source: mainline/kernel/generic/src/proc/task.c@ e701eb1

/*
 * 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.
 */

/** @addtogroup genericproc
 * @{
 */

/**
 * @file
 * @brief       Task management.
 */

#include <proc/thread.h>
#include <proc/task.h>
#include <mm/as.h>
#include <mm/slab.h>
#include <atomic.h>
#include <synch/spinlock.h>
#include <synch/waitq.h>
#include <arch.h>
#include <arch/barrier.h>
#include <adt/avl.h>
#include <adt/btree.h>
#include <adt/list.h>
#include <ipc/ipc.h>
#include <ipc/ipcrsc.h>
#include <print.h>
#include <errno.h>
#include <func.h>
#include <string.h>
#include <syscall/copy.h>
#include <macros.h>
#include <ipc/event.h>

/** Spinlock protecting the tasks_tree AVL tree. */
SPINLOCK_INITIALIZE(tasks_lock);

/** AVL tree of active tasks.
 *
 * The task is guaranteed to exist after it was found in the tasks_tree as
 * long as:
 * @li the tasks_lock is held,
 * @li the task's lock is held when task's lock is acquired before releasing
 *     tasks_lock or
 * @li the task's refcount is greater than 0
 *
 */
avltree_t tasks_tree;

static task_id_t task_counter = 0;

static slab_cache_t *task_slab;

/* Forward declarations. */
static void task_kill_internal(task_t *);

/** Initialize kernel tasks support. */
void task_init(void)
{
        TASK = NULL;
        avltree_create(&tasks_tree);
        task_slab = slab_cache_create("task_slab", sizeof(task_t), 0, NULL,
            NULL, 0);
}

/*
 * The idea behind this walker is to kill and count all tasks different from
 * TASK.
 */
static bool task_done_walker(avltree_node_t *node, void *arg)
{
        task_t *t = avltree_get_instance(node, task_t, tasks_tree_node);
        unsigned *cnt = (unsigned *) arg;

        if (t != TASK) {
                (*cnt)++;
#ifdef CONFIG_DEBUG
                printf("[%"PRIu64"] ", t->taskid);
#endif
                task_kill_internal(t);
        }

        return true;    /* continue the walk */
}

/** Kill all tasks except the current task. */
void task_done(void)
{
        unsigned tasks_left;

        do { /* Repeat until there are any tasks except TASK */
                /* Messing with task structures, avoid deadlock */
#ifdef CONFIG_DEBUG
                printf("Killing tasks... ");
#endif
                ipl_t ipl = interrupts_disable();
                spinlock_lock(&tasks_lock);
                tasks_left = 0;
                avltree_walk(&tasks_tree, task_done_walker, &tasks_left);
                spinlock_unlock(&tasks_lock);
                interrupts_restore(ipl);
                thread_sleep(1);
#ifdef CONFIG_DEBUG
                printf("\n");
#endif
        } while (tasks_left);
}

/** Create new task with no threads.
 *
 * @param as            Task's address space.
 * @param name          Symbolic name (a copy is made).
 *
 * @return              New task's structure.
 *
 */
task_t *task_create(as_t *as, char *name)
{
        ipl_t ipl;
        task_t *ta;
        int i;
        
        ta = (task_t *) slab_alloc(task_slab, 0);

        task_create_arch(ta);

        spinlock_initialize(&ta->lock, "task_ta_lock");
        list_initialize(&ta->th_head);
        ta->as = as;

        memcpy(ta->name, name, TASK_NAME_BUFLEN);
        ta->name[TASK_NAME_BUFLEN - 1] = 0;

        atomic_set(&ta->refcount, 0);
        atomic_set(&ta->lifecount, 0);
        ta->context = CONTEXT;

        ta->capabilities = 0;
        ta->cycles = 0;

#ifdef CONFIG_UDEBUG
        /* Init debugging stuff */
        udebug_task_init(&ta->udebug);

        /* Init kbox stuff */
        ipc_answerbox_init(&ta->kb.box, ta);
        ta->kb.thread = NULL;
        mutex_initialize(&ta->kb.cleanup_lock, MUTEX_PASSIVE);
        ta->kb.finished = false;
#endif

        ipc_answerbox_init(&ta->answerbox, ta);
        for (i = 0; i < IPC_MAX_PHONES; i++)
                ipc_phone_init(&ta->phones[i]);
        if ((ipc_phone_0) && (context_check(ipc_phone_0->task->context,
            ta->context)))
                ipc_phone_connect(&ta->phones[0], ipc_phone_0);
        atomic_set(&ta->active_calls, 0);
        list_initialize(&ta->sync_box_head);

        mutex_initialize(&ta->futexes_lock, MUTEX_PASSIVE);
        btree_create(&ta->futexes);
        
        ipl = interrupts_disable();

        /*
         * Increment address space reference count.
         */
        atomic_inc(&as->refcount);

        spinlock_lock(&tasks_lock);
        ta->taskid = ++task_counter;
        avltree_node_initialize(&ta->tasks_tree_node);
        ta->tasks_tree_node.key = ta->taskid; 
        avltree_insert(&tasks_tree, &ta->tasks_tree_node);
        spinlock_unlock(&tasks_lock);
        interrupts_restore(ipl);
        
        return ta;
}

/** Destroy task.
 *
 * @param t             Task to be destroyed.
 */
void task_destroy(task_t *t)
{
        /*
         * Remove the task from the task B+tree.
         */
        spinlock_lock(&tasks_lock);
        avltree_delete(&tasks_tree, &t->tasks_tree_node);
        spinlock_unlock(&tasks_lock);

        /*
         * Perform architecture specific task destruction.
         */
        task_destroy_arch(t);

        /*
         * Free up dynamically allocated state.
         */
        btree_destroy(&t->futexes);

        /*
         * Drop our reference to the address space.
         */
        if (atomic_predec(&t->as->refcount) == 0) 
                as_destroy(t->as);
        
        slab_free(task_slab, t);
        TASK = NULL;
}

/** Syscall for reading task ID from userspace.
 *
 * @param               uspace_task_id userspace address of 8-byte buffer
 *                      where to store current task ID.
 *
 * @return              Zero on success or an error code from @ref errno.h.
 */
unative_t sys_task_get_id(task_id_t *uspace_task_id)
{
        /*
         * No need to acquire lock on TASK because taskid remains constant for
         * the lifespan of the task.
         */
        return (unative_t) copy_to_uspace(uspace_task_id, &TASK->taskid,
            sizeof(TASK->taskid));
}

/** Syscall for setting the task name.
 *
 * The name simplifies identifying the task in the task list.
 *
 * @param name  The new name for the task. (typically the same
 *              as the command used to execute it).
 *
 * @return 0 on success or an error code from @ref errno.h.
 */
unative_t sys_task_set_name(const char *uspace_name, size_t name_len)
{
        int rc;
        char namebuf[TASK_NAME_BUFLEN];

        /* Cap length of name and copy it from userspace. */

        if (name_len > TASK_NAME_BUFLEN - 1)
                name_len = TASK_NAME_BUFLEN - 1;

        rc = copy_from_uspace(namebuf, uspace_name, name_len);
        if (rc != 0)
                return (unative_t) rc;

        namebuf[name_len] = '\0';
        str_cpy(TASK->name, TASK_NAME_BUFLEN, namebuf);

        return EOK;
}

/** Find task structure corresponding to task ID.
 *
 * The tasks_lock must be already held by the caller of this function and
 * interrupts must be disabled.
 *
 * @param id            Task ID.
 *
 * @return              Task structure address or NULL if there is no such task
 *                      ID.
 */
task_t *task_find_by_id(task_id_t id) { avltree_node_t *node;
        
        node = avltree_search(&tasks_tree, (avltree_key_t) id);

        if (node)
                return avltree_get_instance(node, task_t, tasks_tree_node); 
        return NULL;
}

/** Get accounting data of given task.
 *
 * Note that task lock of 't' must be already held and interrupts must be
 * already disabled.
 *
 * @param t             Pointer to thread.
 *
 * @return              Number of cycles used by the task and all its threads
 *                      so far.
 */
uint64_t task_get_accounting(task_t *t)
{
        /* Accumulated value of task */
        uint64_t ret = t->cycles;
        
        /* Current values of threads */
        link_t *cur;
        for (cur = t->th_head.next; cur != &t->th_head; cur = cur->next) {
                thread_t *thr = list_get_instance(cur, thread_t, th_link);
                
                spinlock_lock(&thr->lock);
                /* Process only counted threads */
                if (!thr->uncounted) {
                        if (thr == THREAD) {
                                /* Update accounting of current thread */
                                thread_update_accounting();
                        } 
                        ret += thr->cycles;
                }
                spinlock_unlock(&thr->lock);
        }
        
        return ret;
}

static void task_kill_internal(task_t *ta)
{
        link_t *cur;

        /*
         * Interrupt all threads.
         */
        spinlock_lock(&ta->lock);
        for (cur = ta->th_head.next; cur != &ta->th_head; cur = cur->next) {
                thread_t *thr;
                bool sleeping = false;
                
                thr = list_get_instance(cur, thread_t, th_link);
                
                spinlock_lock(&thr->lock);
                thr->interrupted = true;
                if (thr->state == Sleeping)
                        sleeping = true;
                spinlock_unlock(&thr->lock);
                
                if (sleeping)
                        waitq_interrupt_sleep(thr);
        }
        spinlock_unlock(&ta->lock);
}

/** Kill task.
 *
 * This function is idempotent.
 * It signals all the task's threads to bail it out.
 *
 * @param id            ID of the task to be killed.
 *
 * @return              Zero on success or an error code from errno.h.
 */
int task_kill(task_id_t id)
{
        ipl_t ipl;
        task_t *ta;

        if (id == 1)
                return EPERM;
        
        ipl = interrupts_disable();
        spinlock_lock(&tasks_lock);
        if (!(ta = task_find_by_id(id))) {
                spinlock_unlock(&tasks_lock);
                interrupts_restore(ipl);
                return ENOENT;
        }
        task_kill_internal(ta);
        spinlock_unlock(&tasks_lock);
        interrupts_restore(ipl);
        return 0;
}

static bool task_print_walker(avltree_node_t *node, void *arg)
{
        task_t *t = avltree_get_instance(node, task_t, tasks_tree_node);
        int j;
                
        spinlock_lock(&t->lock);
                        
        uint64_t cycles;
        char suffix;
        order(task_get_accounting(t), &cycles, &suffix);

#ifdef __32_BITS__      
        printf("%-6" PRIu64 " %-12s %-3" PRIu32 " %10p %10p %9" PRIu64
            "%c %7ld %6ld", t->taskid, t->name, t->context, t, t->as, cycles,
            suffix, atomic_get(&t->refcount), atomic_get(&t->active_calls));
#endif

#ifdef __64_BITS__
        printf("%-6" PRIu64 " %-12s %-3" PRIu32 " %18p %18p %9" PRIu64
            "%c %7ld %6ld", t->taskid, t->name, t->context, t, t->as, cycles,
            suffix, atomic_get(&t->refcount), atomic_get(&t->active_calls));
#endif

        for (j = 0; j < IPC_MAX_PHONES; j++) {
                if (t->phones[j].callee)
                        printf(" %d:%p", j, t->phones[j].callee);
        }
        printf("\n");
                        
        spinlock_unlock(&t->lock);
        return true;
}

/** Print task list */
void task_print_list(void)
{
        ipl_t ipl;
        
        /* Messing with task structures, avoid deadlock */
        ipl = interrupts_disable();
        spinlock_lock(&tasks_lock);

#ifdef __32_BITS__      
        printf("taskid name         ctx address    as         "
            "cycles     threads calls  callee\n");
        printf("------ ------------ --- ---------- ---------- "
            "---------- ------- ------ ------>\n");
#endif

#ifdef __64_BITS__
        printf("taskid name         ctx address            as                 "
            "cycles     threads calls  callee\n");
        printf("------ ------------ --- ------------------ ------------------ "
            "---------- ------- ------ ------>\n");
#endif

        avltree_walk(&tasks_tree, task_print_walker, NULL);

        spinlock_unlock(&tasks_lock);
        interrupts_restore(ipl);
}

/** @}
 */