source: mainline/kernel/generic/src/ipc/ops/connclone.c@ e7c4115d

/*
 * Copyright (c) 2012 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 genericipc
 * @{
 */
/** @file
 */

#include <ipc/sysipc_ops.h>
#include <ipc/ipc.h>
#include <ipc/ipcrsc.h>
#include <synch/mutex.h>
#include <abi/errno.h>
#include <arch.h>

static void phones_lock(phone_t *p1, phone_t *p2)
{
        if (p1 < p2) {
                mutex_lock(&p1->lock);
                mutex_lock(&p2->lock);
        } else if (p1 > p2) {
                mutex_lock(&p2->lock);
                mutex_lock(&p1->lock);
        } else
                mutex_lock(&p1->lock);
}

static void phones_unlock(phone_t *p1, phone_t *p2)
{
        mutex_unlock(&p1->lock);
        if (p1 != p2)
                mutex_unlock(&p2->lock);
}

static int request_preprocess(call_t *call, phone_t *phone)
{
        phone_t *cloned_phone = phone_get_current(IPC_GET_ARG1(call->data));
        if (!cloned_phone)
                return ENOENT;
        
        phones_lock(cloned_phone, phone);
        
        if ((cloned_phone->state != IPC_PHONE_CONNECTED) ||
            phone->state != IPC_PHONE_CONNECTED) {
                phones_unlock(cloned_phone, phone);
                return EINVAL;
        }
        
        /*
         * We can be pretty sure now that both tasks exist and we are
         * connected to them. As we continue to hold the phone locks,
         * we are effectively preventing them from finishing their
         * potential cleanup.
         *
         */
        int cap = phone_alloc(phone->callee->task);
        if (cap < 0) {
                phones_unlock(cloned_phone, phone);
                return ELIMIT;
        }
        
        (void) ipc_phone_connect(phone_get(phone->callee->task, cap),
            cloned_phone->callee);
        phones_unlock(cloned_phone, phone);
        
        /* Set the new phone for the callee. */
        IPC_SET_ARG1(call->data, cap);

        return EOK;
}

static int answer_cleanup(call_t *answer, ipc_data_t *olddata)
{
        int cap = (int) IPC_GET_ARG1(*olddata);
        phone_t *phone = phone_get_current(cap);

        /*
         * In this case, the connection was established at the request
         * time and therefore we need to slam the phone.  We don't
         * merely hangup as that would result in sending IPC_M_HUNGUP
         * to the third party on the other side of the cloned phone.
         */
        mutex_lock(&phone->lock);
        if (phone->state == IPC_PHONE_CONNECTED) {
                irq_spinlock_lock(&phone->callee->lock, true);
                list_remove(&phone->link);
                phone->state = IPC_PHONE_SLAMMED;
                irq_spinlock_unlock(&phone->callee->lock, true);
        }
        mutex_unlock(&phone->lock);

        return EOK;
}

static int answer_preprocess(call_t *answer, ipc_data_t *olddata)
{
        if (IPC_GET_RETVAL(answer->data) != EOK) {
                /*
                 * The recipient of the cloned phone rejected the offer.
                 */
                answer_cleanup(answer, olddata);
        }

        return EOK;
}

sysipc_ops_t ipc_m_connection_clone_ops = {
        .request_preprocess = request_preprocess,
        .request_forget = null_request_forget,
        .request_process = null_request_process,
        .answer_cleanup = answer_cleanup,
        .answer_preprocess = answer_preprocess,
        .answer_process = null_answer_process,
};

/** @}
 */