76092ddf33
This can be turned back on when the library is compiled with -DMTHREAD_STRICT (which enables more sanity checks). However, always performing this check shows up in system profiling results.
282 lines
7.4 KiB
C
282 lines
7.4 KiB
C
#include <minix/mthread.h>
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#include "global.h"
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#include "proto.h"
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#ifdef MTHREAD_STRICT
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static struct __mthread_mutex *vm_front, *vm_rear;
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static void mthread_mutex_add(mthread_mutex_t *m);
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static void mthread_mutex_remove(mthread_mutex_t *m);
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#else
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# define mthread_mutex_add(m) ((*m)->mm_magic = MTHREAD_INIT_MAGIC)
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# define mthread_mutex_remove(m) ((*m)->mm_magic = MTHREAD_NOT_INUSE)
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#endif
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/*===========================================================================*
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* mthread_init_valid_mutexes *
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*===========================================================================*/
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void mthread_init_valid_mutexes(void)
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{
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#ifdef MTHREAD_STRICT
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/* Initialize list of valid mutexes */
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vm_front = vm_rear = NULL;
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#endif
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}
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/*===========================================================================*
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* mthread_mutex_add *
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*===========================================================================*/
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#ifdef MTHREAD_STRICT
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static void mthread_mutex_add(m)
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mthread_mutex_t *m;
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{
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/* Add mutex to list of valid, initialized mutexes */
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if (vm_front == NULL) { /* Empty list */
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vm_front = *m;
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(*m)->mm_prev = NULL;
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} else {
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vm_rear->mm_next = *m;
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(*m)->mm_prev = vm_rear;
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}
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(*m)->mm_next = NULL;
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vm_rear = *m;
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}
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#endif
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/*===========================================================================*
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* mthread_mutex_destroy *
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*===========================================================================*/
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int mthread_mutex_destroy(mutex)
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mthread_mutex_t *mutex;
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{
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/* Invalidate mutex and deallocate resources. */
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mthread_thread_t t;
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mthread_tcb_t *tcb;
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MTHREAD_CHECK_INIT(); /* Make sure mthreads is initialized */
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if (mutex == NULL)
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return(EINVAL);
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if (!mthread_mutex_valid(mutex))
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return(EINVAL);
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else if ((*mutex)->mm_owner != NO_THREAD)
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return(EBUSY);
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/* Check if this mutex is not associated with a condition */
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for (t = (mthread_thread_t) 0; t < no_threads; t++) {
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tcb = mthread_find_tcb(t);
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if (tcb->m_state == MS_CONDITION) {
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if (tcb->m_cond != NULL && tcb->m_cond->mc_mutex == *mutex)
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return(EBUSY);
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}
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}
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/* Not in use; invalidate it */
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mthread_mutex_remove(mutex);
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free(*mutex);
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*mutex = NULL;
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return(0);
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}
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/*===========================================================================*
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* mthread_mutex_init *
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*===========================================================================*/
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int mthread_mutex_init(mutex, mattr)
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mthread_mutex_t *mutex; /* Mutex that is to be initialized */
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mthread_mutexattr_t *mattr; /* Mutex attribute */
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{
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/* Initialize the mutex to a known state. Attributes are not supported */
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struct __mthread_mutex *m;
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MTHREAD_CHECK_INIT(); /* Make sure mthreads is initialized */
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if (mutex == NULL)
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return(EAGAIN);
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else if (mattr != NULL)
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return(ENOSYS);
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#ifdef MTHREAD_STRICT
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else if (mthread_mutex_valid(mutex))
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return(EBUSY);
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#endif
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else if ((m = malloc(sizeof(struct __mthread_mutex))) == NULL)
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return(ENOMEM);
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mthread_queue_init(&m->mm_queue);
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m->mm_owner = NO_THREAD;
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*mutex = (mthread_mutex_t) m;
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mthread_mutex_add(mutex); /* Validate mutex; mutex now in use */
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return(0);
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}
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/*===========================================================================*
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* mthread_mutex_lock *
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*===========================================================================*/
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int mthread_mutex_lock(mutex)
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mthread_mutex_t *mutex; /* Mutex that is to be locked */
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{
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/* Try to lock this mutex. If already locked, append the current thread to
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* FIFO queue associated with this mutex and suspend the thread. */
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struct __mthread_mutex *m;
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MTHREAD_CHECK_INIT(); /* Make sure mthreads is initialized */
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if (mutex == NULL)
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return(EINVAL);
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m = (struct __mthread_mutex *) *mutex;
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if (!mthread_mutex_valid(&m))
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return(EINVAL);
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else if (m->mm_owner == NO_THREAD) { /* Not locked */
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m->mm_owner = current_thread;
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} else if (m->mm_owner == current_thread) {
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return(EDEADLK);
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} else {
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mthread_queue_add(&m->mm_queue, current_thread);
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mthread_suspend(MS_MUTEX);
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}
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/* When we get here we acquired the lock. */
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return(0);
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}
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/*===========================================================================*
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* mthread_mutex_remove *
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*===========================================================================*/
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#ifdef MTHREAD_STRICT
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static void mthread_mutex_remove(m)
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mthread_mutex_t *m;
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{
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/* Remove mutex from list of valid, initialized mutexes */
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if ((*m)->mm_prev == NULL)
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vm_front = (*m)->mm_next;
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else
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(*m)->mm_prev->mm_next = (*m)->mm_next;
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if ((*m)->mm_next == NULL)
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vm_rear = (*m)->mm_prev;
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else
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(*m)->mm_next->mm_prev = (*m)->mm_prev;
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}
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#endif
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/*===========================================================================*
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* mthread_mutex_trylock *
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*===========================================================================*/
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int mthread_mutex_trylock(mutex)
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mthread_mutex_t *mutex; /* Mutex that is to be locked */
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{
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/* Try to lock this mutex and return OK. If already locked, return error. */
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struct __mthread_mutex *m;
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MTHREAD_CHECK_INIT(); /* Make sure mthreads is initialized */
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if (mutex == NULL)
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return(EINVAL);
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m = (struct __mthread_mutex *) *mutex;
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if (!mthread_mutex_valid(&m))
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return(EINVAL);
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else if (m->mm_owner == current_thread)
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return(EDEADLK);
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else if (m->mm_owner == NO_THREAD) {
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m->mm_owner = current_thread;
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return(0);
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}
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return(EBUSY);
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}
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/*===========================================================================*
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* mthread_mutex_unlock *
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*===========================================================================*/
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int mthread_mutex_unlock(mutex)
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mthread_mutex_t *mutex; /* Mutex that is to be unlocked */
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{
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/* Unlock a previously locked mutex. If there is a pending lock for this mutex
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* by another thread, mark that thread runnable. */
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struct __mthread_mutex *m;
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MTHREAD_CHECK_INIT(); /* Make sure mthreads is initialized */
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if (mutex == NULL)
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return(EINVAL);
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m = (struct __mthread_mutex *) *mutex;
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if (!mthread_mutex_valid(&m))
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return(EINVAL);
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else if (m->mm_owner != current_thread)
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return(EPERM); /* Can't unlock a mutex locked by another thread. */
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m->mm_owner = mthread_queue_remove(&m->mm_queue);
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if (m->mm_owner != NO_THREAD) mthread_unsuspend(m->mm_owner);
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return(0);
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}
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/*===========================================================================*
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* mthread_mutex_valid *
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*===========================================================================*/
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#ifdef MTHREAD_STRICT
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int mthread_mutex_valid(m)
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mthread_mutex_t *m;
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{
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/* Check to see if mutex is on the list of valid mutexes */
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struct __mthread_mutex *loopitem;
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MTHREAD_CHECK_INIT(); /* Make sure mthreads is initialized */
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loopitem = vm_front;
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while (loopitem != NULL) {
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if (loopitem == *m)
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return(1);
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loopitem = loopitem->mm_next;
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}
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return(0);
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}
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#endif
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/*===========================================================================*
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* mthread_mutex_verify *
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*===========================================================================*/
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#ifdef MDEBUG
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int mthread_mutex_verify(void)
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{
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/* Return true when no mutexes are in use */
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int r = 1;
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struct __mthread_mutex *loopitem;
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MTHREAD_CHECK_INIT(); /* Make sure mthreads is initialized */
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#ifdef MTHREAD_STRICT
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loopitem = vm_front;
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while (loopitem != NULL) {
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printf("mutex corruption: owner: %d\n", loopitem->mm_owner);
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loopitem = loopitem->mm_next;
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r = 0;
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}
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#endif
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return(r);
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}
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#endif
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