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eceb656c49
* should not have any effect as long as `unsigned` and `int` are compatible * also fix two cosmetic `unsigned int` -> `unsigned` for consistency
128 lines
3.4 KiB
C
128 lines
3.4 KiB
C
/*
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* Copyright (C) 2013 Freie Universität Berlin
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup core_sync
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* @{
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*
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* @file mutex.c
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* @brief Kernel mutex implementation
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*
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* @author Kaspar Schleiser <kaspar@schleiser.de>
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*
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* @}
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*/
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#include <stdio.h>
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#include <inttypes.h>
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#include "mutex.h"
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#include "tcb.h"
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#include "atomic.h"
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#include "kernel.h"
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#include "sched.h"
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#include "thread.h"
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#include "irq.h"
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#include "thread.h"
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#define ENABLE_DEBUG (0)
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#include "debug.h"
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static void mutex_wait(struct mutex_t *mutex);
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int mutex_trylock(struct mutex_t *mutex)
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{
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DEBUG("%s: trylocking to get mutex. val: %u\n", sched_active_thread->name, mutex->val);
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return (atomic_set_return(&mutex->val, 1) == 0);
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}
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void mutex_lock(struct mutex_t *mutex)
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{
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DEBUG("%s: trying to get mutex. val: %u\n", sched_active_thread->name, mutex->val);
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if (atomic_set_return(&mutex->val, 1) != 0) {
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/* mutex was locked. */
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mutex_wait(mutex);
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}
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}
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static void mutex_wait(struct mutex_t *mutex)
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{
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unsigned irqstate = disableIRQ();
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DEBUG("%s: Mutex in use. %u\n", sched_active_thread->name, mutex->val);
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if (mutex->val == 0) {
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/* somebody released the mutex. return. */
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mutex->val = 1;
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DEBUG("%s: mutex_wait early out. %u\n", sched_active_thread->name, mutex->val);
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restoreIRQ(irqstate);
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return;
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}
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sched_set_status((tcb_t*) sched_active_thread, STATUS_MUTEX_BLOCKED);
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priority_queue_node_t n;
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n.priority = (unsigned int) sched_active_thread->priority;
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n.data = (unsigned int) sched_active_thread;
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n.next = NULL;
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DEBUG("%s: Adding node to mutex queue: prio: %" PRIu32 "\n", sched_active_thread->name, n.priority);
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priority_queue_add(&(mutex->queue), &n);
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restoreIRQ(irqstate);
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thread_yield_higher();
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/* we were woken up by scheduler. waker removed us from queue. we have the mutex now. */
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}
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void mutex_unlock(struct mutex_t *mutex)
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{
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DEBUG("%s: unlocking mutex. val: %u pid: %" PRIkernel_pid "\n", sched_active_thread->name, mutex->val, sched_active_pid);
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unsigned irqstate = disableIRQ();
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if (mutex->val != 0) {
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priority_queue_node_t *next = priority_queue_remove_head(&(mutex->queue));
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if (next) {
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tcb_t *process = (tcb_t *) next->data;
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DEBUG("%s: waking up waiter.\n", process->name);
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sched_set_status(process, STATUS_PENDING);
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sched_switch(process->priority);
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}
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else {
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mutex->val = 0;
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}
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}
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restoreIRQ(irqstate);
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}
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void mutex_unlock_and_sleep(struct mutex_t *mutex)
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{
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DEBUG("%s: unlocking mutex. val: %u pid: %" PRIkernel_pid ", and taking a nap\n", sched_active_thread->name, mutex->val, sched_active_pid);
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unsigned irqstate = disableIRQ();
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if (mutex->val != 0) {
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priority_queue_node_t *next = priority_queue_remove_head(&(mutex->queue));
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if (next) {
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tcb_t *process = (tcb_t *) next->data;
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DEBUG("%s: waking up waiter.\n", process->name);
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sched_set_status(process, STATUS_PENDING);
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}
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else {
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mutex->val = 0;
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}
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}
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DEBUG("%s: going to sleep.\n", sched_active_thread->name);
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sched_set_status((tcb_t*) sched_active_thread, STATUS_SLEEPING);
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restoreIRQ(irqstate);
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thread_yield_higher();
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}
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