source: mainline/generic/src/proc/thread.c@ b4cad8b2

/*
 * Copyright (C) 2001-2004 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <proc/scheduler.h>
#include <proc/thread.h>
#include <proc/task.h>
#include <mm/heap.h>
#include <mm/frame.h>
#include <mm/page.h>
#include <arch/asm.h>
#include <arch.h>
#include <synch/synch.h>
#include <synch/spinlock.h>
#include <synch/waitq.h>
#include <synch/rwlock.h>
#include <cpu.h>
#include <func.h>
#include <context.h>
#include <list.h>
#include <typedefs.h>
#include <time/clock.h>
#include <list.h>
#include <config.h>
#include <arch/interrupt.h>
#include <smp/ipi.h>
#include <arch/faddr.h>
#include <arch/atomic.h>
#include <memstr.h>

char *thread_states[] = {"Invalid", "Running", "Sleeping", "Ready", "Entering", "Exiting"}; /**< Thread states */

SPINLOCK_INITIALIZE(threads_lock);      /**< Lock protecting threads_head list. For locking rules, see declaration thereof. */
LIST_INITIALIZE(threads_head);          /**< List of all threads. */

SPINLOCK_INITIALIZE(tidlock);
__u32 last_tid = 0;


/** Thread wrapper
 *
 * This wrapper is provided to ensure that every thread
 * makes a call to thread_exit() when its implementing
 * function returns.
 *
 * interrupts_disable() is assumed.
 *
 */
static void cushion(void)
{
        void (*f)(void *) = THREAD->thread_code;
        void *arg = THREAD->thread_arg;

        /* this is where each thread wakes up after its creation */
        before_thread_runs();

        spinlock_unlock(&THREAD->lock);
        interrupts_enable();

        f(arg);
        thread_exit();
        /* not reached */
}


/** Initialize threads
 *
 * Initialize kernel threads support.
 *
 */
void thread_init(void)
{
        THREAD = NULL;
        atomic_set(&nrdy,0);
}


/** Make thread ready
 *
 * Switch thread t to the ready state.
 *
 * @param t Thread to make ready.
 *
 */
void thread_ready(thread_t *t)
{
        cpu_t *cpu;
        runq_t *r;
        ipl_t ipl;
        int i, avg;

        ipl = interrupts_disable();

        spinlock_lock(&t->lock);

        i = (t->priority < RQ_COUNT -1) ? ++t->priority : t->priority;
        
        cpu = CPU;
        if (t->flags & X_WIRED) {
                cpu = t->cpu;
        }
        spinlock_unlock(&t->lock);
        
        /*
         * Append t to respective ready queue on respective processor.
         */
        r = &cpu->rq[i];
        spinlock_lock(&r->lock);
        list_append(&t->rq_link, &r->rq_head);
        r->n++;
        spinlock_unlock(&r->lock);

        atomic_inc(&nrdy);
        avg = atomic_get(&nrdy) / config.cpu_active;

        spinlock_lock(&cpu->lock);
        if ((++cpu->nrdy) > avg) {
                /*
                 * If there are idle halted CPU's, this will wake them up.
                 */
                ipi_broadcast(VECTOR_WAKEUP_IPI);
        }       
        spinlock_unlock(&cpu->lock);

        interrupts_restore(ipl);
}


/** Create new thread
 *
 * Create a new thread.
 *
 * @param func  Thread's implementing function.
 * @param arg   Thread's implementing function argument.
 * @param task  Task to which the thread belongs.
 * @param flags Thread flags.
 *
 * @return New thread's structure on success, NULL on failure.
 *
 */
thread_t *thread_create(void (* func)(void *), void *arg, task_t *task, int flags)
{
        thread_t *t;
        __address frame_ks, frame_us = NULL;

        t = (thread_t *) malloc(sizeof(thread_t));
        if (t) {
                ipl_t ipl;
        
                spinlock_initialize(&t->lock, "thread_t_lock");
        
                frame_ks = frame_alloc(FRAME_KA, ONE_FRAME);
                if (THREAD_USER_STACK & flags) {
                        frame_us = frame_alloc(FRAME_KA, ONE_FRAME);
                }

                ipl = interrupts_disable();
                spinlock_lock(&tidlock);
                t->tid = ++last_tid;
                spinlock_unlock(&tidlock);
                interrupts_restore(ipl);
                
                memsetb(frame_ks, THREAD_STACK_SIZE, 0);
                link_initialize(&t->rq_link);
                link_initialize(&t->wq_link);
                link_initialize(&t->th_link);
                link_initialize(&t->threads_link);
                t->kstack = (__u8 *) frame_ks;
                t->ustack = (__u8 *) frame_us;
                
                context_save(&t->saved_context);
                context_set(&t->saved_context, FADDR(cushion), (__address) t->kstack, THREAD_STACK_SIZE);
                
                the_initialize((the_t *) t->kstack);

                ipl = interrupts_disable();
                t->saved_context.ipl = interrupts_read();
                interrupts_restore(ipl);
                
                t->thread_code = func;
                t->thread_arg = arg;
                t->ticks = -1;
                t->priority = -1;               /* start in rq[0] */
                t->cpu = NULL;
                t->flags = 0;
                t->state = Entering;
                t->call_me = NULL;
                t->call_me_with = NULL;
                
                timeout_initialize(&t->sleep_timeout);
                t->sleep_queue = NULL;
                t->timeout_pending = 0;
                
                t->rwlock_holder_type = RWLOCK_NONE;
                
                t->task = task;
                
                t->fpu_context_exists=0;
                t->fpu_context_engaged=0;
                
                /*
                 * Register this thread in the system-wide list.
                 */
                ipl = interrupts_disable();             
                spinlock_lock(&threads_lock);
                list_append(&t->threads_link, &threads_head);
                spinlock_unlock(&threads_lock);

                /*
                 * Attach to the containing task.
                 */
                spinlock_lock(&task->lock);
                list_append(&t->th_link, &task->th_head);
                spinlock_unlock(&task->lock);

                interrupts_restore(ipl);
        }

        return t;
}


/** Make thread exiting
 *
 * End current thread execution and switch it to the exiting
 * state. All pending timeouts are executed.
 *
 */
void thread_exit(void)
{
        ipl_t ipl;

restart:
        ipl = interrupts_disable();
        spinlock_lock(&THREAD->lock);
        if (THREAD->timeout_pending) { /* busy waiting for timeouts in progress */
                spinlock_unlock(&THREAD->lock);
                interrupts_restore(ipl);
                goto restart;
        }
        THREAD->state = Exiting;
        spinlock_unlock(&THREAD->lock);
        scheduler();
}


/** Thread sleep
 *
 * Suspend execution of the current thread.
 *
 * @param sec Number of seconds to sleep.
 *
 */
void thread_sleep(__u32 sec)
{
        thread_usleep(sec*1000000);
}


/** Thread usleep
 *
 * Suspend execution of the current thread.
 *
 * @param usec Number of microseconds to sleep.
 *
 */     
void thread_usleep(__u32 usec)
{
        waitq_t wq;
                                  
        waitq_initialize(&wq);

        (void) waitq_sleep_timeout(&wq, usec, SYNCH_NON_BLOCKING);
}


/** Register thread out-of-context invocation
 *
 * Register a function and its argument to be executed
 * on next context switch to the current thread.
 *
 * @param call_me      Out-of-context function.
 * @param call_me_with Out-of-context function argument.
 *
 */
void thread_register_call_me(void (* call_me)(void *), void *call_me_with)
{
        ipl_t ipl;
        
        ipl = interrupts_disable();
        spinlock_lock(&THREAD->lock);
        THREAD->call_me = call_me;
        THREAD->call_me_with = call_me_with;
        spinlock_unlock(&THREAD->lock);
        interrupts_restore(ipl);
}