */
counter(c_thread_switch_handoff++);
thread_run(thread_switch_continue, thread);
/*
* Restore depressed priority
*/
if (cur_thread->depress_priority >= 0)
(void) thread_depress_abort(cur_thread);
return(KERN_SUCCESS);
}
thread_unlock(thread);
(void) splx(s);
}
ip_unlock(port);
}
#endif /* not MIGRATING_THREADS */
/*
* No handoff hint supplied, or hint was wrong. Call thread_block() in
* hopes of running something else. If nothing else is runnable,
* thread_block will detect this. WARNING: thread_switch with no
* option will not do anything useful if the thread calling it is the
* highest priority thread (can easily happen with a collection
* of timesharing threads).
*/
#if NCPUS > 1
myprocessor = current_processor();
if (myprocessor->processor_set->runq.count > 0 ||
myprocessor->runq.count > 0)
#endif /* NCPUS > 1 */
{
counter(c_thread_switch_block++);
thread_block(thread_switch_continue);
}
/*
* Restore depressed priority
*/
if (cur_thread->depress_priority >= 0)
(void) thread_depress_abort(cur_thread);
return(KERN_SUCCESS);
}
