freebsd-dev/lib/libc_r/uthread/uthread_create.c

/*
 * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by John Birrell.
 * 4. Neither the name of the author nor the names of any co-contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD$
 */
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <stddef.h>
#include <sys/time.h>
#include <sys/param.h>
#include <sys/mman.h>
#ifdef _THREAD_SAFE
#include <machine/reg.h>
#include <pthread.h>
#include "pthread_private.h"
#include "libc_private.h"

static u_int64_t next_uniqueid = 1;

#define OFF(f)	offsetof(struct pthread, f)
int _thread_next_offset			= OFF(tle.tqe_next);
int _thread_uniqueid_offset		= OFF(uniqueid);
int _thread_state_offset		= OFF(state);
int _thread_name_offset			= OFF(name);
int _thread_ctxtype_offset		= OFF(ctxtype);
int _thread_ctx_offset			= OFF(ctx);
#undef OFF

int _thread_PS_RUNNING_value		= PS_RUNNING;
int _thread_PS_DEAD_value		= PS_DEAD;
int _thread_CTX_JB_NOSIG_value		= CTX_JB_NOSIG;
int _thread_CTX_JB_value		= CTX_JB;
int _thread_CTX_SJB_value		= CTX_SJB;
int _thread_CTX_UC_value		= CTX_UC;

int
pthread_create(pthread_t * thread, const pthread_attr_t * attr,
	       void *(*start_routine) (void *), void *arg)
{
	struct itimerval itimer;
	int		f_gc = 0;
	int             ret = 0;
	pthread_t       gc_thread;
	pthread_t       new_thread;
	pthread_attr_t	pattr;
	void           *stack;

	/*
	 * Locking functions in libc are required when there are
	 * threads other than the initial thread.
	 */
	__isthreaded = 1;

	/* Allocate memory for the thread structure: */
	if ((new_thread = (pthread_t) malloc(sizeof(struct pthread))) == NULL) {
		/* Insufficient memory to create a thread: */
		ret = EAGAIN;
	} else {
		/* Check if default thread attributes are required: */
		if (attr == NULL || *attr == NULL) {
			/* Use the default thread attributes: */
			pattr = &pthread_attr_default;
		} else {
			pattr = *attr;
		}
		/* Check if a stack was specified in the thread attributes: */
		if ((stack = pattr->stackaddr_attr) != NULL) {
		}
		/* Allocate memory for a default-size stack: */
		else if (pattr->stacksize_attr == PTHREAD_STACK_DEFAULT) {
			struct stack	*spare_stack;
			
			/* Allocate or re-use a default-size stack. */
			
			/*
			 * Use the garbage collector mutex for synchronization
			 * of the spare stack list.
			 */
			if (pthread_mutex_lock(&_gc_mutex) != 0)
				PANIC("Cannot lock gc mutex");
			
			if ((spare_stack = SLIST_FIRST(&_stackq)) != NULL) {
				/* Use the spare stack. */
				SLIST_REMOVE_HEAD(&_stackq, qe);
				
				/* Unlock the garbage collector mutex. */
				if (pthread_mutex_unlock(&_gc_mutex) != 0)
					PANIC("Cannot unlock gc mutex");
				
				stack = sizeof(struct stack)
				    + (void *) spare_stack
				    - PTHREAD_STACK_DEFAULT;
			} else {
				/* Allocate a new stack. */
				stack = _next_stack + PTHREAD_STACK_GUARD;

				/*
				 * Even if stack allocation fails, we don't want
				 * to try to use this location again, so
				 * unconditionally decrement _next_stack.  Under
				 * normal operating conditions, the most likely
				 * reason for an mmap() error is a stack
				 * overflow of the adjacent thread stack.
				 */
				_next_stack -= (PTHREAD_STACK_DEFAULT
				    + PTHREAD_STACK_GUARD);

				/* Unlock the garbage collector mutex. */
				if (pthread_mutex_unlock(&_gc_mutex) != 0)
					PANIC("Cannot unlock gc mutex");

				/* Stack: */
				if (mmap(stack, PTHREAD_STACK_DEFAULT,
				    PROT_READ | PROT_WRITE, MAP_STACK,
				    -1, 0) == MAP_FAILED) {
					ret = EAGAIN;
					free(new_thread);
				}
			}
		}
		/*
		 * The user wants a stack of a particular size.  Lets hope they
		 * really know what they want, and simply malloc the stack.
		 */
		else if ((stack = (void *) malloc(pattr->stacksize_attr))
		    == NULL) {
			/* Insufficient memory to create a thread: */
			ret = EAGAIN;
			free(new_thread);
		}

		/* Check for errors: */
		if (ret != 0) {
		} else {
			/* Initialise the thread structure: */
			memset(new_thread, 0, sizeof(struct pthread));
			new_thread->slice_usec = -1;
			new_thread->stack = stack;
			new_thread->start_routine = start_routine;
			new_thread->arg = arg;

			new_thread->cancelflags = PTHREAD_CANCEL_ENABLE |
			    PTHREAD_CANCEL_DEFERRED;

			/*
			 * Write a magic value to the thread structure
			 * to help identify valid ones:
			 */
			new_thread->magic = PTHREAD_MAGIC;

			/* Initialise the thread for signals: */
			new_thread->sigmask = _thread_run->sigmask;
			new_thread->sigmask_seqno = 0;

			/* Initialize the signal frame: */
			new_thread->curframe = NULL;

			/* Initialise the jump buffer: */
			_setjmp(new_thread->ctx.jb);

			/*
			 * Set up new stack frame so that it looks like it
			 * returned from a longjmp() to the beginning of
			 * _thread_start().
			 */
			SET_RETURN_ADDR_JB(new_thread->ctx.jb, _thread_start);

			/* The stack starts high and builds down: */
			SET_STACK_JB(new_thread->ctx.jb,
			    (long)new_thread->stack + pattr->stacksize_attr
			    - sizeof(double));

			/* Initialize the rest of the frame: */
			new_thread->ctxtype = CTX_JB_NOSIG;

			/* Copy the thread attributes: */
			memcpy(&new_thread->attr, pattr, sizeof(struct pthread_attr));

			/*
			 * Check if this thread is to inherit the scheduling
			 * attributes from its parent:
			 */
			if (new_thread->attr.flags & PTHREAD_INHERIT_SCHED) {
				/* Copy the scheduling attributes: */
				new_thread->base_priority =
				    _thread_run->base_priority &
				    ~PTHREAD_SIGNAL_PRIORITY;
				new_thread->attr.prio =
				    _thread_run->base_priority &
				    ~PTHREAD_SIGNAL_PRIORITY;
				new_thread->attr.sched_policy =
				    _thread_run->attr.sched_policy;
			} else {
				/*
				 * Use just the thread priority, leaving the
				 * other scheduling attributes as their
				 * default values:
				 */
				new_thread->base_priority =
				    new_thread->attr.prio;
			}
			new_thread->active_priority = new_thread->base_priority;
			new_thread->inherited_priority = 0;

			/* Initialise the join queue for the new thread: */
			TAILQ_INIT(&(new_thread->join_queue));

			/* Initialize the mutex queue: */
			TAILQ_INIT(&new_thread->mutexq);

			/* Initialise hooks in the thread structure: */
			new_thread->specific_data = NULL;
			new_thread->cleanup = NULL;
			new_thread->flags = 0;
			new_thread->poll_data.nfds = 0;
			new_thread->poll_data.fds = NULL;
			new_thread->continuation = NULL;

			/*
			 * Defer signals to protect the scheduling queues
			 * from access by the signal handler:
			 */
			_thread_kern_sig_defer();

			/*
			 * Initialise the unique id which GDB uses to
			 * track threads.
			 */
			new_thread->uniqueid = next_uniqueid++;

			/*
			 * Check if the garbage collector thread
			 * needs to be started.
			 */
			f_gc = (TAILQ_FIRST(&_thread_list) == _thread_initial);

			/* Add the thread to the linked list of all threads: */
			TAILQ_INSERT_HEAD(&_thread_list, new_thread, tle);

			if (pattr->suspend == PTHREAD_CREATE_SUSPENDED)
				new_thread->state = PS_SUSPENDED;
			else {
				new_thread->state = PS_RUNNING;
				PTHREAD_PRIOQ_INSERT_TAIL(new_thread);
			}

			/*
			 * Undefer and handle pending signals, yielding
			 * if necessary.
			 */
			_thread_kern_sig_undefer();

			/* Return a pointer to the thread structure: */
			(*thread) = new_thread;

			if (f_gc != 0) {
				/* Install the scheduling timer: */
				itimer.it_interval.tv_sec = 0;
				itimer.it_interval.tv_usec = _clock_res_usec;
				itimer.it_value = itimer.it_interval;
				if (setitimer(_ITIMER_SCHED_TIMER, &itimer,
				    NULL) != 0)
					PANIC("Cannot set interval timer");
			}

			/* Schedule the new user thread: */
			_thread_kern_sched(NULL);

			/*
			 * Start a garbage collector thread
			 * if necessary.
			 */
			if (f_gc && pthread_create(&gc_thread,NULL,
				    _thread_gc,NULL) != 0)
				PANIC("Can't create gc thread");

		}
	}

	/* Return the status: */
	return (ret);
}

void
_thread_start(void)
{
	/* We just left the scheduler via longjmp: */
	_thread_kern_in_sched = 0;

	/* Run the current thread's start routine with argument: */
	pthread_exit(_thread_run->start_routine(_thread_run->arg));

	/* This point should never be reached. */
	PANIC("Thread has resumed after exit");
}
#endif