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| 1072 | palkovsky | 1 | /* |
| 2 | * Copyright (C) 2006 Ondrej Palkovsky |
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| 3 | * All rights reserved. |
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| 4 | * |
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| 5 | * Redistribution and use in source and binary forms, with or without |
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| 6 | * modification, are permitted provided that the following conditions |
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| 7 | * are met: |
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| 8 | * |
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| 9 | * - Redistributions of source code must retain the above copyright |
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| 10 | * notice, this list of conditions and the following disclaimer. |
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| 11 | * - Redistributions in binary form must reproduce the above copyright |
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| 12 | * notice, this list of conditions and the following disclaimer in the |
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| 13 | * documentation and/or other materials provided with the distribution. |
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| 14 | * - The name of the author may not be used to endorse or promote products |
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| 15 | * derived from this software without specific prior written permission. |
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| 16 | * |
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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| 27 | */ |
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| 28 | |||
| 29 | /* IPC resources management |
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| 30 | * |
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| 31 | * The goal of this source code is to properly manage IPC resources |
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| 32 | * and allow straight and clean clean-up procedure upon task termination. |
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| 33 | * |
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| 34 | * The pattern of usage of the resources is: |
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| 35 | * - allocate empty phone slot, connect | deallocate slot |
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| 36 | * - disconnect connected phone (some messages might be on the fly) |
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| 37 | * - find phone in slot and send a message using phone |
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| 38 | * - answer message to phone |
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| 1086 | palkovsky | 39 | * - hangup phone (the caller has hung up) |
| 40 | * - hangup phone (the answerbox is exiting) |
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| 1072 | palkovsky | 41 | * |
| 1084 | palkovsky | 42 | * Locking strategy |
| 43 | * |
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| 44 | * - To use a phone, disconnect a phone etc., the phone must be |
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| 45 | * first locked and then checked that it is connected |
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| 46 | * - To connect an allocated phone it need not be locked (assigning |
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| 47 | * pointer is atomic on all platforms) |
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| 48 | * |
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| 49 | * - To find an empty phone slot, the TASK must be locked |
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| 50 | * - To answer a message, the answerbox must be locked |
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| 51 | * - The locking of phone and answerbox is done at the ipc_ level. |
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| 52 | * It is perfectly correct to pass unconnected phone to these functions |
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| 53 | * and proper reply will be generated. |
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| 54 | * |
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| 55 | * Locking order |
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| 56 | * |
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| 57 | * - first phone, then answerbox |
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| 58 | * + Easy locking on calls |
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| 59 | * - Very hard traversing list of phones when disconnecting because |
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| 60 | * the phones may disconnect during traversal of list of connected phones. |
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| 61 | * The only possibility is try_lock with restart of list traversal. |
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| 62 | * |
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| 1086 | palkovsky | 63 | * Destroying is less frequent, this approach is taken. |
| 1084 | palkovsky | 64 | * |
| 1090 | palkovsky | 65 | * Phone call |
| 66 | * |
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| 67 | * *** Connect_me_to *** |
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| 68 | * The caller sends IPC_M_CONNECT_ME_TO to an answerbox. The server |
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| 69 | * receives 'phoneid' of the connecting phone as an ARG3. If it answers |
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| 70 | * with RETVAL=0, the phonecall is accepted, otherwise it is refused. |
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| 71 | * |
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| 72 | * *** Connect_to_me *** |
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| 73 | * The caller sends IPC_M_CONNECT_TO_ME, with special |
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| 74 | * The server receives an automatically |
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| 75 | * opened phoneid. If it accepts (RETVAL=0), it can use the phoneid |
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| 76 | * immediately. |
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| 77 | * Possible race condition can arise, when the client receives messages |
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| 78 | * from new connection before getting response for connect_to_me message. |
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| 79 | * Userspace should implement handshake protocol that would control it. |
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| 80 | * |
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| 1086 | palkovsky | 81 | * Phone hangup |
| 82 | * |
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| 83 | * *** The caller hangs up (sys_ipc_hangup) *** |
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| 84 | * - The phone is disconnected (no more messages can be sent over this phone), |
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| 85 | * all in-progress messages are correctly handled. The anwerbox receives |
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| 86 | * IPC_M_PHONE_HUNGUP call from the phone that hung up. When all async |
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| 87 | * calls are answered, the phone is deallocated. |
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| 1084 | palkovsky | 88 | * |
| 1088 | palkovsky | 89 | * *** The answerbox hangs up (ipc_answer(EHANGUP)) |
| 90 | * - The phone is disconnected. EHANGUP response code is sent |
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| 91 | * to the calling process. All new calls through this phone |
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| 92 | * get a EHUNGUP error code, the task is expected to |
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| 1086 | palkovsky | 93 | * send an sys_ipc_hangup after cleaning up it's internal structures. |
| 94 | * |
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| 1088 | palkovsky | 95 | * Call forwarding |
| 96 | * |
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| 97 | * The call can be forwarded, so that the answer to call is passed directly |
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| 98 | * to the original sender. However, this poses special problems regarding |
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| 99 | * routing of hangup messages. |
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| 100 | * |
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| 101 | * sys_ipc_hangup -> IPC_M_PHONE_HUNGUP |
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| 102 | * - this message CANNOT be forwarded |
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| 103 | * |
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| 104 | * EHANGUP during forward |
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| 105 | * - The *forwarding* phone will be closed, EFORWARD is sent to receiver. |
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| 106 | * |
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| 107 | * EHANGUP, ENOENT during forward |
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| 108 | * - EFORWARD is sent to the receiver, ipc_forward returns error code EFORWARD |
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| 109 | * |
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| 1084 | palkovsky | 110 | * Cleanup strategy |
| 1072 | palkovsky | 111 | * |
| 1088 | palkovsky | 112 | * 1) Disconnect all our phones ('ipc_phone_hangup'). |
| 1086 | palkovsky | 113 | * |
| 114 | * 2) Disconnect all phones connected to answerbox. |
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| 1084 | palkovsky | 115 | * |
| 1086 | palkovsky | 116 | * 3) Answer all messages in 'calls' and 'dispatched_calls' queues with |
| 1088 | palkovsky | 117 | * appropriate error code (EHANGUP, EFORWARD). |
| 1084 | palkovsky | 118 | * |
| 1090 | palkovsky | 119 | * 4) Wait for all async answers to arrive and dispose of them. |
| 1084 | palkovsky | 120 | * |
| 1072 | palkovsky | 121 | */ |
| 122 | |||
| 123 | #include <synch/spinlock.h> |
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| 124 | #include <ipc/ipc.h> |
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| 125 | #include <arch.h> |
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| 126 | #include <proc/task.h> |
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| 127 | #include <ipc/ipcrsc.h> |
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| 128 | #include <debug.h> |
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| 129 | |||
| 130 | /** Find call_t * in call table according to callid |
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| 131 | * |
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| 132 | * @return NULL on not found, otherwise pointer to call structure |
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| 133 | */ |
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| 134 | call_t * get_call(__native callid) |
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| 135 | { |
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| 136 | /* TODO: Traverse list of dispatched calls and find one */ |
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| 137 | /* TODO: locking of call, ripping it from dispatched calls etc. */ |
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| 138 | return (call_t *) callid; |
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| 139 | } |
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| 140 | |||
| 141 | /** Allocate new phone slot in current TASK structure */ |
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| 142 | int phone_alloc(void) |
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| 143 | { |
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| 144 | int i; |
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| 145 | |||
| 146 | spinlock_lock(&TASK->lock); |
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| 147 | |||
| 148 | for (i=0; i < IPC_MAX_PHONES; i++) { |
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| 1088 | palkovsky | 149 | if (TASK->phones[i].busy==IPC_BUSY_FREE && !atomic_get(&TASK->phones[i].active_calls)) { |
| 150 | TASK->phones[i].busy = IPC_BUSY_CONNECTING; |
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| 1072 | palkovsky | 151 | break; |
| 152 | } |
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| 153 | } |
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| 154 | spinlock_unlock(&TASK->lock); |
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| 155 | |||
| 156 | if (i >= IPC_MAX_PHONES) |
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| 157 | return -1; |
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| 158 | return i; |
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| 159 | } |
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| 160 | |||
| 1090 | palkovsky | 161 | static void phone_deallocp(phone_t *phone) |
| 162 | { |
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| 163 | ASSERT(phone->busy == IPC_BUSY_CONNECTING); |
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| 164 | ASSERT(! phone->callee); |
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| 165 | |||
| 166 | /* atomic operation */ |
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| 167 | phone->busy = IPC_BUSY_FREE; |
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| 168 | } |
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| 169 | |||
| 170 | /** Free slot from a disconnected phone |
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| 1086 | palkovsky | 171 | * |
| 172 | * All already sent messages will be correctly processed |
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| 173 | */ |
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| 1072 | palkovsky | 174 | void phone_dealloc(int phoneid) |
| 175 | { |
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| 1090 | palkovsky | 176 | phone_deallocp(&TASK->phones[phoneid]); |
| 1072 | palkovsky | 177 | } |
| 178 | |||
| 1084 | palkovsky | 179 | /** Connect phone to a given answerbox |
| 180 | * |
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| 181 | * @param phoneid The slot that will be connected |
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| 182 | * |
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| 183 | * The procedure _enforces_ that the user first marks the phone |
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| 184 | * busy (e.g. via phone_alloc) and then connects the phone, otherwise |
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| 185 | * race condition may appear. |
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| 186 | */ |
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| 1072 | palkovsky | 187 | void phone_connect(int phoneid, answerbox_t *box) |
| 188 | { |
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| 189 | phone_t *phone = &TASK->phones[phoneid]; |
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| 190 | |||
| 1088 | palkovsky | 191 | ASSERT(phone->busy == IPC_BUSY_CONNECTING); |
| 1072 | palkovsky | 192 | ipc_phone_connect(phone, box); |
| 193 | } |