system/kernel/thread.cpp

/*
 * Copyright 2002-2007, Axel Dörfler, axeld@pinc-software.de.
 * Distributed under the terms of the MIT License.
 *
 * Copyright 2001-2002, Travis Geiselbrecht. All rights reserved.
 * Distributed under the terms of the NewOS License.
 */

/*! Threading routines */


#include <thread.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/resource.h>

#include <OS.h>

#include <util/AutoLock.h>
#include <util/khash.h>

#include <boot/kernel_args.h>
#include <condition_variable.h>
#include <cpu.h>
#include <int.h>
#include <kimage.h>
#include <kscheduler.h>
#include <ksignal.h>
#include <smp.h>
#include <syscalls.h>
#include <team.h>
#include <tls.h>
#include <user_runtime.h>
#include <vfs.h>
#include <vm.h>
#include <vm_address_space.h>
#include <wait_for_objects.h>


//#define TRACE_THREAD
#ifdef TRACE_THREAD
#	define TRACE(x) dprintf x
#else
#	define TRACE(x) ;
#endif


#define THREAD_MAX_MESSAGE_SIZE		65536

// used to pass messages between thread_exit and thread_exit2

struct thread_exit_args {
	struct thread	*thread;
	area_id			old_kernel_stack;
	uint32			death_stack;
	sem_id			death_sem;
	team_id			original_team_id;
};

struct thread_key {
	thread_id id;
};

// global
spinlock thread_spinlock = 0;

// thread list
static struct thread sIdleThreads[B_MAX_CPU_COUNT];
static hash_table *sThreadHash = NULL;
static thread_id sNextThreadID = 1;

// some arbitrary chosen limits - should probably depend on the available
// memory (the limit is not yet enforced)
static int32 sMaxThreads = 4096;
static int32 sUsedThreads = 0;

static sem_id sSnoozeSem = -1;

// death stacks - used temporarily as a thread cleans itself up
struct death_stack {
	area_id	area;
	addr_t	address;
	bool	in_use;
};
static struct death_stack *sDeathStacks;
static unsigned int sNumDeathStacks;
static unsigned int volatile sDeathStackBitmap;
static sem_id sDeathStackSem;
static spinlock sDeathStackLock = 0;

// The dead queue is used as a pool from which to retrieve and reuse previously
// allocated thread structs when creating a new thread. It should be gone once
// the slab allocator is in.
struct thread_queue dead_q;

static void thread_kthread_entry(void);
static void thread_kthread_exit(void);


/*!
	Inserts a thread into a team.
	You must hold the team lock when you call this function.
*/
static void
insert_thread_into_team(struct team *team, struct thread *thread)
{
	thread->team_next = team->thread_list;
	team->thread_list = thread;
	team->num_threads++;

	if (team->num_threads == 1) {
		// this was the first thread
		team->main_thread = thread;
	}
	thread->team = team;
}


/*!
	Removes a thread from a team.
	You must hold the team lock when you call this function.
*/
static void
remove_thread_from_team(struct team *team, struct thread *thread)
{
	struct thread *temp, *last = NULL;

	for (temp = team->thread_list; temp != NULL; temp = temp->team_next) {
		if (temp == thread) {
			if (last == NULL)
				team->thread_list = temp->team_next;
			else
				last->team_next = temp->team_next;

			team->num_threads--;
			break;
		}
		last = temp;
	}
}


static int
thread_struct_compare(void *_t, const void *_key)
{
	struct thread *thread = (struct thread*)_t;
	const struct thread_key *key = (const struct thread_key*)_key;

	if (thread->id == key->id)
		return 0;

	return 1;
}


static uint32
thread_struct_hash(void *_t, const void *_key, uint32 range)
{
	struct thread *thread = (struct thread*)_t;
	const struct thread_key *key = (const struct thread_key*)_key;

	if (thread != NULL)
		return thread->id % range;

	return (uint32)key->id % range;
}


static void
reset_signals(struct thread *thread)
{
	thread->sig_pending = 0;
	thread->sig_block_mask = 0;
	memset(thread->sig_action, 0, 32 * sizeof(struct sigaction));
	thread->signal_stack_base = 0;
	thread->signal_stack_size = 0;
	thread->signal_stack_enabled = false;
}


/*!
	Allocates and fills in thread structure (or reuses one from the
	dead queue).

	\param threadID The ID to be assigned to the new thread. If
		  \code < 0 \endcode a fresh one is allocated.
	\param thread initialize this thread struct if nonnull
*/

static struct thread *
create_thread_struct(struct thread *inthread, const char *name,
	thread_id threadID, struct cpu_ent *cpu)
{
	struct thread *thread;
	cpu_status state;
	char temp[64];

	if (inthread == NULL) {
		// try to recycle one from the dead queue first
		state = disable_interrupts();
		GRAB_THREAD_LOCK();
		thread = thread_dequeue(&dead_q);
		RELEASE_THREAD_LOCK();
		restore_interrupts(state);

		// if not, create a new one
		if (thread == NULL) {
			thread = (struct thread *)malloc(sizeof(struct thread));
			if (thread == NULL)
				return NULL;
		}
	} else {
		thread = inthread;
	}

	if (name != NULL)
		strlcpy(thread->name, name, B_OS_NAME_LENGTH);
	else
		strcpy(thread->name, "unnamed thread");

	thread->flags = 0;
	thread->id = threadID >= 0 ? threadID : allocate_thread_id();
	thread->team = NULL;
	thread->cpu = cpu;
	thread->sem.blocking = -1;
	thread->condition_variable_entry = NULL;
	thread->fault_handler = 0;
	thread->page_faults_allowed = 1;
	thread->kernel_stack_area = -1;
	thread->kernel_stack_base = 0;
	thread->user_stack_area = -1;
	thread->user_stack_base = 0;
	thread->user_local_storage = 0;
	thread->kernel_errno = 0;
	thread->team_next = NULL;
	thread->queue_next = NULL;
	thread->priority = thread->next_priority = -1;
	thread->args1 = NULL;  thread->args2 = NULL;
	thread->alarm.period = 0;
	reset_signals(thread);
	thread->in_kernel = true;
	thread->was_yielded = false;
	thread->user_time = 0;
	thread->kernel_time = 0;
	thread->last_time = 0;
	thread->exit.status = 0;
	thread->exit.reason = 0;
	thread->exit.signal = 0;
	list_init(&thread->exit.waiters);
	thread->select_infos = NULL;

	sprintf(temp, "thread_%lx_retcode_sem", thread->id);
	thread->exit.sem = create_sem(0, temp);
	if (thread->exit.sem < B_OK)
		goto err1;

	sprintf(temp, "%s send", thread->name);
	thread->msg.write_sem = create_sem(1, temp);
	if (thread->msg.write_sem < B_OK)
		goto err2;

	sprintf(temp, "%s receive", thread->name);
	thread->msg.read_sem = create_sem(0, temp);
	if (thread->msg.read_sem < B_OK)
		goto err3;

	if (arch_thread_init_thread_struct(thread) < B_OK)
		goto err4;

	return thread;

err4:
	delete_sem(thread->msg.read_sem);
err3:
	delete_sem(thread->msg.write_sem);
err2:
	delete_sem(thread->exit.sem);
err1:
	// ToDo: put them in the dead queue instead?
	if (inthread == NULL)
		free(thread);
	return NULL;
}


static void
delete_thread_struct(struct thread *thread)
{
	delete_sem(thread->exit.sem);
	delete_sem(thread->msg.write_sem);
	delete_sem(thread->msg.read_sem);

	// ToDo: put them in the dead queue instead?
	free(thread);
}


/*! This function gets run by a new thread before anything else */
static void
thread_kthread_entry(void)
{
	struct thread *thread = thread_get_current_thread();

	// simulates the thread spinlock release that would occur if the thread had been
	// rescheded from. The resched didn't happen because the thread is new.
	RELEASE_THREAD_LOCK();

	// start tracking time
	thread->last_time = system_time();

	enable_interrupts(); // this essentially simulates a return-from-interrupt
}


static void
thread_kthread_exit(void)
{
	struct thread *thread = thread_get_current_thread();

	thread->exit.reason = THREAD_RETURN_EXIT;
	thread_exit();
}


/*!
	Initializes the thread and jumps to its userspace entry point.
	This function is called at creation time of every user thread,
	but not for a team's main thread.
*/
static int
_create_user_thread_kentry(void)
{
	struct thread *thread = thread_get_current_thread();

	// a signal may have been delivered here
	thread_at_kernel_exit();

	// jump to the entry point in user space
	arch_thread_enter_userspace(thread, (addr_t)thread->entry,
		thread->args1, thread->args2);

	// only get here if the above call fails
	return 0;
}


/*! Initializes the thread and calls it kernel space entry point. */
static int
_create_kernel_thread_kentry(void)
{
	struct thread *thread = thread_get_current_thread();
	int (*func)(void *args) = (int (*)(void *))thread->entry;

	// call the entry function with the appropriate args
	return func(thread->args1);
}


/*!
	Creates a new thread in the team with the specified team ID.

	\param threadID The ID to be assigned to the new thread. If
		  \code < 0 \endcode a fresh one is allocated.
*/
static thread_id
create_thread(const char *name, team_id teamID, thread_entry_func entry,
	void *args1, void *args2, int32 priority, bool kernel, thread_id threadID)
{
	struct thread *thread, *currentThread;
	struct team *team;
	cpu_status state;
	char stack_name[B_OS_NAME_LENGTH];
	status_t status;
	bool abort = false;
	bool debugNewThread = false;

	TRACE(("create_thread(%s, id = %ld, %s)\n", name, threadID,
		kernel ? "kernel" : "user"));

	thread = create_thread_struct(NULL, name, threadID, NULL);
	if (thread == NULL)
		return B_NO_MEMORY;

	thread->priority = priority == -1 ? B_NORMAL_PRIORITY : priority;
	thread->next_priority = thread->priority;
	// ToDo: this could be dangerous in case someone calls resume_thread() on us
	thread->state = B_THREAD_SUSPENDED;
	thread->next_state = B_THREAD_SUSPENDED;

	// init debug structure
	clear_thread_debug_info(&thread->debug_info, false);

	snprintf(stack_name, B_OS_NAME_LENGTH, "%s_%lx_kstack", name, thread->id);
	thread->kernel_stack_area = create_area(stack_name,
		(void **)&thread->kernel_stack_base, B_ANY_KERNEL_ADDRESS,
		KERNEL_STACK_SIZE, B_FULL_LOCK,
		B_KERNEL_READ_AREA | B_KERNEL_WRITE_AREA | B_KERNEL_STACK_AREA);

	if (thread->kernel_stack_area < 0) {
		// we're not yet part of a team, so we can just bail out
		status = thread->kernel_stack_area;

		dprintf("create_thread: error creating kernel stack: %s!\n",
			strerror(status));

		delete_thread_struct(thread);
		return status;
	}

	thread->kernel_stack_top = thread->kernel_stack_base + KERNEL_STACK_SIZE;

	state = disable_interrupts();
	GRAB_THREAD_LOCK();

	// If the new thread belongs to the same team as the current thread,
	// it may inherit some of the thread debug flags.
	currentThread = thread_get_current_thread();
	if (currentThread && currentThread->team->id == teamID) {
		// inherit all user flags...
		int32 debugFlags = currentThread->debug_info.flags
			& B_THREAD_DEBUG_USER_FLAG_MASK;

		// ... save the syscall tracing flags, unless explicitely specified
		if (!(debugFlags & B_THREAD_DEBUG_SYSCALL_TRACE_CHILD_THREADS)) {
			debugFlags &= ~(B_THREAD_DEBUG_PRE_SYSCALL
				| B_THREAD_DEBUG_POST_SYSCALL);
		}

		thread->debug_info.flags = debugFlags;

		// stop the new thread, if desired
		debugNewThread = debugFlags & B_THREAD_DEBUG_STOP_CHILD_THREADS;
	}

	// insert into global list
	hash_insert(sThreadHash, thread);
	sUsedThreads++;
	RELEASE_THREAD_LOCK();

	GRAB_TEAM_LOCK();
	// look at the team, make sure it's not being deleted
	team = team_get_team_struct_locked(teamID);
	if (team != NULL && team->state != TEAM_STATE_DEATH) {
		// Debug the new thread, if the parent thread required that (see above),
		// or the respective global team debug flag is set. But only, if a
		// debugger is installed for the team.
		debugNewThread |= (atomic_get(&team->debug_info.flags)
			& B_TEAM_DEBUG_STOP_NEW_THREADS);
		if (debugNewThread
			&& (atomic_get(&team->debug_info.flags)
				& B_TEAM_DEBUG_DEBUGGER_INSTALLED)) {
			thread->debug_info.flags |= B_THREAD_DEBUG_STOP;
		}

		insert_thread_into_team(team, thread);
	} else
		abort = true;

	RELEASE_TEAM_LOCK();
	if (abort) {
		GRAB_THREAD_LOCK();
		hash_remove(sThreadHash, thread);
		RELEASE_THREAD_LOCK();
	}
	restore_interrupts(state);
	if (abort) {
		delete_area(thread->kernel_stack_area);
		delete_thread_struct(thread);
		return B_BAD_TEAM_ID;
	}

	thread->args1 = args1;
	thread->args2 = args2;
	thread->entry = entry;
	status = thread->id;

	if (kernel) {
		// this sets up an initial kthread stack that runs the entry

		// Note: whatever function wants to set up a user stack later for this
		// thread must initialize the TLS for it
		arch_thread_init_kthread_stack(thread, &_create_kernel_thread_kentry,
			&thread_kthread_entry, &thread_kthread_exit);
	} else {
		// create user stack

		// the stack will be between USER_STACK_REGION and the main thread stack area
		// (the user stack of the main thread is created in team_create_team())
		thread->user_stack_base = USER_STACK_REGION;
		thread->user_stack_size = USER_STACK_SIZE;

		snprintf(stack_name, B_OS_NAME_LENGTH, "%s_%lx_stack", name, thread->id);
		thread->user_stack_area = create_area_etc(team, stack_name,
				(void **)&thread->user_stack_base, B_BASE_ADDRESS,
				thread->user_stack_size + TLS_SIZE, B_NO_LOCK,
				B_READ_AREA | B_WRITE_AREA | B_STACK_AREA);
		if (thread->user_stack_area < B_OK
			|| arch_thread_init_tls(thread) < B_OK) {
			// great, we have a fully running thread without a (usable) stack
			dprintf("create_thread: unable to create proper user stack!\n");
			status = thread->user_stack_area;
			kill_thread(thread->id);
		}

		user_debug_update_new_thread_flags(thread->id);

		// copy the user entry over to the args field in the thread struct
		// the function this will call will immediately switch the thread into
		// user space.
		arch_thread_init_kthread_stack(thread, &_create_user_thread_kentry,
			&thread_kthread_entry, &thread_kthread_exit);
	}

	return status;
}


/*!
	Finds a free death stack for us and allocates it.
	Must be called with interrupts enabled.
*/
static uint32
get_death_stack(void)
{
	cpu_status state;
	uint32 bit;
	int32 i;

	acquire_sem(sDeathStackSem);

	// grab the death stack and thread locks, find a free spot and release

	state = disable_interrupts();

	acquire_spinlock(&sDeathStackLock);
	GRAB_THREAD_LOCK();

	bit = sDeathStackBitmap;
	bit = (~bit) & ~((~bit) - 1);
	sDeathStackBitmap |= bit;

	RELEASE_THREAD_LOCK();
	release_spinlock(&sDeathStackLock);

	restore_interrupts(state);

	// sanity checks
	if (!bit)
		panic("get_death_stack: couldn't find free stack!\n");

	if (bit & (bit - 1))
		panic("get_death_stack: impossible bitmap result!\n");

	// bit to number
	for (i = -1; bit; i++) {
		bit >>= 1;
	}

	TRACE(("get_death_stack: returning %#lx\n", sDeathStacks[i].address));

	return (uint32)i;
}


/*!	Returns the thread's death stack to the pool.
	Interrupts must be disabled and the sDeathStackLock be held.
*/
static void
put_death_stack(uint32 index)
{
	TRACE(("put_death_stack...: passed %lu\n", index));

	if (index >= sNumDeathStacks)
		panic("put_death_stack: passed invalid stack index %ld\n", index);

	if (!(sDeathStackBitmap & (1 << index)))
		panic("put_death_stack: passed invalid stack index %ld\n", index);

	GRAB_THREAD_LOCK();
	sDeathStackBitmap &= ~(1 << index);
	RELEASE_THREAD_LOCK();

	release_sem_etc(sDeathStackSem, 1, B_DO_NOT_RESCHEDULE);
		// we must not hold the thread lock when releasing a semaphore
}


static void
thread_exit2(void *_args)
{
	struct thread_exit_args args;

	// copy the arguments over, since the source is probably on the kernel
	// stack we're about to delete
	memcpy(&args, _args, sizeof(struct thread_exit_args));

	// we can't let the interrupts disabled at this point
	enable_interrupts();

	TRACE(("thread_exit2, running on death stack %#lx\n", args.death_stack));

	// delete the old kernel stack area
	TRACE(("thread_exit2: deleting old kernel stack id %ld for thread %ld\n",
		args.old_kernel_stack, args.thread->id));

	delete_area(args.old_kernel_stack);

	// remove this thread from all of the global lists
	TRACE(("thread_exit2: removing thread %ld from global lists\n",
		args.thread->id));

	disable_interrupts();
	GRAB_TEAM_LOCK();

	remove_thread_from_team(team_get_kernel_team(), args.thread);

	RELEASE_TEAM_LOCK();
	enable_interrupts();
		// needed for the debugger notification below

	TRACE(("thread_exit2: done removing thread from lists\n"));

	if (args.death_sem >= 0)
		release_sem_etc(args.death_sem, 1, B_DO_NOT_RESCHEDULE);

	// notify the debugger
	if (args.original_team_id >= 0
		&& args.original_team_id != team_get_kernel_team_id()) {
		user_debug_thread_deleted(args.original_team_id, args.thread->id);
	}

	disable_interrupts();

	// Set the next state to be gone: this will cause the thread structure
	// to be returned to a ready pool upon reschedule.
	// Note, we need to have disabled interrupts at this point, or else
	// we could get rescheduled too early.
	args.thread->next_state = THREAD_STATE_FREE_ON_RESCHED;

	// return the death stack and reschedule one last time

	// Note that we need to hold sDeathStackLock until we've got the thread
	// lock. Otherwise someone else might grab our stack in the meantime.
	acquire_spinlock(&sDeathStackLock);
	put_death_stack(args.death_stack);

	GRAB_THREAD_LOCK();
	release_spinlock(&sDeathStackLock);

	scheduler_reschedule();
		// requires thread lock to be held

	// never get to here
	panic("thread_exit2: made it where it shouldn't have!\n");
}


/*!
	Fills the thread_info structure with information from the specified
	thread.
	The thread lock must be held when called.
*/
static void
fill_thread_info(struct thread *thread, thread_info *info, size_t size)
{
	info->thread = thread->id;
	info->team = thread->team->id;

	strlcpy(info->name, thread->name, B_OS_NAME_LENGTH);

	if (thread->state == B_THREAD_WAITING) {
		if (thread->sem.blocking == sSnoozeSem)
			info->state = B_THREAD_ASLEEP;
		else if (thread->sem.blocking == thread->msg.read_sem)
			info->state = B_THREAD_RECEIVING;
		else
			info->state = B_THREAD_WAITING;
	} else
		info->state = (thread_state)thread->state;

	info->priority = thread->priority;
	info->sem = thread->sem.blocking;
	info->user_time = thread->user_time;
	info->kernel_time = thread->kernel_time;
	info->stack_base = (void *)thread->user_stack_base;
	info->stack_end = (void *)(thread->user_stack_base
		+ thread->user_stack_size);
}


static status_t
send_data_etc(thread_id id, int32 code, const void *buffer,
	size_t bufferSize, int32 flags)
{
	struct thread *target;
	sem_id cachedSem;
	cpu_status state;
	status_t status;
	cbuf *data;

	state = disable_interrupts();
	GRAB_THREAD_LOCK();
	target = thread_get_thread_struct_locked(id);
	if (!target) {
		RELEASE_THREAD_LOCK();
		restore_interrupts(state);
		return B_BAD_THREAD_ID;
	}
	cachedSem = target->msg.write_sem;
	RELEASE_THREAD_LOCK();
	restore_interrupts(state);

	if (bufferSize > THREAD_MAX_MESSAGE_SIZE)
		return B_NO_MEMORY;

	status = acquire_sem_etc(cachedSem, 1, flags, 0);
	if (status == B_INTERRUPTED) {
		// We got interrupted by a signal
		return status;
	}
	if (status != B_OK) {
		// Any other acquisition problems may be due to thread deletion
		return B_BAD_THREAD_ID;
	}

	if (bufferSize > 0) {
		data = cbuf_get_chain(bufferSize);
		if (data == NULL)
			return B_NO_MEMORY;
		status = cbuf_user_memcpy_to_chain(data, 0, buffer, bufferSize);
		if (status < B_OK) {
			cbuf_free_chain(data);
			return B_NO_MEMORY;
		}
	} else
		data = NULL;

	state = disable_interrupts();
	GRAB_THREAD_LOCK();

	// The target thread could have been deleted at this point
	target = thread_get_thread_struct_locked(id);
	if (target == NULL) {
		RELEASE_THREAD_LOCK();
		restore_interrupts(state);
		cbuf_free_chain(data);
		return B_BAD_THREAD_ID;
	}

	// Save message informations
	target->msg.sender = thread_get_current_thread()->id;
	target->msg.code = code;
	target->msg.size = bufferSize;
	target->msg.buffer = data;
	cachedSem = target->msg.read_sem;

	RELEASE_THREAD_LOCK();
	restore_interrupts(state);

	release_sem(cachedSem);
	return B_OK;
}


static int32
receive_data_etc(thread_id *_sender, void *buffer, size_t bufferSize,
	int32 flags)
{
	struct thread *thread = thread_get_current_thread();
	status_t status;
	size_t size;
	int32 code;

	status = acquire_sem_etc(thread->msg.read_sem, 1, flags, 0);
	if (status < B_OK) {
		// Actually, we're not supposed to return error codes
		// but since the only reason this can fail is that we
		// were killed, it's probably okay to do so (but also
		// meaningless).
		return status;
	}

	if (buffer != NULL && bufferSize != 0) {
		size = min_c(bufferSize, thread->msg.size);
		status = cbuf_user_memcpy_from_chain(buffer, thread->msg.buffer,
			0, size);
		if (status < B_OK) {
			cbuf_free_chain(thread->msg.buffer);
			release_sem(thread->msg.write_sem);
			return status;
		}
	}

	*_sender = thread->msg.sender;
	code = thread->msg.code;

	cbuf_free_chain(thread->msg.buffer);
	release_sem(thread->msg.write_sem);

	return code;
}


//	#pragma mark - debugger calls


static int
make_thread_unreal(int argc, char **argv)
{
	struct thread *thread;
	struct hash_iterator i;
	int32 id = -1;

	if (argc > 2) {
		kprintf("usage: unreal [id]\n");
		return 0;
	}

	if (argc > 1)
		id = strtoul(argv[1], NULL, 0);

	hash_open(sThreadHash, &i);

	while ((thread = (struct thread*)hash_next(sThreadHash, &i)) != NULL) {
		if (id != -1 && thread->id != id)
			continue;

		if (thread->priority > B_DISPLAY_PRIORITY) {
			thread->priority = thread->next_priority = B_NORMAL_PRIORITY;
			kprintf("thread %ld made unreal\n", thread->id);
		}
	}

	hash_close(sThreadHash, &i, false);
	return 0;
}


static int
set_thread_prio(int argc, char **argv)
{
	struct thread *thread;
	struct hash_iterator i;
	int32 id;
	int32 prio;

	if (argc > 3 || argc < 2) {
		kprintf("usage: priority <priority> [thread-id]\n");
		return 0;
	}

	prio = strtoul(argv[1], NULL, 0);
	if (prio > B_MAX_PRIORITY)
		prio = B_MAX_PRIORITY;
	if (prio < B_MIN_PRIORITY)
		prio = B_MIN_PRIORITY;

	if (argc > 2)
		id = strtoul(argv[2], NULL, 0);
	else
		id = thread_get_current_thread()->id;

	hash_open(sThreadHash, &i);

	while ((thread = (struct thread*)hash_next(sThreadHash, &i)) != NULL) {
		if (thread->id != id)
			continue;
		thread->priority = thread->next_priority = prio;
		kprintf("thread %ld set to priority %ld\n", id, prio);
		break;
	}
	if (!thread)
		kprintf("thread %ld (%#lx) not found\n", id, id);

	hash_close(sThreadHash, &i, false);
	return 0;
}


static int
make_thread_suspended(int argc, char **argv)
{
	struct thread *thread;
	struct hash_iterator i;
	int32 id;

	if (argc > 2) {
		kprintf("usage: suspend [thread-id]\n");
		return 0;
	}

	if (argc == 1)
		id = thread_get_current_thread()->id;
	else
		id = strtoul(argv[1], NULL, 0);

	hash_open(sThreadHash, &i);

	while ((thread = (struct thread*)hash_next(sThreadHash, &i)) != NULL) {
		if (thread->id != id)
			continue;

		thread->state = thread->next_state = B_THREAD_SUSPENDED;
		kprintf("thread %ld suspended\n", id);
		break;
	}
	if (!thread)
		kprintf("thread %ld (%#lx) not found\n", id, id);

	hash_close(sThreadHash, &i, false);
	return 0;
}


static int
make_thread_resumed(int argc, char **argv)
{
	struct thread *thread;
	struct hash_iterator i;
	int32 id;

	if (argc != 2) {
		kprintf("usage: resume <thread-id>\n");
		return 0;
	}

	// force user to enter a thread id, as using
	// the current thread is usually not intended
	id = strtoul(argv[1], NULL, 0);

	hash_open(sThreadHash, &i);

	while ((thread = (struct thread*)hash_next(sThreadHash, &i)) != NULL) {
		if (thread->id != id)
			continue;

		if (thread->state == B_THREAD_SUSPENDED) {
			thread->state = thread->next_state = B_THREAD_READY;
			scheduler_enqueue_in_run_queue(thread);
			kprintf("thread %ld resumed\n", thread->id);
		}
		break;
	}
	if (!thread)
		kprintf("thread %ld (%#lx) not found\n", id, id);

	hash_close(sThreadHash, &i, false);
	return 0;
}


static int
drop_into_debugger(int argc, char **argv)
{
	status_t err;
	int32 id;

	if (argc > 2) {
		kprintf("usage: drop [thread-id]\n");
		return 0;
	}

	if (argc == 1)
		id = thread_get_current_thread()->id;
	else
		id = strtoul(argv[1], NULL, 0);

	err = _user_debug_thread(id);
	if (err)
		kprintf("drop failed\n");
	else
		kprintf("thread %ld dropped into user debugger\n", id);

	return 0;
}


static const char *
state_to_text(struct thread *thread, int32 state)
{
	switch (state) {
		case B_THREAD_READY:
			return "ready";

		case B_THREAD_RUNNING:
			return "running";

		case B_THREAD_WAITING:
			if (thread->sem.blocking == sSnoozeSem)
				return "zzz";
			if (thread->sem.blocking == thread->msg.read_sem)
				return "receive";

			return "waiting";

		case B_THREAD_SUSPENDED:
			return "suspended";

		case THREAD_STATE_FREE_ON_RESCHED:
			return "death";

		default:
			return "UNKNOWN";
	}
}


static void
_dump_thread_info(struct thread *thread)
{
	struct death_entry *death = NULL;

	kprintf("THREAD: %p\n", thread);
	kprintf("id:                 %ld (%#lx)\n", thread->id, thread->id);
	kprintf("name:               \"%s\"\n", thread->name);
	kprintf("all_next:           %p\nteam_next:          %p\nq_next:             %p\n",
		thread->all_next, thread->team_next, thread->queue_next);
	kprintf("priority:           %ld (next %ld)\n", thread->priority, thread->next_priority);
	kprintf("state:              %s\n", state_to_text(thread, thread->state));
	kprintf("next_state:         %s\n", state_to_text(thread, thread->next_state));
	kprintf("cpu:                %p ", thread->cpu);
	if (thread->cpu)
		kprintf("(%d)\n", thread->cpu->cpu_num);
	else
		kprintf("\n");
	kprintf("sig_pending:        %#lx\n", thread->sig_pending);
	kprintf("in_kernel:          %d\n", thread->in_kernel);
	kprintf("  sem.blocking:     %ld\n", thread->sem.blocking);
	kprintf("  sem.count:        %ld\n", thread->sem.count);
	kprintf("  sem.acquire_status: %#lx\n", thread->sem.acquire_status);
	kprintf("  sem.flags:        %#lx\n", thread->sem.flags);

	kprintf("condition variables:");
	PrivateConditionVariableEntry* entry = thread->condition_variable_entry;
	while (entry != NULL) {
		kprintf(" %p", entry->Variable());
		entry = entry->ThreadNext();
	}
	kprintf("\n");

	kprintf("fault_handler:      %p\n", (void *)thread->fault_handler);
	kprintf("args:               %p %p\n", thread->args1, thread->args2);
	kprintf("entry:              %p\n", (void *)thread->entry);
	kprintf("team:               %p, \"%s\"\n", thread->team, thread->team->name);
	kprintf("  exit.sem:         %ld\n", thread->exit.sem);
	kprintf("  exit.status:      %#lx (%s)\n", thread->exit.status, strerror(thread->exit.status));
	kprintf("  exit.reason:      %#x\n", thread->exit.reason);
	kprintf("  exit.signal:      %#x\n", thread->exit.signal);
	kprintf("  exit.waiters:\n");
	while ((death = (struct death_entry*)list_get_next_item(
			&thread->exit.waiters, death)) != NULL) {
		kprintf("\t%p (group %ld, thread %ld)\n", death, death->group_id, death->thread);
	}

	kprintf("kernel_stack_area:  %ld\n", thread->kernel_stack_area);
	kprintf("kernel_stack_base:  %p\n", (void *)thread->kernel_stack_base);
	kprintf("user_stack_area:    %ld\n", thread->user_stack_area);
	kprintf("user_stack_base:    %p\n", (void *)thread->user_stack_base);
	kprintf("user_local_storage: %p\n", (void *)thread->user_local_storage);
	kprintf("kernel_errno:       %#x (%s)\n", thread->kernel_errno,
		strerror(thread->kernel_errno));
	kprintf("kernel_time:        %Ld\n", thread->kernel_time);
	kprintf("user_time:          %Ld\n", thread->user_time);
	kprintf("flags:              0x%lx\n", thread->flags);
	kprintf("architecture dependant section:\n");
	arch_thread_dump_info(&thread->arch_info);
}


static int
dump_thread_info(int argc, char **argv)
{
	const char *name = NULL;
	struct thread *thread;
	int32 id = -1;
	struct hash_iterator i;
	bool found = false;

	if (argc > 2) {
		kprintf("usage: thread [id/address/name]\n");
		return 0;
	}

	if (argc == 1) {
		_dump_thread_info(thread_get_current_thread());
		return 0;
	} else {
		name = argv[1];
		id = strtoul(argv[1], NULL, 0);

		if (IS_KERNEL_ADDRESS(id)) {
			// semi-hack
			_dump_thread_info((struct thread *)id);
			return 0;
		}
	}

	// walk through the thread list, trying to match name or id
	hash_open(sThreadHash, &i);
	while ((thread = (struct thread*)hash_next(sThreadHash, &i)) != NULL) {
		if ((name != NULL && !strcmp(name, thread->name)) || thread->id == id) {
			_dump_thread_info(thread);
			found = true;
			break;
		}
	}
	hash_close(sThreadHash, &i, false);

	if (!found)
		kprintf("thread \"%s\" (%ld) doesn't exist!\n", argv[1], id);
	return 0;
}


static int
dump_thread_list(int argc, char **argv)
{
	struct thread *thread;
	struct hash_iterator i;
	bool realTimeOnly = false;
	int32 requiredState = 0;
	team_id team = -1;
	sem_id sem = -1;

	if (!strcmp(argv[0], "realtime"))
		realTimeOnly = true;
	else if (!strcmp(argv[0], "ready"))
		requiredState = B_THREAD_READY;
	else if (!strcmp(argv[0], "running"))
		requiredState = B_THREAD_RUNNING;
	else if (!strcmp(argv[0], "waiting")) {
		requiredState = B_THREAD_WAITING;

		if (argc > 1) {
			sem = strtoul(argv[1], NULL, 0);
			if (sem == 0)
				kprintf("ignoring invalid semaphore argument.\n");
		}
	} else if (argc > 1) {
		team = strtoul(argv[1], NULL, 0);
		if (team == 0)
			kprintf("ignoring invalid team argument.\n");
	}

	kprintf("thread         id  state        sem/cv cpu pri  stack      team  "
		"name\n");

	hash_open(sThreadHash, &i);
	while ((thread = (struct thread*)hash_next(sThreadHash, &i)) != NULL) {
		// filter out threads not matching the search criteria
		if ((requiredState && thread->state != requiredState)
			|| (sem > 0 && thread->sem.blocking != sem)
			|| (team > 0 && thread->team->id != team)
			|| (realTimeOnly && thread->priority < B_REAL_TIME_DISPLAY_PRIORITY))
			continue;

		kprintf("%p %6ld  %-9s", thread, thread->id, state_to_text(thread,
			thread->state));

		// does it block on a semaphore or a condition variable?
		if (thread->state == B_THREAD_WAITING) {
			if (thread->condition_variable_entry)
				kprintf("%p  ", thread->condition_variable_entry->Variable());
			else
				kprintf("%10ld  ", thread->sem.blocking);
		} else
			kprintf("      -     ");

		// on which CPU does it run?
		if (thread->cpu)
			kprintf("%2d", thread->cpu->cpu_num);
		else
			kprintf(" -");

		kprintf("%4ld  %p%5ld  %s\n", thread->priority,
			(void *)thread->kernel_stack_base, thread->team->id,
			thread->name != NULL ? thread->name : "<NULL>");
	}
	hash_close(sThreadHash, &i, false);
	return 0;
}


//	#pragma mark - private kernel API


void
thread_exit(void)
{
	cpu_status state;
	struct thread *thread = thread_get_current_thread();
	struct process_group *freeGroup = NULL;
	struct team *team = thread->team;
	thread_id parentID = -1;
	bool deleteTeam = false;
	sem_id cachedDeathSem = -1;
	status_t status;
	struct thread_debug_info debugInfo;
	team_id teamID = team->id;

	TRACE(("thread %ld exiting %s w/return code %#lx\n", thread->id,
		thread->exit.reason == THREAD_RETURN_INTERRUPTED
			? "due to signal" : "normally", thread->exit.status));

	if (!are_interrupts_enabled())
		panic("thread_exit() called with interrupts disabled!\n");

	// boost our priority to get this over with
	thread->priority = thread->next_priority = B_URGENT_DISPLAY_PRIORITY;

	// Cancel previously installed alarm timer, if any
	cancel_timer(&thread->alarm);

	// delete the user stack area first, we won't need it anymore
	if (team->address_space != NULL && thread->user_stack_area >= 0) {
		area_id area = thread->user_stack_area;
		thread->user_stack_area = -1;
		delete_area_etc(team, area);
	}

	struct job_control_entry *death = NULL;
	struct death_entry* threadDeathEntry = NULL;

	if (team != team_get_kernel_team()) {
		if (team->main_thread == thread) {
			// this was the main thread in this team, so we will delete that as well
			deleteTeam = true;
		} else
			threadDeathEntry = (death_entry*)malloc(sizeof(death_entry));

		// remove this thread from the current team and add it to the kernel
		// put the thread into the kernel team until it dies
		state = disable_interrupts();
		GRAB_TEAM_LOCK();
		GRAB_THREAD_LOCK();
			// removing the thread and putting its death entry to the parent
			// team needs to be an atomic operation

		// remember how long this thread lasted
		team->dead_threads_kernel_time += thread->kernel_time;
		team->dead_threads_user_time += thread->user_time;

		remove_thread_from_team(team, thread);
		insert_thread_into_team(team_get_kernel_team(), thread);

		cachedDeathSem = team->death_sem;

		if (deleteTeam) {
			struct team *parent = team->parent;

			// remember who our parent was so we can send a signal
			parentID = parent->id;

			// Set the team job control state to "dead" and detach the job
			// control entry from our team struct.
			team_set_job_control_state(team, JOB_CONTROL_STATE_DEAD, 0, true);
			death = team->job_control_entry;
			team->job_control_entry = NULL;

			if (death != NULL) {
				death->team = NULL;
				death->group_id = team->group_id;
				death->thread = thread->id;
				death->status = thread->exit.status;
				death->reason = thread->exit.reason;
				death->signal = thread->exit.signal;

				// team_set_job_control_state() already moved our entry
				// into the parent's list. We just check the soft limit of
				// death entries.
				if (parent->dead_children->count > MAX_DEAD_CHILDREN) {
					death = parent->dead_children->entries.RemoveHead();
					parent->dead_children->count--;
				} else
					death = NULL;

				RELEASE_THREAD_LOCK();
			} else
				RELEASE_THREAD_LOCK();

			team_remove_team(team, &freeGroup);

			send_signal_etc(parentID, SIGCHLD,
				SIGNAL_FLAG_TEAMS_LOCKED | B_DO_NOT_RESCHEDULE);
		} else {
			// The thread is not the main thread. We store a thread death
			// entry for it, unless someone is already waiting it.
			if (threadDeathEntry != NULL
				&& list_is_empty(&thread->exit.waiters)) {
				threadDeathEntry->thread = thread->id;
				threadDeathEntry->status = thread->exit.status;
				threadDeathEntry->reason = thread->exit.reason;
				threadDeathEntry->signal = thread->exit.signal;

				// add entry -- remove and old one, if we hit the limit
				list_add_item(&team->dead_threads, threadDeathEntry);
				team->dead_threads_count++;
				threadDeathEntry = NULL;

				if (team->dead_threads_count > MAX_DEAD_THREADS) {
					threadDeathEntry = (death_entry*)list_remove_head_item(
						&team->dead_threads);
					team->dead_threads_count--;
				}
			}

			RELEASE_THREAD_LOCK();
		}

		RELEASE_TEAM_LOCK();

		// swap address spaces, to make sure we're running on the kernel's pgdir
		vm_swap_address_space(vm_kernel_address_space());
		restore_interrupts(state);

		TRACE(("thread_exit: thread %ld now a kernel thread!\n", thread->id));
	}

	if (threadDeathEntry != NULL)
		free(threadDeathEntry);

	// delete the team if we're its main thread
	if (deleteTeam) {
		team_delete_process_group(freeGroup);
		team_delete_team(team);

		// we need to delete any death entry that made it to here
		if (death != NULL)
			delete death;

		cachedDeathSem = -1;
	}

	state = disable_interrupts();
	GRAB_THREAD_LOCK();

	// remove thread from hash, so it's no longer accessible
	hash_remove(sThreadHash, thread);
	sUsedThreads--;

	// Stop debugging for this thread
	debugInfo = thread->debug_info;
	clear_thread_debug_info(&thread->debug_info, true);

	// Remove the select infos. We notify them a little later.
	select_info* selectInfos = thread->select_infos;
	thread->select_infos = NULL;

	RELEASE_THREAD_LOCK();
	restore_interrupts(state);

	destroy_thread_debug_info(&debugInfo);

	// notify select infos
	select_info* info = selectInfos;
	while (info != NULL) {
		select_sync* sync = info->sync;

		notify_select_events(info, B_EVENT_INVALID);
		info = info->next;
		put_select_sync(sync);
	}

	// shutdown the thread messaging

	status = acquire_sem_etc(thread->msg.write_sem, 1, B_RELATIVE_TIMEOUT, 0);
	if (status == B_WOULD_BLOCK) {
		// there is data waiting for us, so let us eat it
		thread_id sender;

		delete_sem(thread->msg.write_sem);
			// first, let's remove all possibly waiting writers
		receive_data_etc(&sender, NULL, 0, B_RELATIVE_TIMEOUT);
	} else {
		// we probably own the semaphore here, and we're the last to do so
		delete_sem(thread->msg.write_sem);
	}
	// now we can safely remove the msg.read_sem
	delete_sem(thread->msg.read_sem);

	// fill all death entries and delete the sem that others will use to wait on us
	{
		sem_id cachedExitSem = thread->exit.sem;
		cpu_status state;

		state = disable_interrupts();
		GRAB_THREAD_LOCK();

		// make sure no one will grab this semaphore again
		thread->exit.sem = -1;

		// fill all death entries
		death_entry* entry = NULL;
		while ((entry = (struct death_entry*)list_get_next_item(
				&thread->exit.waiters, entry)) != NULL) {
			entry->status = thread->exit.status;
			entry->reason = thread->exit.reason;
			entry->signal = thread->exit.signal;
		}

		RELEASE_THREAD_LOCK();
		restore_interrupts(state);

		delete_sem(cachedExitSem);
	}

	{
		struct thread_exit_args args;

		args.thread = thread;
		args.old_kernel_stack = thread->kernel_stack_area;
		args.death_stack = get_death_stack();
		args.death_sem = cachedDeathSem;
		args.original_team_id = teamID;


		disable_interrupts();

		// set the new kernel stack officially to the death stack, it won't be
		// switched until the next function is called. This must be done now
		// before a context switch, or we'll stay on the old stack
		thread->kernel_stack_area = sDeathStacks[args.death_stack].area;
		thread->kernel_stack_base = sDeathStacks[args.death_stack].address;

		// we will continue in thread_exit2(), on the new stack
		arch_thread_switch_kstack_and_call(thread, thread->kernel_stack_base
			 + KERNEL_STACK_SIZE, thread_exit2, &args);
	}

	panic("never can get here\n");
}


struct thread *
thread_get_thread_struct(thread_id id)
{
	struct thread *thread;
	cpu_status state;

	state = disable_interrupts();
	GRAB_THREAD_LOCK();

	thread = thread_get_thread_struct_locked(id);

	RELEASE_THREAD_LOCK();
	restore_interrupts(state);

	return thread;
}


struct thread *
thread_get_thread_struct_locked(thread_id id)
{
	struct thread_key key;

	key.id = id;

	return (struct thread*)hash_lookup(sThreadHash, &key);
}


/*!
	Called in the interrupt handler code when a thread enters
	the kernel for any reason.
	Only tracks time for now.
	Interrupts are disabled.
*/
void
thread_at_kernel_entry(bigtime_t now)
{
	struct thread *thread = thread_get_current_thread();

	TRACE(("thread_at_kernel_entry: entry thread %ld\n", thread->id));

	// track user time
	thread->user_time += now - thread->last_time;
	thread->last_time = now;

	thread->in_kernel = true;
}


/*!
	Called whenever a thread exits kernel space to user space.
	Tracks time, handles signals, ...
*/
void
thread_at_kernel_exit(void)
{
	struct thread *thread = thread_get_current_thread();
	cpu_status state;
	bigtime_t now;

	TRACE(("thread_at_kernel_exit: exit thread %ld\n", thread->id));

	if (handle_signals(thread)) {
		state = disable_interrupts();
		GRAB_THREAD_LOCK();

		// was: smp_send_broadcast_ici(SMP_MSG_RESCHEDULE, 0, 0, 0, NULL, SMP_MSG_FLAG_SYNC);
		scheduler_reschedule();

		RELEASE_THREAD_LOCK();
	} else
		state = disable_interrupts();

	thread->in_kernel = false;

	// track kernel time
	now = system_time();
	thread->kernel_time += now - thread->last_time;
	thread->last_time = now;

	restore_interrupts(state);
}


/*!	The quick version of thread_kernel_exit(), in case no signals are pending
	and no debugging shall be done.
	Interrupts are disabled in this case.
*/
void
thread_at_kernel_exit_no_signals(void)
{
	struct thread *thread = thread_get_current_thread();

	TRACE(("thread_at_kernel_exit_no_signals: exit thread %ld\n", thread->id));

	thread->in_kernel = false;

	// track kernel time
	bigtime_t now = system_time();
	thread->kernel_time += now - thread->last_time;
	thread->last_time = now;
}


void
thread_reset_for_exec(void)
{
	struct thread *thread = thread_get_current_thread();

	cancel_timer(&thread->alarm);
	reset_signals(thread);
}


/*! Insert a thread to the tail of a queue */
void
thread_enqueue(struct thread *thread, struct thread_queue *queue)
{
	thread->queue_next = NULL;
	if (queue->head == NULL) {
		queue->head = thread;
		queue->tail = thread;
	} else {
		queue->tail->queue_next = thread;
		queue->tail = thread;
	}
}


struct thread *
thread_lookat_queue(struct thread_queue *queue)
{
	return queue->head;
}


struct thread *
thread_dequeue(struct thread_queue *queue)
{
	struct thread *thread = queue->head;

	if (thread != NULL) {
		queue->head = thread->queue_next;
		if (queue->tail == thread)
			queue->tail = NULL;
	}
	return thread;
}


struct thread *
thread_dequeue_id(struct thread_queue *q, thread_id id)
{
	struct thread *thread;
	struct thread *last = NULL;

	thread = q->head;
	while (thread != NULL) {
		if (thread->id == id) {
			if (last == NULL)
				q->head = thread->queue_next;
			else
				last->queue_next = thread->queue_next;

			if (q->tail == thread)
				q->tail = last;
			break;
		}
		last = thread;
		thread = thread->queue_next;
	}
	return thread;
}


thread_id
allocate_thread_id(void)
{
	return atomic_add(&sNextThreadID, 1);
}


thread_id
peek_next_thread_id(void)
{
	return atomic_get(&sNextThreadID);
}


void
thread_yield(void)
{
	// snooze for roughly 3 thread quantums
	snooze_etc(9000, B_SYSTEM_TIMEBASE, B_RELATIVE_TIMEOUT | B_CAN_INTERRUPT);
#if 0
	cpu_status state;

	struct thread *thread = thread_get_current_thread();
	if (thread == NULL)
		return;

	state = disable_interrupts();
	GRAB_THREAD_LOCK();

	// mark the thread as yielded, so it will not be scheduled next
	//thread->was_yielded = true;
	thread->next_priority = B_LOWEST_ACTIVE_PRIORITY;
	scheduler_reschedule();

	RELEASE_THREAD_LOCK();
	restore_interrupts(state);
#endif
}


/*!
	Kernel private thread creation function.

	\param threadID The ID to be assigned to the new thread. If
		  \code < 0 \endcode a fresh one is allocated.
*/
thread_id
spawn_kernel_thread_etc(thread_func function, const char *name, int32 priority,
	void *arg, team_id team, thread_id threadID)
{
	return create_thread(name, team, (thread_entry_func)function, arg, NULL,
		priority, true, threadID);
}


status_t
wait_for_thread_etc(thread_id id, uint32 flags, bigtime_t timeout,
	status_t *_returnCode)
{
	sem_id exitSem = B_BAD_THREAD_ID;
	struct death_entry death;
	job_control_entry* freeDeath = NULL;
	struct thread *thread;
	cpu_status state;
	status_t status = B_OK;

	if (id < B_OK)
		return B_BAD_THREAD_ID;

	// we need to resume the thread we're waiting for first

	state = disable_interrupts();
	GRAB_THREAD_LOCK();

	thread = thread_get_thread_struct_locked(id);
	if (thread != NULL) {
		// remember the semaphore we have to wait on and place our death entry
		exitSem = thread->exit.sem;
		list_add_link_to_head(&thread->exit.waiters, &death);
	}

	death_entry* threadDeathEntry = NULL;

	RELEASE_THREAD_LOCK();

	if (thread == NULL) {
		// we couldn't find this thread - maybe it's already gone, and we'll
		// find its death entry in our team
		GRAB_TEAM_LOCK();

		struct team* team = thread_get_current_thread()->team;

		// check the child death entries first (i.e. main threads of child
		// teams)
		bool deleteEntry;
		freeDeath = team_get_death_entry(team, id, &deleteEntry);
		if (freeDeath != NULL) {
			death.status = freeDeath->status;
			if (!deleteEntry)
				freeDeath = NULL;
		} else {
			// check the thread death entries of the team (non-main threads)
			while ((threadDeathEntry = (death_entry*)list_get_next_item(
					&team->dead_threads, threadDeathEntry)) != NULL) {
				if (threadDeathEntry->thread == id) {
					list_remove_item(&team->dead_threads, threadDeathEntry);
					team->dead_threads_count--;
					death.status = threadDeathEntry->status;
					break;
				}
			}

			if (threadDeathEntry == NULL)
				status = B_BAD_THREAD_ID;
		}

		RELEASE_TEAM_LOCK();
	}

	restore_interrupts(state);

	if (thread == NULL && status == B_OK) {
		// we found the thread's death entry in our team
		if (_returnCode)
			*_returnCode = death.status;

		delete freeDeath;
		free(threadDeathEntry);
		return B_OK;
	}

	// we need to wait for the death of the thread

	if (exitSem < B_OK)
		return B_BAD_THREAD_ID;

	resume_thread(id);
		// make sure we don't wait forever on a suspended thread

	status = acquire_sem_etc(exitSem, 1, flags, timeout);

	if (status == B_OK) {
		// this should never happen as the thread deletes the semaphore on exit
		panic("could acquire exit_sem for thread %ld\n", id);
	} else if (status == B_BAD_SEM_ID) {
		// this is the way the thread normally exits
		status = B_OK;

		if (_returnCode)
			*_returnCode = death.status;
	} else {
		// We were probably interrupted; we need to remove our death entry now.
		state = disable_interrupts();
		GRAB_THREAD_LOCK();

		thread = thread_get_thread_struct_locked(id);
		if (thread != NULL)
			list_remove_link(&death);

		RELEASE_THREAD_LOCK();
		restore_interrupts(state);

		// If the thread is already gone, we need to wait for its exit semaphore
		// to make sure our death entry stays valid - it won't take long
		if (thread == NULL)
			acquire_sem(exitSem);
	}

	return status;
}


status_t
select_thread(int32 id, struct select_info* info, bool kernel)
{
	InterruptsSpinLocker locker(thread_spinlock);

	// get thread
	struct thread* thread = thread_get_thread_struct_locked(id);
	if (thread == NULL)
		return B_BAD_THREAD_ID;

	// We support only B_EVENT_INVALID at the moment.
	info->selected_events &= B_EVENT_INVALID;

	// add info to list
	if (info->selected_events != 0) {
		info->next = thread->select_infos;
		thread->select_infos = info;

		// we need a sync reference
		atomic_add(&info->sync->ref_count, 1);
	}

	return B_OK;
}


status_t
deselect_thread(int32 id, struct select_info* info, bool kernel)
{
	InterruptsSpinLocker locker(thread_spinlock);

	// get thread
	struct thread* thread = thread_get_thread_struct_locked(id);
	if (thread == NULL)
		return B_BAD_THREAD_ID;

	// remove info from list
	select_info** infoLocation = &thread->select_infos;
	while (*infoLocation != NULL && *infoLocation != info)
		infoLocation = &(*infoLocation)->next;

	if (*infoLocation != info)
		return B_OK;

	*infoLocation = info->next;

	locker.Unlock();

	// surrender sync reference
	put_select_sync(info->sync);

	return B_OK;
}


int32
thread_max_threads(void)
{
	return sMaxThreads;
}


int32
thread_used_threads(void)
{
	return sUsedThreads;
}


status_t
thread_init(kernel_args *args)
{
	uint32 i;

	TRACE(("thread_init: entry\n"));

	// create the thread hash table
	sThreadHash = hash_init(15, offsetof(struct thread, all_next),
		&thread_struct_compare, &thread_struct_hash);

	// zero out the dead thread structure q
	memset(&dead_q, 0, sizeof(dead_q));

	// allocate snooze sem
	sSnoozeSem = create_sem(0, "snooze sem");
	if (sSnoozeSem < 0) {
		panic("error creating snooze sem\n");
		return sSnoozeSem;
	}

	if (arch_thread_init(args) < B_OK)
		panic("arch_thread_init() failed!\n");

	// skip all thread IDs including B_SYSTEM_TEAM, which is reserved
	sNextThreadID = B_SYSTEM_TEAM + 1;

	// create an idle thread for each cpu

	for (i = 0; i < args->num_cpus; i++) {
		struct thread *thread;
		area_info info;
		char name[64];

		sprintf(name, "idle thread %lu", i + 1);
		thread = create_thread_struct(&sIdleThreads[i], name,
			i == 0 ? team_get_kernel_team_id() : -1, &gCPU[i]);
		if (thread == NULL) {
			panic("error creating idle thread struct\n");
			return B_NO_MEMORY;
		}

		thread->team = team_get_kernel_team();
		thread->priority = thread->next_priority = B_IDLE_PRIORITY;
		thread->state = B_THREAD_RUNNING;
		thread->next_state = B_THREAD_READY;
		sprintf(name, "idle thread %lu kstack", i + 1);
		thread->kernel_stack_area = find_area(name);
		thread->entry = NULL;

		if (get_area_info(thread->kernel_stack_area, &info) != B_OK)
			panic("error finding idle kstack area\n");

		thread->kernel_stack_base = (addr_t)info.address;

		hash_insert(sThreadHash, thread);
		insert_thread_into_team(thread->team, thread);
	}
	sUsedThreads = args->num_cpus;

	// create a set of death stacks

	sNumDeathStacks = smp_get_num_cpus();
	if (sNumDeathStacks > 8 * sizeof(sDeathStackBitmap)) {
		// clamp values for really beefy machines
		sNumDeathStacks = 8 * sizeof(sDeathStackBitmap);
	}
	sDeathStackBitmap = 0;
	sDeathStacks = (struct death_stack *)malloc(sNumDeathStacks
		* sizeof(struct death_stack));
	if (sDeathStacks == NULL) {
		panic("error creating death stacks\n");
		return B_NO_MEMORY;
	}
	{
		char temp[64];

		for (i = 0; i < sNumDeathStacks; i++) {
			sprintf(temp, "death stack %lu", i);
			sDeathStacks[i].area = create_area(temp,
				(void **)&sDeathStacks[i].address, B_ANY_KERNEL_ADDRESS,
				KERNEL_STACK_SIZE, B_FULL_LOCK,
				B_KERNEL_READ_AREA | B_KERNEL_WRITE_AREA | B_KERNEL_STACK_AREA);
			if (sDeathStacks[i].area < 0) {
				panic("error creating death stacks\n");
				return sDeathStacks[i].area;
			}
			sDeathStacks[i].in_use = false;
		}
	}
	sDeathStackSem = create_sem(sNumDeathStacks, "death stack availability");

	// set up some debugger commands
	add_debugger_command("threads", &dump_thread_list, "list all threads");
	add_debugger_command("ready", &dump_thread_list, "list all ready threads");
	add_debugger_command("running", &dump_thread_list, "list all running threads");
	add_debugger_command("waiting", &dump_thread_list, "list all waiting threads (optionally for a specific semaphore)");
	add_debugger_command("realtime", &dump_thread_list, "list all realtime threads");
	add_debugger_command("thread", &dump_thread_info, "list info about a particular thread");
	add_debugger_command("unreal", &make_thread_unreal, "set realtime priority threads to normal priority");
	add_debugger_command("suspend", &make_thread_suspended, "suspend a thread");
	add_debugger_command("resume", &make_thread_resumed, "resume a thread");
	add_debugger_command("drop", &drop_into_debugger, "drop a thread into the user-debugger");
	add_debugger_command("priority", &set_thread_prio, "set a thread priority");

	return B_OK;
}


status_t
thread_preboot_init_percpu(struct kernel_args *args, int32 cpuNum)
{
	// set up the cpu pointer in the not yet initialized per-cpu idle thread
	// so that get_current_cpu and friends will work, which is crucial for
	// a lot of low level routines
	sIdleThreads[cpuNum].cpu = &gCPU[cpuNum];
	arch_thread_set_current_thread(&sIdleThreads[cpuNum]);
	return B_OK;
}

//	#pragma mark - public kernel API


void
exit_thread(status_t returnValue)
{
	struct thread *thread = thread_get_current_thread();

	thread->exit.status = returnValue;
	thread->exit.reason = THREAD_RETURN_EXIT;

	// if called from a kernel thread, we don't deliver the signal,
	// we just exit directly to keep the user space behaviour of
	// this function
	if (thread->team != team_get_kernel_team())
		send_signal_etc(thread->id, SIGKILLTHR, B_DO_NOT_RESCHEDULE);
	else
		thread_exit();
}


status_t
kill_thread(thread_id id)
{
	if (id <= 0)
		return B_BAD_VALUE;

	return send_signal(id, SIGKILLTHR);
}


status_t
send_data(thread_id thread, int32 code, const void *buffer, size_t bufferSize)
{
	return send_data_etc(thread, code, buffer, bufferSize, 0);
}


int32
receive_data(thread_id *sender, void *buffer, size_t bufferSize)
{
	return receive_data_etc(sender, buffer, bufferSize, 0);
}


bool
has_data(thread_id thread)
{
	int32 count;

	if (get_sem_count(thread_get_current_thread()->msg.read_sem,
			&count) != B_OK)
		return false;

	return count == 0 ? false : true;
}


status_t
_get_thread_info(thread_id id, thread_info *info, size_t size)
{
	status_t status = B_OK;
	struct thread *thread;
	cpu_status state;

	if (info == NULL || size != sizeof(thread_info) || id < B_OK)
		return B_BAD_VALUE;

	state = disable_interrupts();
	GRAB_THREAD_LOCK();

	thread = thread_get_thread_struct_locked(id);
	if (thread == NULL) {
		status = B_BAD_VALUE;
		goto err;
	}

	fill_thread_info(thread, info, size);

err:
	RELEASE_THREAD_LOCK();
	restore_interrupts(state);

	return status;
}


status_t
_get_next_thread_info(team_id team, int32 *_cookie, thread_info *info,
	size_t size)
{
	status_t status = B_BAD_VALUE;
	struct thread *thread = NULL;
	cpu_status state;
	int slot;
	thread_id lastThreadID;

	if (info == NULL || size != sizeof(thread_info) || team < B_OK)
		return B_BAD_VALUE;

	if (team == B_CURRENT_TEAM)
		team = team_get_current_team_id();
	else if (!team_is_valid(team))
		return B_BAD_VALUE;

	slot = *_cookie;

	state = disable_interrupts();
	GRAB_THREAD_LOCK();

	lastThreadID = peek_next_thread_id();
	if (slot >= lastThreadID)
		goto err;

	while (slot < lastThreadID
		&& (!(thread = thread_get_thread_struct_locked(slot))
			|| thread->team->id != team))
		slot++;

	if (thread != NULL && thread->team->id == team) {
		fill_thread_info(thread, info, size);

		*_cookie = slot + 1;
		status = B_OK;
	}

err:
	RELEASE_THREAD_LOCK();
	restore_interrupts(state);

	return status;
}


thread_id
find_thread(const char *name)
{
	struct hash_iterator iterator;
	struct thread *thread;
	cpu_status state;

	if (name == NULL)
		return thread_get_current_thread_id();

	state = disable_interrupts();
	GRAB_THREAD_LOCK();

	// ToDo: this might not be in the same order as find_thread() in BeOS
	//		which could be theoretically problematic.
	// ToDo: scanning the whole list with the thread lock held isn't exactly
	//		cheap either - although this function is probably used very rarely.

	hash_open(sThreadHash, &iterator);
	while ((thread = (struct thread*)hash_next(sThreadHash, &iterator))
			!= NULL) {
		// Search through hash
		if (thread->name != NULL && !strcmp(thread->name, name)) {
			thread_id id = thread->id;

			RELEASE_THREAD_LOCK();
			restore_interrupts(state);
			return id;
		}
	}

	RELEASE_THREAD_LOCK();
	restore_interrupts(state);

	return B_NAME_NOT_FOUND;
}


status_t
rename_thread(thread_id id, const char *name)
{
	struct thread *thread = thread_get_current_thread();
	status_t status = B_BAD_THREAD_ID;
	cpu_status state;

	if (name == NULL)
		return B_BAD_VALUE;

	state = disable_interrupts();
	GRAB_THREAD_LOCK();

	if (thread->id != id)
		thread = thread_get_thread_struct_locked(id);

	if (thread != NULL) {
		if (thread->team == thread_get_current_thread()->team) {
			strlcpy(thread->name, name, B_OS_NAME_LENGTH);
			status = B_OK;
		} else
			status = B_NOT_ALLOWED;
	}

	RELEASE_THREAD_LOCK();
	restore_interrupts(state);

	return status;
}


status_t
set_thread_priority(thread_id id, int32 priority)
{
	struct thread *thread;
	int32 oldPriority;

	// make sure the passed in priority is within bounds
	if (priority > B_MAX_PRIORITY)
		priority = B_MAX_PRIORITY;
	if (priority < B_MIN_PRIORITY)
		priority = B_MIN_PRIORITY;

	thread = thread_get_current_thread();
	if (thread->id == id) {
		// it's ourself, so we know we aren't in the run queue, and we can manipulate
		// our structure directly
		oldPriority = thread->priority;
			// note that this might not return the correct value if we are preempted
			// here, and another thread changes our priority before the next line is
			// executed
		thread->priority = thread->next_priority = priority;
	} else {
		cpu_status state = disable_interrupts();
		GRAB_THREAD_LOCK();

		thread = thread_get_thread_struct_locked(id);
		if (thread) {
			oldPriority = thread->priority;
			thread->next_priority = priority;
			if (thread->state == B_THREAD_READY && thread->priority != priority) {
				// if the thread is in the run queue, we reinsert it at a new position
				scheduler_remove_from_run_queue(thread);
				thread->priority = priority;
				scheduler_enqueue_in_run_queue(thread);
			} else
				thread->priority = priority;
		} else
			oldPriority = B_BAD_THREAD_ID;

		RELEASE_THREAD_LOCK();
		restore_interrupts(state);
	}

	return oldPriority;
}


status_t
snooze_etc(bigtime_t timeout, int timebase, uint32 flags)
{
	status_t status;

	if (timebase != B_SYSTEM_TIMEBASE)
		return B_BAD_VALUE;

	status = acquire_sem_etc(sSnoozeSem, 1, flags, timeout);
	if (status == B_TIMED_OUT || status == B_WOULD_BLOCK)
		return B_OK;

	return status;
}


/*!	snooze() for internal kernel use only; doesn't interrupt on signals. */
status_t
snooze(bigtime_t timeout)
{
	return snooze_etc(timeout, B_SYSTEM_TIMEBASE, B_RELATIVE_TIMEOUT);
}


/*!
	snooze_until() for internal kernel use only; doesn't interrupt on
	signals.
*/
status_t
snooze_until(bigtime_t timeout, int timebase)
{
	return snooze_etc(timeout, timebase, B_ABSOLUTE_TIMEOUT);
}


status_t
wait_for_thread(thread_id thread, status_t *_returnCode)
{
	return wait_for_thread_etc(thread, 0, 0, _returnCode);
}


status_t
suspend_thread(thread_id id)
{
	if (id <= 0)
		return B_BAD_VALUE;

	return send_signal(id, SIGSTOP);
}


status_t
resume_thread(thread_id id)
{
	if (id <= 0)
		return B_BAD_VALUE;

	return send_signal(id, SIGCONT);
}


thread_id
spawn_kernel_thread(thread_func function, const char *name, int32 priority,
	void *arg)
{
	return create_thread(name, team_get_kernel_team()->id,
		(thread_entry_func)function, arg, NULL, priority, true, -1);
}


/* TODO: split this; have kernel version set kerrno */
int
getrlimit(int resource, struct rlimit * rlp)
{
	if (!rlp)
		return B_BAD_ADDRESS;

	switch (resource) {
		case RLIMIT_NOFILE:
		case RLIMIT_NOVMON:
			return vfs_getrlimit(resource, rlp);

		default:
			return EINVAL;
	}

	return 0;
}


/* TODO: split this; have kernel version set kerrno */
int
setrlimit(int resource, const struct rlimit * rlp)
{
	if (!rlp)
		return B_BAD_ADDRESS;

	switch (resource) {
		case RLIMIT_NOFILE:
		case RLIMIT_NOVMON:
			return vfs_setrlimit(resource, rlp);

		default:
			return EINVAL;
	}

	return 0;
}


//	#pragma mark - syscalls


void
_user_exit_thread(status_t returnValue)
{
	exit_thread(returnValue);
}


status_t
_user_kill_thread(thread_id thread)
{
	return kill_thread(thread);
}


status_t
_user_resume_thread(thread_id thread)
{
	return resume_thread(thread);
}


status_t
_user_suspend_thread(thread_id thread)
{
	return suspend_thread(thread);
}


status_t
_user_rename_thread(thread_id thread, const char *userName)
{
	char name[B_OS_NAME_LENGTH];

	if (!IS_USER_ADDRESS(userName)
		|| userName == NULL
		|| user_strlcpy(name, userName, B_OS_NAME_LENGTH) < B_OK)
		return B_BAD_ADDRESS;

	return rename_thread(thread, name);
}


int32
_user_set_thread_priority(thread_id thread, int32 newPriority)
{
	return set_thread_priority(thread, newPriority);
}


thread_id
_user_spawn_thread(int32 (*entry)(thread_func, void *), const char *userName,
	int32 priority, void *data1, void *data2)
{
	char name[B_OS_NAME_LENGTH];
	thread_id threadID;

	if (!IS_USER_ADDRESS(entry) || entry == NULL
		|| (userName != NULL && (!IS_USER_ADDRESS(userName)
			|| user_strlcpy(name, userName, B_OS_NAME_LENGTH) < B_OK)))
		return B_BAD_ADDRESS;

	threadID = create_thread(userName != NULL ? name : "user thread",
		thread_get_current_thread()->team->id, entry,
		data1, data2, priority, false, -1);

	user_debug_thread_created(threadID);

	return threadID;
}


status_t
_user_snooze_etc(bigtime_t timeout, int timebase, uint32 flags)
{
	return snooze_etc(timeout, timebase, flags | B_CAN_INTERRUPT);
}


void
_user_thread_yield(void)
{
	thread_yield();
}


status_t
_user_get_thread_info(thread_id id, thread_info *userInfo)
{
	thread_info info;
	status_t status;

	if (!IS_USER_ADDRESS(userInfo))
		return B_BAD_ADDRESS;

	status = _get_thread_info(id, &info, sizeof(thread_info));

	if (status >= B_OK
		&& user_memcpy(userInfo, &info, sizeof(thread_info)) < B_OK)
		return B_BAD_ADDRESS;

	return status;
}


status_t
_user_get_next_thread_info(team_id team, int32 *userCookie,
	thread_info *userInfo)
{
	status_t status;
	thread_info info;
	int32 cookie;

	if (!IS_USER_ADDRESS(userCookie) || !IS_USER_ADDRESS(userInfo)
		|| user_memcpy(&cookie, userCookie, sizeof(int32)) < B_OK)
		return B_BAD_ADDRESS;

	status = _get_next_thread_info(team, &cookie, &info, sizeof(thread_info));
	if (status < B_OK)
		return status;

	if (user_memcpy(userCookie, &cookie, sizeof(int32)) < B_OK
		|| user_memcpy(userInfo, &info, sizeof(thread_info)) < B_OK)
		return B_BAD_ADDRESS;

	return status;
}


thread_id
_user_find_thread(const char *userName)
{
	char name[B_OS_NAME_LENGTH];

	if (userName == NULL)
		return find_thread(NULL);

	if (!IS_USER_ADDRESS(userName)
		|| user_strlcpy(name, userName, sizeof(name)) < B_OK)
		return B_BAD_ADDRESS;

	return find_thread(name);
}


status_t
_user_wait_for_thread(thread_id id, status_t *userReturnCode)
{
	status_t returnCode;
	status_t status;

	if (userReturnCode != NULL && !IS_USER_ADDRESS(userReturnCode))
		return B_BAD_ADDRESS;

	status = wait_for_thread_etc(id, B_CAN_INTERRUPT, 0, &returnCode);

	if (status == B_OK && userReturnCode != NULL
		&& user_memcpy(userReturnCode, &returnCode, sizeof(status_t)) < B_OK)
		return B_BAD_ADDRESS;

	return status;
}


bool
_user_has_data(thread_id thread)
{
	return has_data(thread);
}


status_t
_user_send_data(thread_id thread, int32 code, const void *buffer,
	size_t bufferSize)
{
	if (!IS_USER_ADDRESS(buffer))
		return B_BAD_ADDRESS;

	return send_data_etc(thread, code, buffer, bufferSize,
		B_KILL_CAN_INTERRUPT);
		// supports userland buffers
}


status_t
_user_receive_data(thread_id *_userSender, void *buffer, size_t bufferSize)
{
	thread_id sender;
	status_t code;

	if (!IS_USER_ADDRESS(_userSender)
		|| !IS_USER_ADDRESS(buffer))
		return B_BAD_ADDRESS;

	code = receive_data_etc(&sender, buffer, bufferSize, B_KILL_CAN_INTERRUPT);
		// supports userland buffers

	if (user_memcpy(_userSender, &sender, sizeof(thread_id)) < B_OK)
		return B_BAD_ADDRESS;

	return code;
}


// ToDo: the following two functions don't belong here


int
_user_getrlimit(int resource, struct rlimit *urlp)
{
	struct rlimit rl;
	int ret;

	if (urlp == NULL)
		return EINVAL;

	if (!IS_USER_ADDRESS(urlp))
		return B_BAD_ADDRESS;

	ret = getrlimit(resource, &rl);

	if (ret == 0) {
		ret = user_memcpy(urlp, &rl, sizeof(struct rlimit));
		if (ret < 0)
			return ret;

		return 0;
	}

	return ret;
}


int
_user_setrlimit(int resource, const struct rlimit *userResourceLimit)
{
	struct rlimit resourceLimit;

	if (userResourceLimit == NULL)
		return EINVAL;

	if (!IS_USER_ADDRESS(userResourceLimit)
		|| user_memcpy(&resourceLimit, userResourceLimit,
			sizeof(struct rlimit)) < B_OK)
		return B_BAD_ADDRESS;

	return setrlimit(resource, &resourceLimit);
}