source: mainline/kernel/generic/src/ipc/kbox.c@ a000878c

/*
 * Copyright (c) 2008 Jiri Svoboda
 * 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
 */

#include <synch/synch.h>
#include <synch/spinlock.h>
#include <synch/mutex.h>
#include <ipc/ipc.h>
#include <ipc/ipcrsc.h>
#include <arch.h>
#include <errno.h>
#include <debug.h>
#include <udebug/udebug_ipc.h>
#include <ipc/kbox.h>
#include <print.h>

void ipc_kbox_cleanup(void)
{
        ipl_t ipl;
        bool have_kb_thread;

        /* 
         * Only hold kb.cleanup_lock while setting kb.finished -
         * this is enough.
         */
        mutex_lock(&TASK->kb.cleanup_lock);
        TASK->kb.finished = true;
        mutex_unlock(&TASK->kb.cleanup_lock);

        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->kb.box, have_kb_thread);

        /* 
         * If the task was being debugged, clean up debugging session.
         * This is necessarry as slamming the phones won't force
         * kbox thread to clean it up since sender != debugger.
         */
        ipl = interrupts_disable();
        spinlock_lock(&TASK->lock);
        udebug_task_cleanup(TASK);
        spinlock_unlock(&TASK->lock);
        interrupts_restore(ipl);
        
        if (have_kb_thread) {
                LOG("Join kb.thread.");
                thread_join(TASK->kb.thread);
                thread_detach(TASK->kb.thread);
                LOG("...join done.");
                TASK->kb.thread = NULL;
        }

        /* Answer all messages in 'calls' and 'dispatched_calls' queues. */
        spinlock_lock(&TASK->kb.box.lock);
        ipc_cleanup_call_list(&TASK->kb.box.dispatched_calls);
        ipc_cleanup_call_list(&TASK->kb.box.calls);
        spinlock_unlock(&TASK->kb.box.lock);
}

/** Handle hangup message in kbox.
 *
 * @param call  The IPC_M_PHONE_HUNGUP call structure.
 * @param last  Output, the function stores @c true here if
 *              this was the last phone, @c false otherwise.
 **/
static void kbox_proc_phone_hungup(call_t *call, bool *last)
{
        ipl_t ipl;

        /* Was it our debugger, who hung up? */
        if (call->sender == TASK->udebug.debugger) {
                /* Terminate debugging session (if any). */
                LOG("Terminate debugging session.");
                ipl = interrupts_disable();
                spinlock_lock(&TASK->lock);
                udebug_task_cleanup(TASK);
                spinlock_unlock(&TASK->lock);
                interrupts_restore(ipl);
        } else {
                LOG("Was not debugger.");
        }

        LOG("Continue with hangup message.");
        IPC_SET_RETVAL(call->data, 0);
        ipc_answer(&TASK->kb.box, call);

        ipl = interrupts_disable();
        spinlock_lock(&TASK->lock);
        spinlock_lock(&TASK->kb.box.lock);
        if (list_empty(&TASK->kb.box.connected_phones)) {
                /*
                 * Last phone has been disconnected. Detach this thread so it
                 * gets freed and signal to the caller.
                 */

                /* Only detach kbox thread unless already terminating. */
                mutex_lock(&TASK->kb.cleanup_lock);
                if (TASK->kb.finished == false) {
                        /* Detach kbox thread so it gets freed from memory. */
                        thread_detach(TASK->kb.thread);
                        TASK->kb.thread = NULL;
                }
                mutex_unlock(&TASK->kb.cleanup_lock);

                LOG("Phone list is empty.");
                *last = true;
        } else {
                *last = false;
        }

        spinlock_unlock(&TASK->kb.box.lock);
        spinlock_unlock(&TASK->lock);
        interrupts_restore(ipl);
}

/** Implementing function for the kbox thread.
 *
 * This function listens for debug requests. It terminates
 * when all phones are disconnected from the kbox.
 *
 * @param arg   Ignored.
 */
static void kbox_thread_proc(void *arg)
{
        call_t *call;
        bool done;

        (void)arg;
        LOG("Starting.");
        done = false;

        while (!done) {
                call = ipc_wait_for_call(&TASK->kb.box, SYNCH_NO_TIMEOUT,
                        SYNCH_FLAGS_NONE);

                if (call == NULL)
                        continue;       /* Try again. */

                switch (IPC_GET_METHOD(call->data)) {

                case IPC_M_DEBUG_ALL:
                        /* Handle debug call. */
                        udebug_call_receive(call);
                        break;

                case IPC_M_PHONE_HUNGUP:
                        /*
                         * Process the hangup call. If this was the last
                         * phone, done will be set to true and the
                         * while loop will terminate.
                         */
                        kbox_proc_phone_hungup(call, &done);
                        break;

                default:
                        /* Ignore */
                        break;
                }
        }

        LOG("Exiting.");
}


/**
 * 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;

        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;
        }

        atomic_inc(&ta->refcount);

        spinlock_unlock(&tasks_lock);
        interrupts_restore(ipl);

        mutex_lock(&ta->kb.cleanup_lock);

        if (atomic_predec(&ta->refcount) == 0) {
                mutex_unlock(&ta->kb.cleanup_lock);
                task_destroy(ta);
                return ENOENT;
        }

        if (ta->kb.finished != false) {
                mutex_unlock(&ta->kb.cleanup_lock);
                return EINVAL;
        }

        newphid = phone_alloc(TASK);
        if (newphid < 0) {
                mutex_unlock(&ta->kb.cleanup_lock);
                return ELIMIT;
        }

        /* Connect the newly allocated phone to the kbox */
        ipc_phone_connect(&TASK->phones[newphid], &ta->kb.box);

        if (ta->kb.thread != NULL) {
                mutex_unlock(&ta->kb.cleanup_lock);
                return newphid;
        }

        /* Create a kbox thread */
        kb_thread = thread_create(kbox_thread_proc, NULL, ta, 0,
            "kbox", false);
        if (!kb_thread) {
                mutex_unlock(&ta->kb.cleanup_lock);
                return ENOMEM;
        }

        ta->kb.thread = kb_thread;
        thread_ready(kb_thread);

        mutex_unlock(&ta->kb.cleanup_lock);

        return newphid;
}

/** @}
 */