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/*

 * 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;

    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, send_ipi = 0;

    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 = 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);

}