WebSVN – HelenOS – Diff – /branches/tracing/kernel/generic/src/ipc/ipc.c


/*
 * Copyright (c) 2006 Ondrej Palkovsky
 * 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 genericipc
 * @{
 */
/** @file
 */
 
/* Lock ordering
 *
 * First the answerbox, then the phone.
 */
 
#include <synch/spinlock.h>
#include <synch/waitq.h>
#include <synch/synch.h>
#include <ipc/ipc.h>
#include <errno.h>
#include <mm/slab.h>
#include <arch.h>
#include <proc/task.h>
#include <memstr.h>
#include <debug.h>
 
#include <print.h>
#include <console/klog.h>
#include <proc/thread.h>
#include <arch/interrupt.h>
#include <ipc/irq.h>
 
/** Open channel that is assigned automatically to new tasks */
answerbox_t *ipc_phone_0 = NULL;
 
static slab_cache_t *ipc_call_slab;
 
/** Initialize a call structure.
 *
 * @param call      Call structure to be initialized.
 */
static void _ipc_call_init(call_t *call)
{
    memsetb((uintptr_t) call, sizeof(*call), 0);
    call->callerbox = &TASK->answerbox;
    call->sender = TASK;
    call->buffer = NULL;
}
 
/** Allocate and initialize a call structure.
 *
 * The call is initialized, so that the reply will be directed to
 * TASK->answerbox.
 *
 * @param flags     Parameters for slab_alloc (e.g FRAME_ATOMIC).
 *
 * @return      If flags permit it, return NULL, or initialized kernel
 *          call structure.
 */
call_t *ipc_call_alloc(int flags)
{
    call_t *call;
 
    call = slab_alloc(ipc_call_slab, flags);
    _ipc_call_init(call);
 
    return call;
}
 
/** Initialize a statically allocated call structure.
 *
 * @param call      Statically allocated kernel call structure to be
 *          initialized.
 */
void ipc_call_static_init(call_t *call)
{
    _ipc_call_init(call);
    call->flags |= IPC_CALL_STATIC_ALLOC;
}
 
/** Deallocate a call structure.
 *
 * @param call      Call structure to be freed.
 */
void ipc_call_free(call_t *call)
{
    ASSERT(!(call->flags & IPC_CALL_STATIC_ALLOC));
    /* Check to see if we have data in the IPC_M_DATA_SEND buffer. */
    if (call->buffer)
        free(call->buffer);
    slab_free(ipc_call_slab, call);
}
 
/** Initialize an answerbox structure.
 *
 * @param box       Answerbox structure to be initialized.
 * @param task      Task to which the answerbox belongs.
 */
void ipc_answerbox_init(answerbox_t *box, task_t *task)
{
    spinlock_initialize(&box->lock, "ipc_box_lock");
    spinlock_initialize(&box->irq_lock, "ipc_box_irqlock");
    waitq_initialize(&box->wq);
    list_initialize(&box->connected_phones);
    list_initialize(&box->calls);
    list_initialize(&box->dispatched_calls);
    list_initialize(&box->answers);
    list_initialize(&box->irq_notifs);
    list_initialize(&box->irq_head);
    box->task = task;
}
 
/** Connect a phone to an answerbox.
 *
 * @param phone     Initialized phone structure.
 * @param box       Initialized answerbox structure.
 */
void ipc_phone_connect(phone_t *phone, answerbox_t *box)
{
    spinlock_lock(&phone->lock);
 
    phone->state = IPC_PHONE_CONNECTED;
    phone->callee = box;
 
    spinlock_lock(&box->lock);
    list_append(&phone->link, &box->connected_phones);
    spinlock_unlock(&box->lock);
 
    spinlock_unlock(&phone->lock);
}
 
/** Initialize a phone structure.
 *
 * @param phone     Phone structure to be initialized.
 */
void ipc_phone_init(phone_t *phone)
{
    spinlock_initialize(&phone->lock, "phone_lock");
    phone->callee = NULL;
    phone->state = IPC_PHONE_FREE;
    atomic_set(&phone->active_calls, 0);
}
 
/** Helper function to facilitate synchronous calls.
 *
 * @param phone     Destination kernel phone structure.
 * @param request   Call structure with request.
 */
void ipc_call_sync(phone_t *phone, call_t *request)
{
    answerbox_t sync_box;
 
    ipc_answerbox_init(&sync_box, TASK);
 
    /* We will receive data in a special box. */
    request->callerbox = &sync_box;
 
    ipc_call(phone, request);
    ipc_wait_for_call(&sync_box, SYNCH_NO_TIMEOUT, SYNCH_FLAGS_NONE);
}
 
/** Answer a message which was not dispatched and is not listed in any queue.
 *
 * @param call      Call structure to be answered.
 */
static void _ipc_answer_free_call(call_t *call)
{
    answerbox_t *callerbox = call->callerbox;
 
    call->flags |= IPC_CALL_ANSWERED;
 
    spinlock_lock(&callerbox->lock);
    list_append(&call->link, &callerbox->answers);
    spinlock_unlock(&callerbox->lock);
    waitq_wakeup(&callerbox->wq, WAKEUP_FIRST);
}
 
/** Answer a message which is in a callee queue.
 *
 * @param box       Answerbox that is answering the message.
 * @param call      Modified request that is being sent back.
 */
void ipc_answer(answerbox_t *box, call_t *call)
{
    /* Remove from active box */
    spinlock_lock(&box->lock);
    list_remove(&call->link);
    spinlock_unlock(&box->lock);
    /* Send back answer */
    _ipc_answer_free_call(call);
}
 
/** Simulate sending back a message.
 *
 * Most errors are better handled by forming a normal backward
 * message and sending it as a normal answer.
 *
 * @param phone     Phone structure the call should appear to come from.
 * @param call      Call structure to be answered.
 * @param err       Return value to be used for the answer.
 */
void ipc_backsend_err(phone_t *phone, call_t *call, unative_t err)
{
    call->data.phone = phone;
    atomic_inc(&phone->active_calls);
    IPC_SET_RETVAL(call->data, err);
    _ipc_answer_free_call(call);
}
 
/** Unsafe unchecking version of ipc_call.
 *
 * @param phone     Phone structure the call comes from.
 * @param box       Destination answerbox structure.
 * @param call      Call structure with request.
 */
static void _ipc_call(phone_t *phone, answerbox_t *box, call_t *call)
{
    if (!(call->flags & IPC_CALL_FORWARDED)) {
        atomic_inc(&phone->active_calls);
        call->data.phone = phone;
    }
 
    spinlock_lock(&box->lock);
    list_append(&call->link, &box->calls);
    spinlock_unlock(&box->lock);
    waitq_wakeup(&box->wq, WAKEUP_FIRST);
}
 
/** Send an asynchronous request using a phone to an answerbox.
 *
 * @param phone     Phone structure the call comes from and which is
 *          connected to the destination answerbox.
 * @param call      Call structure with request.
 *
 * @return      Return 0 on success, ENOENT on error.
 */
int ipc_call(phone_t *phone, call_t *call)
{
    answerbox_t *box;
 
    spinlock_lock(&phone->lock);
    if (phone->state != IPC_PHONE_CONNECTED) {
        spinlock_unlock(&phone->lock);
        if (call->flags & IPC_CALL_FORWARDED) {
            IPC_SET_RETVAL(call->data, EFORWARD);
            _ipc_answer_free_call(call);
        } else {
            if (phone->state == IPC_PHONE_HUNGUP)
                ipc_backsend_err(phone, call, EHANGUP);
            else
                ipc_backsend_err(phone, call, ENOENT);
        }
        return ENOENT;
    }
    box = phone->callee;
    _ipc_call(phone, box, call);
   
    spinlock_unlock(&phone->lock);
    return 0;
}
 
/** Disconnect phone from answerbox.
 *
 * This call leaves the phone in the HUNGUP state. The change to 'free' is done
 * lazily later.
 *
 * @param phone     Phone structure to be hung up.
 *              
 * @return      Return 0 if the phone is disconnected.
 *          Return -1 if the phone was already disconnected.
 */
int ipc_phone_hangup(phone_t *phone)
{
    answerbox_t *box;
    call_t *call;
   
    spinlock_lock(&phone->lock);
    if (phone->state == IPC_PHONE_FREE ||
        phone->state == IPC_PHONE_HUNGUP ||
        phone->state == IPC_PHONE_CONNECTING) {
        spinlock_unlock(&phone->lock);
        return -1;
    }
    box = phone->callee;
    if (phone->state != IPC_PHONE_SLAMMED) {
        /* Remove myself from answerbox */
        spinlock_lock(&box->lock);
        list_remove(&phone->link);
        spinlock_unlock(&box->lock);
 
        if (phone->state != IPC_PHONE_SLAMMED) {
            call = ipc_call_alloc(0);
            IPC_SET_METHOD(call->data, IPC_M_PHONE_HUNGUP);
            call->flags |= IPC_CALL_DISCARD_ANSWER;
            _ipc_call(phone, box, call);
        }
    }
 
    phone->state = IPC_PHONE_HUNGUP;
    spinlock_unlock(&phone->lock);
 
    return 0;
}
 
/** Forwards call from one answerbox to another one.
 *
 * @param call      Call structure to be redirected.
 * @param newphone  Phone structure to target answerbox.
 * @param oldbox    Old answerbox structure.
 * @param mode      Flags that specify mode of the forward operation.
 *
 * @return      Return 0 if forwarding succeeded or an error code if
 *          there was error.
 *
 * The return value serves only as an information for the forwarder,
 * the original caller is notified automatically with EFORWARD.
 */
int ipc_forward(call_t *call, phone_t *newphone, answerbox_t *oldbox, int mode)
{
    spinlock_lock(&oldbox->lock);
    list_remove(&call->link);
    spinlock_unlock(&oldbox->lock);
 
    if (mode & IPC_FF_ROUTE_FROM_ME)
        call->data.phone = newphone;
 
    return ipc_call(newphone, call);
}
 
 
/** Wait for a phone call.
 *
 * @param box       Answerbox expecting the call.
 * @param usec      Timeout in microseconds. See documentation for
 *          waitq_sleep_timeout() for decription of its special
 *          meaning.
 * @param flags     Select mode of sleep operation. See documentation for
 *          waitq_sleep_timeout() for description of its special
 *          meaning.
 * @return      Recived call structure or NULL.
 *
 * To distinguish between a call and an answer, have a look at call->flags.
 */
call_t *ipc_wait_for_call(answerbox_t *box, uint32_t usec, int flags)
{
    call_t *request;
    ipl_t ipl;
    int rc;
 
restart:
    rc = waitq_sleep_timeout(&box->wq, usec, flags);
    if (SYNCH_FAILED(rc))
        return NULL;
   
    spinlock_lock(&box->lock);
    if (!list_empty(&box->irq_notifs)) {
        ipl = interrupts_disable();
        spinlock_lock(&box->irq_lock);
 
        request = list_get_instance(box->irq_notifs.next, call_t, link);
        list_remove(&request->link);
 
        spinlock_unlock(&box->irq_lock);
        interrupts_restore(ipl);
    } else if (!list_empty(&box->answers)) {
        /* Handle asynchronous answers */
        request = list_get_instance(box->answers.next, call_t, link);
        list_remove(&request->link);
        atomic_dec(&request->data.phone->active_calls);
    } else if (!list_empty(&box->calls)) {
        /* Handle requests */
        request = list_get_instance(box->calls.next, call_t, link);
        list_remove(&request->link);
        /* Append request to dispatch queue */
        list_append(&request->link, &box->dispatched_calls);
    } else {
        /* This can happen regularly after ipc_cleanup */
        spinlock_unlock(&box->lock);
        goto restart;
    }
    spinlock_unlock(&box->lock);
    return request;
}
 
/** Answer all calls from list with EHANGUP answer.
 *
 * @param lst       Head of the list to be cleaned up.
 */
static void ipc_cleanup_call_list(link_t *lst)
{
    call_t *call;
 
    while (!list_empty(lst)) {
        call = list_get_instance(lst->next, call_t, link);
        if (call->buffer)
            free(call->buffer);
        list_remove(&call->link);
 
        IPC_SET_RETVAL(call->data, EHANGUP);
        _ipc_answer_free_call(call);
    }
}
 
/** Disconnects all phones connected to an answerbox.
 *
 * @param box       Answerbox to disconnect phones from.
 * @param notify_box    If true, the answerbox will get a hangup message for
 *          each disconnected phone.
 */
static void ipc_answerbox_slam_phones(answerbox_t *box, bool notify_box)
{
    phone_t *phone;
    DEADLOCK_PROBE_INIT(p_phonelck);
    ipl_t ipl;
    call_t *call;
 
    call = ipc_call_alloc(0);
 
    /* Disconnect all phones connected to our answerbox */
restart_phones:
    ipl = interrupts_disable();
    spinlock_lock(&box->lock);
    while (!list_empty(&box->connected_phones)) {
        phone = list_get_instance(box->connected_phones.next,
            phone_t, link);
        if (!spinlock_trylock(&phone->lock)) {
            spinlock_unlock(&box->lock);
            interrupts_restore(ipl);
            DEADLOCK_PROBE(p_phonelck, DEADLOCK_THRESHOLD);
            goto restart_phones;
        }
       
        /* Disconnect phone */
        ASSERT(phone->state == IPC_PHONE_CONNECTED);
 
        list_remove(&phone->link);
        phone->state = IPC_PHONE_SLAMMED;
 
        if (notify_box) {
            spinlock_unlock(&phone->lock);
            spinlock_unlock(&box->lock);
            interrupts_restore(ipl);
 
            /*
             * Send one message to the answerbox for each
             * phone. Used to make sure the kbox thread
             * wakes up after the last phone has been
             * disconnected.
             */
            IPC_SET_METHOD(call->data, IPC_M_PHONE_HUNGUP);
            call->flags |= IPC_CALL_DISCARD_ANSWER;
            _ipc_call(phone, box, call);
 
            /* Allocate another call in advance */
            call = ipc_call_alloc(0);
 
            /* Must start again */
            goto restart_phones;
        }
 
        spinlock_unlock(&phone->lock);
    }
 
    spinlock_unlock(&box->lock);
    interrupts_restore(ipl);
 
    /* Free unused call */
    if (call) ipc_call_free(call);
}
 
static void ipc_kbox_cleanup()
{
    ipl_t ipl;
    bool have_kb_thread;
 
    /* Only hold kb_cleanup_lock while setting kb_finished - this is enough */
    ipl = interrupts_disable();
    spinlock_lock(&TASK->kb_cleanup_lock);
 
    TASK->kb_finished = true;
 
    spinlock_unlock(&TASK->kb_cleanup_lock);
    interrupts_restore(ipl);
 
    have_kb_thread = (TASK->kb_thread != NULL);
 
    /* From now on nobody will try to connect phones or attach kbox threads */
 
    /*
     * Disconnect all phones connected to our kbox. Passing true for
     * notify_box causes a HANGUP message to be inserted for each
     * disconnected phone. This ensures the kbox thread is going to
     * wake up and terminate.
     */
    ipc_answerbox_slam_phones(&TASK->kernel_box, have_kb_thread);
   
    /* TODO: Wait for kbox thread to terminate */
    if (have_kb_thread) {
        klog_printf("ipc_kbox_cleanup - wait for kbox thread to finish");
        waitq_sleep(&TASK->kb_thread_shutdown_wq);
    }
 
    /* Answer all messages in 'calls' and 'dispatched_calls' queues */
    spinlock_lock(&TASK->kernel_box.lock);
    ipc_cleanup_call_list(&TASK->kernel_box.dispatched_calls);
    ipc_cleanup_call_list(&TASK->kernel_box.calls);
    spinlock_unlock(&TASK->kernel_box.lock);
}
 
 
/** Cleans up all IPC communication of the current task.
 *
 * Note: ipc_hangup sets returning answerbox to TASK->answerbox, you
 * have to change it as well if you want to cleanup other tasks than TASK.
 */
void ipc_cleanup(void)
{
    int i;
    call_t *call;
 
    /* Disconnect all our phones ('ipc_phone_hangup') */
    for (i = 0; i < IPC_MAX_PHONES; i++)
        ipc_phone_hangup(&TASK->phones[i]);
 
    /* Disconnect all connected irqs */
    ipc_irq_cleanup(&TASK->answerbox);
 
    /* Disconnect all phones connected to our regular answerbox */
    ipc_answerbox_slam_phones(&TASK->answerbox, false);
 
    /* Clean up kbox thread and communications */
    ipc_kbox_cleanup();
 
    /* Answer all messages in 'calls' and 'dispatched_calls' queues */
    spinlock_lock(&TASK->answerbox.lock);
    ipc_cleanup_call_list(&TASK->answerbox.dispatched_calls);
    ipc_cleanup_call_list(&TASK->answerbox.calls);
    spinlock_unlock(&TASK->answerbox.lock);
   
    /* Wait for all async answers to arrive */
    while (1) {
        /* Go through all phones, until all are FREE... */
        /* Locking not needed, no one else should modify
         * it, when we are in cleanup */
        for (i = 0; i < IPC_MAX_PHONES; i++) {
            if (TASK->phones[i].state == IPC_PHONE_HUNGUP &&
                atomic_get(&TASK->phones[i].active_calls) == 0)
                TASK->phones[i].state = IPC_PHONE_FREE;
           
            /* Just for sure, we might have had some
             * IPC_PHONE_CONNECTING phones */
            if (TASK->phones[i].state == IPC_PHONE_CONNECTED)
                ipc_phone_hangup(&TASK->phones[i]);
            /* If the hangup succeeded, it has sent a HANGUP
             * message, the IPC is now in HUNGUP state, we
             * wait for the reply to come */
           
            if (TASK->phones[i].state != IPC_PHONE_FREE)
                break;
        }
        /* Voila, got into cleanup */
        if (i == IPC_MAX_PHONES)
            break;
       
        call = ipc_wait_for_call(&TASK->answerbox, SYNCH_NO_TIMEOUT,
            SYNCH_FLAGS_NONE);
        ASSERT((call->flags & IPC_CALL_ANSWERED) ||
            (call->flags & IPC_CALL_NOTIF));
        ASSERT(!(call->flags & IPC_CALL_STATIC_ALLOC));
       
        atomic_dec(&TASK->active_calls);
        ipc_call_free(call);
    }
}
 
 
/** Initilize IPC subsystem */
void ipc_init(void)
{
    ipc_call_slab = slab_cache_create("ipc_call", sizeof(call_t), 0, NULL,
        NULL, 0);
}
 
 
/** List answerbox contents.
 *
 * @param taskid    Task ID.
 */
void ipc_print_task(task_id_t taskid)
{
    task_t *task;
    int i;
    call_t *call;
    link_t *tmp;
   
    spinlock_lock(&tasks_lock);
    task = task_find_by_id(taskid);
    if (task)
        spinlock_lock(&task->lock);
    spinlock_unlock(&tasks_lock);
    if (!task)
        return;
 
    /* Print opened phones & details */
    printf("PHONE:\n");
    for (i = 0; i < IPC_MAX_PHONES; i++) {
        spinlock_lock(&task->phones[i].lock);
        if (task->phones[i].state != IPC_PHONE_FREE) {
            printf("%d: ", i);
            switch (task->phones[i].state) {
            case IPC_PHONE_CONNECTING:
                printf("connecting ");
                break;
            case IPC_PHONE_CONNECTED:
                printf("connected to: %p ",
                       task->phones[i].callee);
                break;
            case IPC_PHONE_SLAMMED:
                printf("slammed by: %p ",
                       task->phones[i].callee);
                break;
            case IPC_PHONE_HUNGUP:
                printf("hung up - was: %p ",
                       task->phones[i].callee);
                break;
            default:
                break;
            }
            printf("active: %d\n",
                atomic_get(&task->phones[i].active_calls));
        }
        spinlock_unlock(&task->phones[i].lock);
    }
 
 
    /* Print answerbox - calls */
    spinlock_lock(&task->answerbox.lock);
    printf("ABOX - CALLS:\n");
    for (tmp = task->answerbox.calls.next; tmp != &task->answerbox.calls;
        tmp = tmp->next) {
        call = list_get_instance(tmp, call_t, link);
        printf("Callid: %p Srctask:%llu M:%d A1:%d A2:%d A3:%d "
            "A4:%d A5:%d Flags:%x\n", call, call->sender->taskid,
            IPC_GET_METHOD(call->data), IPC_GET_ARG1(call->data),
            IPC_GET_ARG2(call->data), IPC_GET_ARG3(call->data),
            IPC_GET_ARG4(call->data), IPC_GET_ARG5(call->data),
            call->flags);
    }
    /* Print answerbox - calls */
    printf("ABOX - DISPATCHED CALLS:\n");
    for (tmp=task->answerbox.dispatched_calls.next;
         tmp != &task->answerbox.dispatched_calls;
         tmp = tmp->next) {
        call = list_get_instance(tmp, call_t, link);
        printf("Callid: %p Srctask:%llu M:%d A1:%d A2:%d A3:%d "
            "A4:%d A5:%d Flags:%x\n", call, call->sender->taskid,
            IPC_GET_METHOD(call->data), IPC_GET_ARG1(call->data),
            IPC_GET_ARG2(call->data), IPC_GET_ARG3(call->data),
            IPC_GET_ARG4(call->data), IPC_GET_ARG5(call->data),
            call->flags);
    }
    /* Print answerbox - calls */
    printf("ABOX - ANSWERS:\n");
    for (tmp = task->answerbox.answers.next; tmp != &task->answerbox.answers;
        tmp = tmp->next) {
        call = list_get_instance(tmp, call_t, link);
        printf("Callid:%p M:%d A1:%d A2:%d A3:%d A4:%d A5:%d Flags:%x\n",
            call, IPC_GET_METHOD(call->data), IPC_GET_ARG1(call->data),
            IPC_GET_ARG2(call->data), IPC_GET_ARG3(call->data),
            IPC_GET_ARG4(call->data), IPC_GET_ARG5(call->data),
            call->flags);
    }
 
    spinlock_unlock(&task->answerbox.lock);
    spinlock_unlock(&task->lock);
}
 
#include <ipc/ipcrsc.h>
#include <console/klog.h>
#include <udebug/udebug_ipc.h>
 
static void kbox_thread_proc(void *arg)
{
    call_t *call;
    int method;
    bool done;
    ipl_t ipl;
 
    (void)arg;
    klog_printf("kbox_thread_proc()");
    done = false;
 
    while (!done) {
        //klog_printf("kbox: wait for call");
        call = ipc_wait_for_call(&TASK->kernel_box, SYNCH_NO_TIMEOUT,
            SYNCH_FLAGS_NONE);
 
        if (call != NULL) {
            method = IPC_GET_METHOD(call->data);
 
            if (method == IPC_M_DEBUG_ALL) {
                udebug_call_receive(call);
            }
 
            if (method == IPC_M_PHONE_HUNGUP) {
                klog_printf("kbox: handle hangup message");
 
                /* Was it our debugger, who hung up? */
                if (call->sender == TASK->udebug.debugger) {
                    /* Terminate debugging session (if any) */
                    klog_printf("kbox: terminate debug session");
                    ipl = interrupts_disable();
                    spinlock_lock(&TASK->lock);
                    udebug_task_cleanup(TASK);
                    spinlock_unlock(&TASK->lock);
                    interrupts_restore(ipl);
                } else {
                    klog_printf("kbox: was not debugger");
                }
 
                klog_printf("kbox: continue with hangup message");
                IPC_SET_RETVAL(call->data, 0);
                ipc_answer(&TASK->kernel_box, call);
 
                ipl = interrupts_disable();
                spinlock_lock(&TASK->lock);
                spinlock_lock(&TASK->answerbox.lock);
                if (list_empty(&TASK->answerbox.connected_phones)) {
                    /* Last phone has been disconnected */
                    TASK->kb_thread = NULL;
                    done = true;
                    klog_printf("phone list is empty");
                }
                spinlock_unlock(&TASK->answerbox.lock);
                spinlock_unlock(&TASK->lock);
                interrupts_restore(ipl);
            }
        }
    }
 
    klog_printf("kbox: done, waking up possible shutdown routine");
    waitq_wakeup(&TASK->kb_thread_shutdown_wq, WAKEUP_ALL);
    klog_printf("kbox: finished");
}
 
 
/**
 * Connect phone to a task kernel-box specified by id.
 *
 * Note that this is not completely atomic. For optimisation reasons,
 * The task might start cleaning up kbox after the phone has been connected
 * and before a kbox thread has been created. This must be taken into account
 * in the cleanup code.
 *
 * @return      Phone id on success, or negative error code.
 */
int ipc_connect_kbox(task_id_t taskid)
{
    int newphid;
    task_t *ta;
    thread_t *kb_thread;
    ipl_t ipl;
    bool had_kb_thread;
 
    newphid = phone_alloc();
    if (newphid < 0)
        return ELIMIT;
 
    ipl = interrupts_disable();
    spinlock_lock(&tasks_lock);
 
    ta = task_find_by_id(taskid);
    if (ta == NULL) {
        spinlock_unlock(&tasks_lock);
        interrupts_restore(ipl);
        return ENOENT;
    }
 
    spinlock_lock(&ta->kb_cleanup_lock);
    spinlock_unlock(&tasks_lock);
 
    /*
     * Only ta->kb_cleanup_lock left. Since we checked the value
     * of ta->kb_finished, this suffices to ensure the task's exitence.
     * (And that it didn't start kbox cleanup yet). It also ensures
     * mutual exclusion with other threads running this function.
     */
 
    if (ta->kb_finished != false) {
        spinlock_unlock(&ta->kb_cleanup_lock);
        interrupts_restore(ipl);
        return EINVAL;
    }
 
    /* Connect the newly allocated phone to the kbox */
    ipc_phone_connect(&TASK->phones[newphid], &ta->kernel_box);
 
    had_kb_thread = (ta->kb_thread != NULL);
   
    /*
     * Release all locks. This is an optimisation, that makes
     * unnecessary thread creation very unlikely.
     */
    spinlock_unlock(&ta->kb_cleanup_lock);
    interrupts_restore(ipl);
 
    /* Create a kbox thread */
 
    kb_thread = thread_create(kbox_thread_proc,
        NULL, ta, THREAD_FLAG_NOATTACH, "kbox", false);
    if (!kb_thread)
        return ENOMEM;
 
    /*
     * It might happen that someone else has attached a kbox thread.
     * in the meantime. Also, the task might have gone or shut down.
     * Let's try from the beginning.
     */
 
    ipl = interrupts_disable();
    spinlock_lock(&tasks_lock);
 
    ta = task_find_by_id(taskid);
    if (ta == NULL) {
        spinlock_unlock(&tasks_lock);
        return ENOENT;
    }
 
    spinlock_lock(&ta->kb_cleanup_lock);
    spinlock_unlock(&tasks_lock);
 
    if (ta->kb_finished != false || ta->kb_thread != NULL) {
        spinlock_unlock(&ta->kb_cleanup_lock);
        interrupts_restore(ipl);
 
        /*
         * Release the allocated thread struct. This won't
         * happen too often, only if two CPUs raced for
         * connecting to the kbox.
         */
        thread_unattached_free(kb_thread);
        return EINVAL;
    }
 
    /* Attach thread */
    ta->kb_thread = kb_thread;
    thread_attach(kb_thread, ta);
 
    thread_detach(kb_thread);
    thread_ready(kb_thread);
 
    spinlock_unlock(&ta->kb_cleanup_lock);
    interrupts_restore(ipl);
 
    return newphid;
}
 
/** @}
 */
 
Subversion Repositories HelenOS

(root)/branches/tracing/kernel/generic/src/ipc/ipc.c @ 3438 – Rev 2913 → 3014
