cond.c

#include <sys/types.h>

#include <kernel/mutex.h>
#include <kernel/sched.h>
#include <kernel/thread.h>

#include "linux/list.h"

static LIST_HEAD(cond_head);

static struct thread_info *find_other_thread(pthread_cond_t *cond)
{
    struct thread_info *other;

    list_for_each_entry(other, &cond_head, ti_q)
    {
        if (other->ti_private == cond)
            return other;
    }

    return NULL;
}

int sys_pthread_cond_wait(pthread_cond_t *cond, kernel_mutex_t *mutex)
{
    CURRENT_THREAD_INFO(curr_thread);
    curr_thread->ti_private = cond;
    curr_thread->ti_state = THREAD_STATE_BLOCKED;
    sched_dequeue(curr_thread);
    list_add_tail(&curr_thread->ti_q, &cond_head);
    sys_pthread_mutex_unlock(mutex);

    /* contend for the lock */
    sys_pthread_mutex_lock(mutex);

    return 0;
}

int sys_pthread_cond_signal(pthread_cond_t *cond)
{
    struct thread_info *other;

    other = find_other_thread(cond);
    if (!other)
        return 0;

    list_del(&other->ti_q);
    sched_enqueue(other);
    CURRENT_THREAD_INFO(curr_thread);
    if (other->ti_priority >= curr_thread->ti_priority) {
        sched_enqueue(curr_thread);
        sched_elect(SCHED_OPT_NONE);
    }

    return 0;
}