minix/lib/libmthread/allocate.c

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#define ALLOCATE
#include <errno.h>
#include <minix/mthread.h>
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#include <string.h>
#include <machine/param.h>
#include <sys/mman.h>
#include "global.h"
#include "proto.h"
FORWARD _PROTOTYPE( int mthread_increase_thread_pool, (void) );
FORWARD _PROTOTYPE( void mthread_thread_init, (mthread_thread_t thread,
mthread_attr_t *tattr,
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void *(*proc)(void *),
void *arg) );
FORWARD _PROTOTYPE( void mthread_thread_stop, (mthread_thread_t thread));
FORWARD _PROTOTYPE( void mthread_trampoline, (void) );
PRIVATE int initialized = 0;
#ifndef PGSHIFT
# define PGSHIFT 12 /* XXX: temporarily for ACK */
#endif
#define MTHREAD_GUARDSIZE (1 << PGSHIFT) /* 1 page */
PRIVATE struct __mthread_attr default_attr = { MTHREAD_STACK_MIN,
NULL,
MTHREAD_CREATE_JOINABLE,
NULL, NULL };
/*===========================================================================*
* mthread_equal *
*===========================================================================*/
PUBLIC int mthread_equal(l, r)
mthread_thread_t l;
mthread_thread_t r;
{
/* Compare two thread ids */
mthread_init(); /* Make sure mthreads is initialized */
return(l == r);
}
/*===========================================================================*
* mthread_create *
*===========================================================================*/
PUBLIC int mthread_create(threadid, tattr, proc, arg)
mthread_thread_t *threadid;
mthread_attr_t *tattr;
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void *(*proc)(void *);
void *arg;
{
/* Register procedure proc for execution in a thread. */
mthread_thread_t thread;
mthread_init(); /* Make sure mthreads is initialized */
if (proc == NULL)
return(EINVAL);
if (!mthread_queue_isempty(&free_threads)) {
thread = mthread_queue_remove(&free_threads);
mthread_thread_init(thread, tattr, proc, arg);
used_threads++;
if(threadid != NULL)
*threadid = (mthread_thread_t) thread;
#ifdef MDEBUG
printf("Inited thread %d\n", thread);
#endif
return(0);
} else {
if (mthread_increase_thread_pool() == -1)
return(EAGAIN);
return mthread_create(threadid, tattr, proc, arg);
}
}
/*===========================================================================*
* mthread_detach *
*===========================================================================*/
PUBLIC int mthread_detach(detach)
mthread_thread_t detach;
{
/* Mark a thread as detached. Consequently, upon exit, resources allocated for
* this thread are automatically freed.
*/
mthread_tcb_t *tcb;
mthread_init(); /* Make sure libmthread is initialized */
if (!isokthreadid(detach))
return(ESRCH);
tcb = mthread_find_tcb(detach);
if (tcb->m_state == MS_DEAD) {
return(ESRCH);
} else if (tcb->m_attr.ma_detachstate != MTHREAD_CREATE_DETACHED) {
if (tcb->m_state == MS_EXITING)
mthread_thread_stop(detach);
else
tcb->m_attr.ma_detachstate = MTHREAD_CREATE_DETACHED;
}
return(0);
}
/*===========================================================================*
* mthread_exit *
*===========================================================================*/
PUBLIC void mthread_exit(value)
void *value;
{
/* Make a thread stop running and store the result value. */
mthread_tcb_t *tcb;
mthread_init(); /* Make sure libmthread is initialized */
tcb = mthread_find_tcb(current_thread);
if (tcb->m_state == MS_EXITING) /* Already stopping, nothing to do. */
return;
mthread_cleanup_values();
tcb->m_result = value;
tcb->m_state = MS_EXITING;
if (tcb->m_attr.ma_detachstate == MTHREAD_CREATE_DETACHED) {
mthread_thread_stop(current_thread);
} else {
/* Joinable thread; notify possibly waiting thread */
if (mthread_cond_signal(&(tcb->m_exited)) != 0)
mthread_panic("Couldn't signal exit");
/* The thread that's actually doing the join will eventually clean
* up this thread (i.e., call mthread_thread_stop).
*/
}
mthread_schedule();
}
/*===========================================================================*
* mthread_find_tcb *
*===========================================================================*/
PUBLIC mthread_tcb_t * mthread_find_tcb(thread)
mthread_thread_t thread;
{
mthread_tcb_t *rt = NULL;
if (!isokthreadid(thread)) mthread_panic("Invalid thread id");
if (thread == MAIN_THREAD)
rt = &mainthread;
else
rt = threads[thread];
return(rt);
}
/*===========================================================================*
* mthread_increase_thread_pool *
*===========================================================================*/
PRIVATE int mthread_increase_thread_pool(void)
{
/* Increase thread pool. No fancy algorithms, just double the size. */
mthread_tcb_t **new_tcb;
int new_no_threads, old_no_threads, i;
old_no_threads = no_threads;
if (old_no_threads == 0)
new_no_threads = NO_THREADS;
else
new_no_threads = 2 * old_no_threads;
if (new_no_threads >= MAX_THREAD_POOL) {
mthread_debug("Reached max number of threads");
return(-1);
}
/* Allocate space to store pointers to thread control blocks */
if (old_no_threads == 0) /* No data yet: allocate space */
new_tcb = calloc(new_no_threads, sizeof(mthread_tcb_t *));
else /* Preserve existing data: reallocate space */
new_tcb = realloc(threads, new_no_threads * sizeof(mthread_tcb_t *));
if (new_tcb == NULL) {
mthread_debug("Can't increase thread pool");
return(-1);
}
/* Allocate space for thread control blocks itself */
for (i = old_no_threads; i < new_no_threads; i++) {
new_tcb[i] = malloc(sizeof(mthread_tcb_t));
if (new_tcb[i] == NULL) {
mthread_debug("Can't allocate space for tcb");
return(-1);
}
memset(new_tcb[i], '\0', sizeof(mthread_tcb_t)); /* Clear entry */
}
/* We can breath again, let's tell the others about the good news */
threads = new_tcb;
no_threads = new_no_threads;
/* Add newly available threads to free_threads */
for (i = old_no_threads; i < new_no_threads; i++) {
mthread_queue_add(&free_threads, i);
mthread_thread_reset(i);
}
#ifdef MDEBUG
printf("Increased thread pool from %d to %d threads\n", old_no_threads,
new_no_threads);
#endif
return(0);
}
/*===========================================================================*
* mthread_init *
*===========================================================================*/
PUBLIC void mthread_init(void)
{
/* Initialize thread system; allocate thread structures and start creating
* threads.
*/
if (!initialized) {
no_threads = 0;
used_threads = 0;
need_reset = 0;
running_main_thread = 1;/* mthread_init can only be called from the
* main thread. Calling it from a thread will
* not enter this clause.
*/
if (mthread_getcontext(&(mainthread.m_context)) == -1)
mthread_panic("Couldn't save state for main thread");
current_thread = MAIN_THREAD;
mthread_init_valid_mutexes();
mthread_init_valid_conditions();
mthread_init_valid_attributes();
mthread_init_keys();
mthread_init_scheduler();
initialized = 1;
}
}
/*===========================================================================*
* mthread_join *
*===========================================================================*/
PUBLIC int mthread_join(join, value)
mthread_thread_t join;
void **value;
{
/* Wait for a thread to stop running and copy the result. */
mthread_tcb_t *tcb;
mthread_init(); /* Make sure libmthread is initialized */
if (!isokthreadid(join))
return(ESRCH);
else if (join == current_thread)
return(EDEADLK);
tcb = mthread_find_tcb(join);
if (tcb->m_state == MS_DEAD)
return(ESRCH);
else if (tcb->m_attr.ma_detachstate == MTHREAD_CREATE_DETACHED)
return(EINVAL);
/* When the thread hasn't exited yet, we have to wait for that to happen */
if (tcb->m_state != MS_EXITING) {
mthread_cond_t *c;
mthread_mutex_t *m;
c = &(tcb->m_exited);
m = &(tcb->m_exitm);
if (mthread_mutex_init(m, NULL) != 0)
mthread_panic("Couldn't initialize mutex to join\n");
if (mthread_mutex_lock(m) != 0)
mthread_panic("Couldn't lock mutex to join\n");
if (mthread_cond_wait(c, m) != 0)
mthread_panic("Couldn't wait for join condition\n");
if (mthread_mutex_unlock(m) != 0)
mthread_panic("Couldn't unlock mutex to join\n");
if (mthread_mutex_destroy(m) != 0)
mthread_panic("Couldn't destroy mutex to join\n");
}
/* Thread has exited; copy results */
if(value != NULL)
*value = tcb->m_result;
/* Deallocate resources */
mthread_thread_stop(join);
return(0);
}
/*===========================================================================*
* mthread_once *
*===========================================================================*/
PUBLIC int mthread_once(once, proc)
mthread_once_t *once;
void (*proc)(void);
{
/* Run procedure proc just once */
mthread_init(); /* Make sure libmthread is initialized */
if (once == NULL || proc == NULL)
return(EINVAL);
if (*once != 1) proc();
*once = 1;
return(0);
}
/*===========================================================================*
* mthread_self *
*===========================================================================*/
PUBLIC mthread_thread_t mthread_self(void)
{
/* Return the thread id of the thread calling this function. */
mthread_init(); /* Make sure libmthread is initialized */
return(current_thread);
}
/*===========================================================================*
* mthread_thread_init *
*===========================================================================*/
PRIVATE void mthread_thread_init(thread, tattr, proc, arg)
mthread_thread_t thread;
mthread_attr_t *tattr;
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void *(*proc)(void *);
void *arg;
{
/* Initialize a thread so that it, when unsuspended, will run the given
* procedure with the given parameter. The thread is marked as runnable.
*/
#define THIS_CTX (&(threads[thread]->m_context))
mthread_tcb_t *tcb;
size_t stacksize;
char *stackaddr;
tcb = mthread_find_tcb(thread);
tcb->m_next = NULL;
tcb->m_state = MS_DEAD;
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tcb->m_proc = proc;
tcb->m_arg = arg;
/* Threads use a copy of the provided attributes. This way, if another
* thread modifies the attributes (such as detach state), already running
* threads are not affected.
*/
if (tattr != NULL)
tcb->m_attr = *((struct __mthread_attr *) *tattr);
else {
tcb->m_attr = default_attr;
}
if (mthread_cond_init(&(tcb->m_exited), NULL) != 0)
mthread_panic("Could not initialize thread");
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tcb->m_context.uc_link = NULL;
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/* Construct this thread's context to run procedure proc. */
if (mthread_getcontext(&(tcb->m_context)) == -1)
mthread_panic("Failed to initialize context state");
stacksize = tcb->m_attr.ma_stacksize;
stackaddr = tcb->m_attr.ma_stackaddr;
if (stacksize == (size_t) 0) {
/* User provided too small a stack size. Forget about that stack and
* allocate a new one ourselves.
*/
stacksize = (size_t) MTHREAD_STACK_MIN;
tcb->m_attr.ma_stackaddr = stackaddr = NULL;
}
if (stackaddr == NULL) {
/* Allocate stack space */
size_t guarded_stacksize;
char *guard_start, *guard_end;
stacksize = round_page(stacksize + MTHREAD_GUARDSIZE);
stackaddr = minix_mmap(NULL, stacksize,
PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE,
-1, 0);
if (stackaddr == NULL)
mthread_panic("Failed to allocate stack to thread");
#if (_MINIX_CHIP == _CHIP_INTEL)
guard_start = stackaddr;
guard_end = stackaddr + MTHREAD_GUARDSIZE;
guarded_stacksize = stackaddr + stacksize - guard_end;
/* The stack will be used from (stackaddr+stacksize) to stackaddr. That
* is, growing downwards. So the "top" of the stack may not grow into
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* stackaddr+MTHREAD_GUARDSIZE.
*
* +-------+ stackaddr + stacksize
* | |
* | | |
* | \|/ |
* | |
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* +-------+ stackaddr + MTHREAD_GUARDSIZE
* | GUARD |
* +-------+ stackaddr
*/
#else
# error "Unsupported platform"
#endif
stacksize = guarded_stacksize;
if (minix_munmap(guard_start, MTHREAD_GUARDSIZE) != 0)
mthread_panic("unable to unmap stack space for guard");
tcb->m_context.uc_stack.ss_sp = guard_end;
} else
tcb->m_context.uc_stack.ss_sp = stackaddr;
tcb->m_context.uc_stack.ss_size = stacksize;
makecontext(&(tcb->m_context), mthread_trampoline, 0);
mthread_unsuspend(thread); /* Make thread runnable */
}
/*===========================================================================*
* mthread_thread_reset *
*===========================================================================*/
PUBLIC void mthread_thread_reset(thread)
mthread_thread_t thread;
{
/* Reset the thread to its default values. Free the allocated stack space. */
mthread_tcb_t *rt;
if (!isokthreadid(thread)) mthread_panic("Invalid thread id");
rt = mthread_find_tcb(thread);
rt->m_tid = thread;
rt->m_next = NULL;
rt->m_state = MS_DEAD;
rt->m_proc = NULL;
rt->m_arg = NULL;
rt->m_result = NULL;
rt->m_cond = NULL;
if (rt->m_attr.ma_stackaddr == NULL) { /* We allocated stack space */
if (rt->m_context.uc_stack.ss_sp) {
if (minix_munmap(rt->m_context.uc_stack.ss_sp,
rt->m_context.uc_stack.ss_size) != 0) {
mthread_panic("unable to unmap memory");
}
}
rt->m_context.uc_stack.ss_sp = NULL;
}
rt->m_context.uc_stack.ss_size = 0;
rt->m_context.uc_link = NULL;
}
/*===========================================================================*
* mthread_thread_stop *
*===========================================================================*/
PRIVATE void mthread_thread_stop(thread)
mthread_thread_t thread;
{
/* Stop thread from running. Deallocate resources. */
mthread_tcb_t *stop_thread;
if (!isokthreadid(thread)) mthread_panic("Invalid thread id");
stop_thread = mthread_find_tcb(thread);
if (stop_thread->m_state == MS_DEAD) {
/* Already dead, nothing to do */
return;
}
if (mthread_cond_destroy(&(stop_thread->m_exited)) != 0)
mthread_panic("Could not destroy condition at thread deallocation\n");
/* Can't deallocate ourselves (i.e., we're a detached thread) */
if (thread == current_thread) {
stop_thread->m_state = MS_NEEDRESET;
need_reset++;
} else {
mthread_thread_reset(thread);
used_threads--;
mthread_queue_add(&free_threads, thread);
}
}
/*===========================================================================*
* mthread_trampoline *
*===========================================================================*/
PRIVATE void mthread_trampoline(void)
{
/* Execute the /current_thread's/ procedure. Store its result. */
mthread_tcb_t *tcb;
void *r;
tcb = mthread_find_tcb(current_thread);
r = (tcb->m_proc)(tcb->m_arg);
mthread_exit(r);
}