141 lines
3.0 KiB
C
141 lines
3.0 KiB
C
/*
|
|
* Copyright (c) 2017 Intel Corporation
|
|
*
|
|
* SPDX-License-Identifier: Apache-2.0
|
|
*/
|
|
|
|
#include <kernel.h>
|
|
#include <pthread.h>
|
|
#include "include/ksched.h"
|
|
#include "include/wait_q.h"
|
|
|
|
static void ready_one_thread(_wait_q_t *wq)
|
|
{
|
|
struct k_thread *th = _unpend_first_thread(wq);
|
|
|
|
if (th) {
|
|
_abort_thread_timeout(th);
|
|
_ready_thread(th);
|
|
}
|
|
}
|
|
|
|
static int cond_wait(pthread_cond_t *cv, pthread_mutex_t *mut, int timeout)
|
|
{
|
|
__ASSERT(mut->sem->count == 0, "");
|
|
|
|
int ret, key = irq_lock();
|
|
|
|
mut->sem->count = 1;
|
|
ready_one_thread(&mut->sem->wait_q);
|
|
_pend_current_thread(&cv->wait_q, timeout);
|
|
|
|
ret = _Swap(key);
|
|
|
|
/* FIXME: this extra lock (and the potential context switch it
|
|
* can cause) could be optimized out. At the point of the
|
|
* signal/broadcast, it's possible to detect whether or not we
|
|
* will be swapping back to this particular thread and lock it
|
|
* (i.e. leave the lock variable unchanged) on our behalf.
|
|
* But that requires putting scheduler intelligence into this
|
|
* higher level abstraction and is probably not worth it.
|
|
*/
|
|
pthread_mutex_lock(mut);
|
|
|
|
return ret == -EAGAIN ? -ETIMEDOUT : ret;
|
|
}
|
|
|
|
/* This implements a "fair" scheduling policy: at the end of a POSIX
|
|
* thread call that might result in a change of the current maximum
|
|
* priority thread, we always check and context switch if needed.
|
|
* Note that there is significant dispute in the community over the
|
|
* "right" way to do this and different systems do it differently by
|
|
* default. Zephyr is an RTOS, so we choose latency over
|
|
* throughput. See here for a good discussion of the broad issue:
|
|
*
|
|
* https://blog.mozilla.org/nfroyd/2017/03/29/on-mutex-performance-part-1/
|
|
*/
|
|
static void swap_or_unlock(int key)
|
|
{
|
|
/* API madness: use __ not _ here. The latter checks for our
|
|
* preemption state, but we want to do a switch here even if
|
|
* we can be preempted.
|
|
*/
|
|
if (!_is_in_isr() && __must_switch_threads()) {
|
|
_Swap(key);
|
|
} else {
|
|
irq_unlock(key);
|
|
}
|
|
}
|
|
|
|
int pthread_cond_signal(pthread_cond_t *cv)
|
|
{
|
|
int key = irq_lock();
|
|
|
|
ready_one_thread(&cv->wait_q);
|
|
swap_or_unlock(key);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int pthread_cond_broadcast(pthread_cond_t *cv)
|
|
{
|
|
int key = irq_lock();
|
|
|
|
while (!sys_dlist_is_empty(&cv->wait_q)) {
|
|
ready_one_thread(&cv->wait_q);
|
|
}
|
|
|
|
swap_or_unlock(key);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int pthread_cond_wait(pthread_cond_t *cv, pthread_mutex_t *mut)
|
|
{
|
|
return cond_wait(cv, mut, K_FOREVER);
|
|
}
|
|
|
|
int pthread_cond_timedwait(pthread_cond_t *cv, pthread_mutex_t *mut,
|
|
const struct timespec *to)
|
|
{
|
|
return cond_wait(cv, mut, _ts_to_ms(to));
|
|
}
|
|
|
|
int pthread_mutex_trylock(pthread_mutex_t *m)
|
|
{
|
|
int key = irq_lock(), ret = -EBUSY;
|
|
|
|
if (m->sem->count) {
|
|
m->sem->count = 0;
|
|
ret = 0;
|
|
}
|
|
|
|
irq_unlock(key);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int pthread_barrier_wait(pthread_barrier_t *b)
|
|
{
|
|
int key = irq_lock();
|
|
|
|
b->count++;
|
|
|
|
if (b->count >= b->max) {
|
|
b->count = 0;
|
|
|
|
while (!sys_dlist_is_empty(&b->wait_q)) {
|
|
ready_one_thread(&b->wait_q);
|
|
}
|
|
|
|
if (!__must_switch_threads()) {
|
|
irq_unlock(key);
|
|
return 0;
|
|
}
|
|
} else {
|
|
_pend_current_thread(&b->wait_q, K_FOREVER);
|
|
}
|
|
|
|
return _Swap(key);
|
|
}
|