source: mainline/kernel/generic/src/proc/thread.c@ ff3a34b

/*
 * 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       Thread management functions.
 */

#include <proc/scheduler.h>
#include <proc/thread.h>
#include <proc/task.h>
#include <proc/uarg.h>
#include <mm/frame.h>
#include <mm/page.h>
#include <arch/asm.h>
#include <arch/cycle.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 <adt/btree.h>
#include <adt/list.h>
#include <time/clock.h>
#include <time/timeout.h>
#include <config.h>
#include <arch/interrupt.h>
#include <smp/ipi.h>
#include <arch/faddr.h>
#include <atomic.h>
#include <memstr.h>
#include <print.h>
#include <mm/slab.h>
#include <debug.h>
#include <main/uinit.h>
#include <syscall/copy.h>
#include <errno.h>


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

/** Lock protecting the threads_btree B+tree.
 *
 * For locking rules, see declaration thereof.
 */
SPINLOCK_INITIALIZE(threads_lock);

/** B+tree of all threads.
 *
 * When a thread is found in the threads_btree B+tree, it is guaranteed to
 * exist as long as the threads_lock is held.
 */
btree_t threads_btree;          

SPINLOCK_INITIALIZE(tidlock);
thread_id_t last_tid = 0;

static slab_cache_t *thread_slab;
#ifdef ARCH_HAS_FPU
slab_cache_t *fpu_context_slab;
#endif

/** 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;
        THREAD->last_cycle = get_cycle();

        /* This is where each thread wakes up after its creation */
        spinlock_unlock(&THREAD->lock);
        interrupts_enable();

        f(arg);
        
        /* Accumulate accounting to the task */
        ipl_t ipl = interrupts_disable();
        
        spinlock_lock(&THREAD->lock);
        if (!THREAD->uncounted) {
                thread_update_accounting();
                uint64_t cycles = THREAD->cycles;
                THREAD->cycles = 0;
                spinlock_unlock(&THREAD->lock);
                
                spinlock_lock(&TASK->lock);
                TASK->cycles += cycles;
                spinlock_unlock(&TASK->lock);
        } else
                spinlock_unlock(&THREAD->lock);
        
        interrupts_restore(ipl);
        
        thread_exit();
        /* not reached */
}

/** Initialization and allocation for thread_t structure */
static int thr_constructor(void *obj, int kmflags)
{
        thread_t *t = (thread_t *) obj;

        spinlock_initialize(&t->lock, "thread_t_lock");
        link_initialize(&t->rq_link);
        link_initialize(&t->wq_link);
        link_initialize(&t->th_link);

        /* call the architecture-specific part of the constructor */
        thr_constructor_arch(t);
        
#ifdef ARCH_HAS_FPU
#ifdef CONFIG_FPU_LAZY
        t->saved_fpu_context = NULL;
#else
        t->saved_fpu_context = slab_alloc(fpu_context_slab, kmflags);
        if (!t->saved_fpu_context)
                return -1;
#endif
#endif  

        t->kstack = (uint8_t *) frame_alloc(STACK_FRAMES, FRAME_KA | kmflags);
        if (!t->kstack) {
#ifdef ARCH_HAS_FPU
                if (t->saved_fpu_context)
                        slab_free(fpu_context_slab, t->saved_fpu_context);
#endif
                return -1;
        }

        return 0;
}

/** Destruction of thread_t object */
static int thr_destructor(void *obj)
{
        thread_t *t = (thread_t *) obj;

        /* call the architecture-specific part of the destructor */
        thr_destructor_arch(t);

        frame_free(KA2PA(t->kstack));
#ifdef ARCH_HAS_FPU
        if (t->saved_fpu_context)
                slab_free(fpu_context_slab, t->saved_fpu_context);
#endif
        return 1; /* One page freed */
}

/** Initialize threads
 *
 * Initialize kernel threads support.
 *
 */
void thread_init(void)
{
        THREAD = NULL;
        atomic_set(&nrdy,0);
        thread_slab = slab_cache_create("thread_slab", sizeof(thread_t), 0,
            thr_constructor, thr_destructor, 0);

#ifdef ARCH_HAS_FPU
        fpu_context_slab = slab_cache_create("fpu_slab", sizeof(fpu_context_t),
            FPU_CONTEXT_ALIGN, NULL, NULL, 0);
#endif

        btree_create(&threads_btree);
}

/** 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);

        ASSERT(!(t->state == Ready));

        i = (t->priority < RQ_COUNT - 1) ? ++t->priority : t->priority;
        
        cpu = CPU;
        if (t->flags & THREAD_FLAG_WIRED) {
                ASSERT(t->cpu != NULL);
                cpu = t->cpu;
        }
        t->state = Ready;
        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;
        atomic_inc(&cpu->nrdy);

        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.
 * @param name      Symbolic name.
 * @param uncounted Thread's accounting doesn't affect accumulated task
 *                  accounting.
 *
 * @return New thread's structure on success, NULL on failure.
 *
 */
thread_t *thread_create(void (* func)(void *), void *arg, task_t *task,
    int flags, char *name, bool uncounted)
{
        thread_t *t;
        ipl_t ipl;
        
        t = (thread_t *) slab_alloc(thread_slab, 0);
        if (!t)
                return NULL;
        
        /* Not needed, but good for debugging */
        memsetb((uintptr_t) t->kstack, THREAD_STACK_SIZE * 1 << STACK_FRAMES,
            0);
        
        ipl = interrupts_disable();
        spinlock_lock(&tidlock);
        t->tid = ++last_tid;
        spinlock_unlock(&tidlock);
        interrupts_restore(ipl);
        
        context_save(&t->saved_context);
        context_set(&t->saved_context, FADDR(cushion), (uintptr_t) t->kstack,
            THREAD_STACK_SIZE);
        
        the_initialize((the_t *) t->kstack);
        
        ipl = interrupts_disable();
        t->saved_context.ipl = interrupts_read();
        interrupts_restore(ipl);
        
        memcpy(t->name, name, THREAD_NAME_BUFLEN);
        
        t->thread_code = func;
        t->thread_arg = arg;
        t->ticks = -1;
        t->cycles = 0;
        t->uncounted = uncounted;
        t->priority = -1;               /* start in rq[0] */
        t->cpu = NULL;
        t->flags = flags;
        t->state = Entering;
        t->call_me = NULL;
        t->call_me_with = NULL;
        
        timeout_initialize(&t->sleep_timeout);
        t->sleep_interruptible = false;
        t->sleep_queue = NULL;
        t->timeout_pending = 0;

        t->in_copy_from_uspace = false;
        t->in_copy_to_uspace = false;

        t->interrupted = false; 
        t->join_type = None;
        t->detached = false;
        waitq_initialize(&t->join_wq);
        
        t->rwlock_holder_type = RWLOCK_NONE;
                
        t->task = task;
        
        t->fpu_context_exists = 0;
        t->fpu_context_engaged = 0;

        /* might depend on previous initialization */
        thread_create_arch(t);  

        ipl = interrupts_disable();      
        spinlock_lock(&task->lock);
        if (!task->accept_new_threads) {
                spinlock_unlock(&task->lock);
                slab_free(thread_slab, t);
                interrupts_restore(ipl);
                return NULL;
        } else {
                /*
                 * Bump the reference count so that this task cannot be
                 * destroyed while the new thread is being attached to it.
                 */
                task->refcount++;
        }
        spinlock_unlock(&task->lock);
        interrupts_restore(ipl);

        if (!(flags & THREAD_FLAG_NOATTACH))
                thread_attach(t, task);

        return t;
}

/** Destroy thread memory structure
 *
 * Detach thread from all queues, cpus etc. and destroy it.
 *
 * Assume thread->lock is held!!
 */
void thread_destroy(thread_t *t)
{
        bool destroy_task = false;

        ASSERT(t->state == Exiting || t->state == Undead);
        ASSERT(t->task);
        ASSERT(t->cpu);

        spinlock_lock(&t->cpu->lock);
        if (t->cpu->fpu_owner == t)
                t->cpu->fpu_owner = NULL;
        spinlock_unlock(&t->cpu->lock);

        spinlock_unlock(&t->lock);

        spinlock_lock(&threads_lock);
        btree_remove(&threads_btree, (btree_key_t) ((uintptr_t ) t), NULL);
        spinlock_unlock(&threads_lock);

        /*
         * Detach from the containing task.
         */
        spinlock_lock(&t->task->lock);
        list_remove(&t->th_link);
        if (--t->task->refcount == 0) {
                t->task->accept_new_threads = false;
                destroy_task = true;
        }
        spinlock_unlock(&t->task->lock);        
        
        if (destroy_task)
                task_destroy(t->task);
        
        /*
         * If the thread had a userspace context, free up its kernel_uarg
         * structure.
         */
        if (t->flags & THREAD_FLAG_USPACE) {
                ASSERT(t->thread_arg);
                free(t->thread_arg);
        }

        slab_free(thread_slab, t);
}

/** Make the thread visible to the system.
 *
 * Attach the thread structure to the current task and make it visible in the
 * threads_btree.
 *
 * @param t     Thread to be attached to the task.
 * @param task  Task to which the thread is to be attached.
 */
void thread_attach(thread_t *t, task_t *task)
{
        ipl_t ipl;

        /*
         * Attach to the current task.
         */
        ipl = interrupts_disable();      
        spinlock_lock(&task->lock);
        ASSERT(task->refcount);
        list_append(&t->th_link, &task->th_head);
        if (task->refcount == 1)
                task->main_thread = t;
        spinlock_unlock(&task->lock);

        /*
         * Register this thread in the system-wide list.
         */
        spinlock_lock(&threads_lock);
        btree_insert(&threads_btree, (btree_key_t) ((uintptr_t) t), (void *) t,
            NULL);
        spinlock_unlock(&threads_lock);
        
        interrupts_restore(ipl);
}

/** Terminate thread.
 *
 * 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();

        /* Not reached */
        while (1)
                ;
}


/** Thread sleep
 *
 * Suspend execution of the current thread.
 *
 * @param sec Number of seconds to sleep.
 *
 */
void thread_sleep(uint32_t sec)
{
        thread_usleep(sec * 1000000);
}

/** Wait for another thread to exit.
 *
 * @param t Thread to join on exit.
 * @param usec Timeout in microseconds.
 * @param flags Mode of operation.
 *
 * @return An error code from errno.h or an error code from synch.h.
 */
int thread_join_timeout(thread_t *t, uint32_t usec, int flags)
{
        ipl_t ipl;
        int rc;

        if (t == THREAD)
                return EINVAL;

        /*
         * Since thread join can only be called once on an undetached thread,
         * the thread pointer is guaranteed to be still valid.
         */
        
        ipl = interrupts_disable();
        spinlock_lock(&t->lock);
        ASSERT(!t->detached);
        spinlock_unlock(&t->lock);
        interrupts_restore(ipl);
        
        rc = waitq_sleep_timeout(&t->join_wq, usec, flags);
        
        return rc;      
}

/** Detach thread.
 *
 * Mark the thread as detached, if the thread is already in the Undead state,
 * deallocate its resources.
 *
 * @param t Thread to be detached.
 */
void thread_detach(thread_t *t)
{
        ipl_t ipl;

        /*
         * Since the thread is expected not to be already detached,
         * pointer to it must be still valid.
         */
        ipl = interrupts_disable();
        spinlock_lock(&t->lock);
        ASSERT(!t->detached);
        if (t->state == Undead) {
                thread_destroy(t);      /* unlocks &t->lock */
                interrupts_restore(ipl);
                return;
        } else {
                t->detached = true;
        }
        spinlock_unlock(&t->lock);
        interrupts_restore(ipl);
}

/** Thread usleep
 *
 * Suspend execution of the current thread.
 *
 * @param usec Number of microseconds to sleep.
 *
 */     
void thread_usleep(uint32_t usec)
{
        waitq_t wq;
                                  
        waitq_initialize(&wq);

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

/** Print list of threads debug info */
void thread_print_list(void)
{
        link_t *cur;
        ipl_t ipl;
        
        /* Messing with thread structures, avoid deadlock */
        ipl = interrupts_disable();
        spinlock_lock(&threads_lock);
        
        printf("tid    name       address    state    task       ctx code    "
            "   stack      cycles     cpu  kstack     waitqueue\n");
        printf("------ ---------- ---------- -------- ---------- --- --------"
            "-- ---------- ---------- ---- ---------- ----------\n");

        for (cur = threads_btree.leaf_head.next;
            cur != &threads_btree.leaf_head; cur = cur->next) {
                btree_node_t *node;
                unsigned int i;

                node = list_get_instance(cur, btree_node_t, leaf_link);
                for (i = 0; i < node->keys; i++) {
                        thread_t *t;
                
                        t = (thread_t *) node->value[i];
                        
                        uint64_t cycles;
                        char suffix;
                        order(t->cycles, &cycles, &suffix);
                        
                        printf("%-6llu %-10s %#10zx %-8s %#10zx %-3ld %#10zx "
                            "%#10zx %9llu%c ", t->tid, t->name, t,
                            thread_states[t->state], t->task, t->task->context,
                            t->thread_code, t->kstack, cycles, suffix);
                        
                        if (t->cpu)
                                printf("%-4zd", t->cpu->id);
                        else
                                printf("none");
                        
                        if (t->state == Sleeping)
                                printf(" %#10zx %#10zx", t->kstack,
                                    t->sleep_queue);
                        
                        printf("\n");
                }
        }

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

/** Check whether thread exists.
 *
 * Note that threads_lock must be already held and
 * interrupts must be already disabled.
 *
 * @param t Pointer to thread.
 *
 * @return True if thread t is known to the system, false otherwise.
 */
bool thread_exists(thread_t *t)
{
        btree_node_t *leaf;
        
        return btree_search(&threads_btree, (btree_key_t) ((uintptr_t) t),
            &leaf) != NULL;
}


/** Update accounting of current thread.
 *
 * Note that thread_lock on THREAD must be already held and
 * interrupts must be already disabled.
 *
 */
void thread_update_accounting(void)
{
        uint64_t time = get_cycle();
        THREAD->cycles += time - THREAD->last_cycle;
        THREAD->last_cycle = time;
}

/** Process syscall to create new thread.
 *
 */
unative_t sys_thread_create(uspace_arg_t *uspace_uarg, char *uspace_name,
    thread_id_t *uspace_thread_id)
{
        thread_t *t;
        char namebuf[THREAD_NAME_BUFLEN];
        uspace_arg_t *kernel_uarg;
        int rc;

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

        kernel_uarg = (uspace_arg_t *) malloc(sizeof(uspace_arg_t), 0); 
        rc = copy_from_uspace(kernel_uarg, uspace_uarg, sizeof(uspace_arg_t));
        if (rc != 0) {
                free(kernel_uarg);
                return (unative_t) rc;
        }

        t = thread_create(uinit, kernel_uarg, TASK,
            THREAD_FLAG_USPACE | THREAD_FLAG_NOATTACH, namebuf, false);
        if (t) {
                if (uspace_thread_id != NULL) {
                        int rc;

                        rc = copy_to_uspace(uspace_thread_id, &t->tid,
                            sizeof(t->tid));
                        if (rc != 0) {
                                ipl_t ipl;

                                /*
                                 * We have encountered a failure, but the thread
                                 * has already been created. We need to undo its
                                 * creation now.
                                 */

                                /*
                                 * The new thread structure is initialized,
                                 * but is still not visible to the system.
                                 * We can safely deallocate it.
                                 */
                                slab_free(thread_slab, t);
                                free(kernel_uarg);

                                /*
                                 * Now we need to decrement the task reference
                                 * counter. Because we are running within the
                                 * same task, thread t is not the last thread
                                 * in the task, so it is safe to merely
                                 * decrement the counter.
                                 */
                                ipl = interrupts_disable();
                                spinlock_lock(&TASK->lock);
                                TASK->refcount--;
                                spinlock_unlock(&TASK->lock);
                                interrupts_restore(ipl);

                                return (unative_t) rc;
                         }
                }
                thread_attach(t, TASK);
                thread_ready(t);

                return 0;
        } else
                free(kernel_uarg);

        return (unative_t) ENOMEM;
}

/** Process syscall to terminate thread.
 *
 */
unative_t sys_thread_exit(int uspace_status)
{
        thread_exit();
        /* Unreachable */
        return 0;
}

/** Syscall for getting TID.
 *
 * @param uspace_thread_id Userspace address of 8-byte buffer where to store
 * current thread ID.
 *
 * @return 0 on success or an error code from @ref errno.h.
 */
unative_t sys_thread_get_id(thread_id_t *uspace_thread_id)
{
        /*
         * No need to acquire lock on THREAD because tid
         * remains constant for the lifespan of the thread.
         */
        return (unative_t) copy_to_uspace(uspace_thread_id, &THREAD->tid,
            sizeof(THREAD->tid));
}

/** @}
 */