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  1. /*
  2.  * Copyright (C) 2006 Ondrej Palkovsky
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /* IPC resources management
  30.  *
  31.  * The goal of this source code is to properly manage IPC resources
  32.  * and allow straight and clean clean-up procedure upon task termination.
  33.  *
  34.  * The pattern of usage of the resources is:
  35.  * - allocate empty phone slot, connect | deallocate slot
  36.  * - disconnect connected phone (some messages might be on the fly)
  37.  * - find phone in slot and send a message using phone
  38.  * - answer message to phone
  39.  * - hangup phone (the caller has hung up)
  40.  * - hangup phone (the answerbox is exiting)
  41.  *
  42.  * Locking strategy
  43.  *
  44.  * - To use a phone, disconnect a phone etc., the phone must be
  45.  *   first locked and then checked that it is connected
  46.  * - To connect an allocated phone it need not be locked (assigning
  47.  *   pointer is atomic on all platforms)
  48.  *
  49.  * - To find an empty phone slot, the TASK must be locked
  50.  * - To answer a message, the answerbox must be locked
  51.  * - The locking of phone and answerbox is done at the ipc_ level.
  52.  *   It is perfectly correct to pass unconnected phone to these functions
  53.  *   and proper reply will be generated.
  54.  *
  55.  * Locking order
  56.  *
  57.  * - first phone, then answerbox
  58.  *   + Easy locking on calls
  59.  *   - Very hard traversing list of phones when disconnecting because
  60.  *     the phones may disconnect during traversal of list of connected phones.
  61.  *     The only possibility is try_lock with restart of list traversal.
  62.  *
  63.  * Destroying is less frequent, this approach is taken.
  64.  *
  65.  * Phone hangup
  66.  *
  67.  * *** The caller hangs up (sys_ipc_hangup) ***
  68.  * - The phone is disconnected (no more messages can be sent over this phone),
  69.  *   all in-progress messages are correctly handled. The anwerbox receives
  70.  *   IPC_M_PHONE_HUNGUP call from the phone that hung up. When all async
  71.  *   calls are answered, the phone is deallocated.
  72.  *
  73.  * *** The answerbox hangs up (ipc_answer(ESLAM))
  74.  * - The phone is disconnected. IPC_M_ANSWERBOX_HUNGUP notification
  75.  *   is sent to source task, the calling process is expected to
  76.  *   send an sys_ipc_hangup after cleaning up it's internal structures.
  77.  *
  78.  * Cleanup strategy
  79.  *
  80.  * 1) Disconnect all our phones ('sys_ipc_hangup')
  81.  *
  82.  * 2) Disconnect all phones connected to answerbox.
  83.  *    * Send message 'PHONE_DISCONNECTED' to the target application
  84.  * - Once all phones are disconnected, no further calls can arrive
  85.  *
  86.  * 3) Answer all messages in 'calls' and 'dispatched_calls' queues with
  87.  *    appropriate error code.
  88.  *
  89.  * 4) Wait for all async answers to arrive
  90.  *
  91.  */
  92.  
  93. #include <synch/spinlock.h>
  94. #include <ipc/ipc.h>
  95. #include <arch.h>
  96. #include <proc/task.h>
  97. #include <ipc/ipcrsc.h>
  98. #include <debug.h>
  99.  
  100. /** Find call_t * in call table according to callid
  101.  *
  102.  * @return NULL on not found, otherwise pointer to call structure
  103.  */
  104. call_t * get_call(__native callid)
  105. {
  106.     /* TODO: Traverse list of dispatched calls and find one */
  107.     /* TODO: locking of call, ripping it from dispatched calls etc.  */
  108.     return (call_t *) callid;
  109. }
  110.  
  111. /** Allocate new phone slot in current TASK structure */
  112. int phone_alloc(void)
  113. {
  114.     int i;
  115.  
  116.     spinlock_lock(&TASK->lock);
  117.    
  118.     for (i=0; i < IPC_MAX_PHONES; i++) {
  119.         if (!TASK->phones[i].busy && !atomic_get(&TASK->phones[i].active_calls)) {
  120.             TASK->phones[i].busy = 1;
  121.             break;
  122.         }
  123.     }
  124.     spinlock_unlock(&TASK->lock);
  125.  
  126.     if (i >= IPC_MAX_PHONES)
  127.         return -1;
  128.     return i;
  129. }
  130.  
  131. /** Disconnect phone a free the slot
  132.  *
  133.  * All already sent messages will be correctly processed
  134.  */
  135. void phone_dealloc(int phoneid)
  136. {
  137.     spinlock_lock(&TASK->lock);
  138.  
  139.     ASSERT(TASK->phones[phoneid].busy);
  140.     ASSERT(! TASK->phones[phoneid].callee);
  141.  
  142.     TASK->phones[phoneid].busy = 0;
  143.     spinlock_unlock(&TASK->lock);
  144. }
  145.  
  146. /** Connect phone to a given answerbox
  147.  *
  148.  * @param phoneid The slot that will be connected
  149.  *
  150.  * The procedure _enforces_ that the user first marks the phone
  151.  * busy (e.g. via phone_alloc) and then connects the phone, otherwise
  152.  * race condition may appear.
  153.  */
  154. void phone_connect(int phoneid, answerbox_t *box)
  155. {
  156.     phone_t *phone = &TASK->phones[phoneid];
  157.    
  158.     ASSERT(phone->busy);
  159.     ipc_phone_connect(phone, box);
  160. }
  161.