Subversion Repositories HelenOS

Rev

Rev 1787 | Rev 2359 | Go to most recent revision | Details | Compare with Previous | Last modification | View Log | RSS feed

Rev Author Line No. Line
1072 palkovsky 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
 
1757 jermar 29
/** @addtogroup genericipc
1702 cejka 30
 * @{
31
 */
32
/** @file
33
 */
34
 
1072 palkovsky 35
/* IPC resources management
36
 *
37
 * The goal of this source code is to properly manage IPC resources
38
 * and allow straight and clean clean-up procedure upon task termination.
39
 *
40
 * The pattern of usage of the resources is:
41
 * - allocate empty phone slot, connect | deallocate slot
42
 * - disconnect connected phone (some messages might be on the fly)
43
 * - find phone in slot and send a message using phone
44
 * - answer message to phone
1086 palkovsky 45
 * - hangup phone (the caller has hung up)
46
 * - hangup phone (the answerbox is exiting)
1072 palkovsky 47
 *
1084 palkovsky 48
 * Locking strategy
49
 *
50
 * - To use a phone, disconnect a phone etc., the phone must be
51
 *   first locked and then checked that it is connected
52
 * - To connect an allocated phone it need not be locked (assigning
53
 *   pointer is atomic on all platforms)
54
 *
55
 * - To find an empty phone slot, the TASK must be locked
56
 * - To answer a message, the answerbox must be locked
57
 * - The locking of phone and answerbox is done at the ipc_ level.
58
 *   It is perfectly correct to pass unconnected phone to these functions
59
 *   and proper reply will be generated.
60
 *
61
 * Locking order
62
 *
63
 * - first phone, then answerbox
64
 *   + Easy locking on calls
65
 *   - Very hard traversing list of phones when disconnecting because
66
 *     the phones may disconnect during traversal of list of connected phones.
67
 *     The only possibility is try_lock with restart of list traversal.
68
 *
1086 palkovsky 69
 * Destroying is less frequent, this approach is taken.
1084 palkovsky 70
 *
1090 palkovsky 71
 * Phone call
72
 *
73
 * *** Connect_me_to ***
74
 * The caller sends IPC_M_CONNECT_ME_TO to an answerbox. The server
75
 * receives 'phoneid' of the connecting phone as an ARG3. If it answers
76
 * with RETVAL=0, the phonecall is accepted, otherwise it is refused.
77
 *
78
 * *** Connect_to_me ***
79
 * The caller sends IPC_M_CONNECT_TO_ME, with special
80
 * The server receives an automatically
81
 * opened phoneid. If it accepts (RETVAL=0), it can use the phoneid
82
 * immediately.
83
 * Possible race condition can arise, when the client receives messages
84
 * from new connection before getting response for connect_to_me message.
85
 * Userspace should implement handshake protocol that would control it.
86
 *
1086 palkovsky 87
 * Phone hangup
88
 *
89
 * *** The caller hangs up (sys_ipc_hangup) ***
90
 * - The phone is disconnected (no more messages can be sent over this phone),
91
 *   all in-progress messages are correctly handled. The anwerbox receives
92
 *   IPC_M_PHONE_HUNGUP call from the phone that hung up. When all async
93
 *   calls are answered, the phone is deallocated.
1084 palkovsky 94
 *
1088 palkovsky 95
 * *** The answerbox hangs up (ipc_answer(EHANGUP))
96
 * - The phone is disconnected. EHANGUP response code is sent
1698 jermar 97
 *   to the calling task. All new calls through this phone
1088 palkovsky 98
 *   get a EHUNGUP error code, the task is expected to
1888 jermar 99
 *   send an sys_ipc_hangup after cleaning up its internal structures.
1086 palkovsky 100
 *
1088 palkovsky 101
 * Call forwarding
102
 *
103
 * The call can be forwarded, so that the answer to call is passed directly
104
 * to the original sender. However, this poses special problems regarding
105
 * routing of hangup messages.
106
 *
107
 * sys_ipc_hangup -> IPC_M_PHONE_HUNGUP
108
 * - this message CANNOT be forwarded
109
 *
110
 * EHANGUP during forward
111
 * - The *forwarding* phone will be closed, EFORWARD is sent to receiver.
112
 *
113
 * EHANGUP, ENOENT during forward
114
 * - EFORWARD is sent to the receiver, ipc_forward returns error code EFORWARD
115
 *
1084 palkovsky 116
 * Cleanup strategy
1072 palkovsky 117
 *
1088 palkovsky 118
 * 1) Disconnect all our phones ('ipc_phone_hangup').
1086 palkovsky 119
 *
120
 * 2) Disconnect all phones connected to answerbox.
1084 palkovsky 121
 *
1086 palkovsky 122
 * 3) Answer all messages in 'calls' and 'dispatched_calls' queues with
1088 palkovsky 123
 *    appropriate error code (EHANGUP, EFORWARD).
1084 palkovsky 124
 *
1090 palkovsky 125
 * 4) Wait for all async answers to arrive and dispose of them.
1084 palkovsky 126
 *
1072 palkovsky 127
 */
128
 
129
#include <synch/spinlock.h>
130
#include <ipc/ipc.h>
131
#include <arch.h>
132
#include <proc/task.h>
133
#include <ipc/ipcrsc.h>
134
#include <debug.h>
135
 
136
/** Find call_t * in call table according to callid
137
 *
1141 palkovsky 138
 * TODO: Some speedup (hash table?)
1072 palkovsky 139
 * @return NULL on not found, otherwise pointer to call structure
140
 */
1780 jermar 141
call_t * get_call(unative_t callid)
1072 palkovsky 142
{
1141 palkovsky 143
    link_t *lst;
144
    call_t *call, *result = NULL;
145
 
146
    spinlock_lock(&TASK->answerbox.lock);
147
    for (lst = TASK->answerbox.dispatched_calls.next;
148
         lst != &TASK->answerbox.dispatched_calls; lst = lst->next) {
1573 palkovsky 149
        call = list_get_instance(lst, call_t, link);
1780 jermar 150
        if ((unative_t)call == callid) {
1141 palkovsky 151
            result = call;
152
            break;
153
        }
154
    }
155
    spinlock_unlock(&TASK->answerbox.lock);
156
    return result;
1072 palkovsky 157
}
158
 
159
/** Allocate new phone slot in current TASK structure */
160
int phone_alloc(void)
161
{
162
    int i;
163
 
164
    spinlock_lock(&TASK->lock);
165
 
166
    for (i=0; i < IPC_MAX_PHONES; i++) {
1568 palkovsky 167
        if (TASK->phones[i].state == IPC_PHONE_HUNGUP && \
168
            atomic_get(&TASK->phones[i].active_calls) == 0)
169
            TASK->phones[i].state = IPC_PHONE_FREE;
170
 
171
        if (TASK->phones[i].state == IPC_PHONE_FREE) {
172
            TASK->phones[i].state = IPC_PHONE_CONNECTING;
1072 palkovsky 173
            break;
174
        }
175
    }
176
    spinlock_unlock(&TASK->lock);
177
 
178
    if (i >= IPC_MAX_PHONES)
179
        return -1;
180
    return i;
181
}
182
 
1090 palkovsky 183
static void phone_deallocp(phone_t *phone)
184
{
1568 palkovsky 185
    ASSERT(phone->state == IPC_PHONE_CONNECTING);
1090 palkovsky 186
 
187
    /* atomic operation */
1568 palkovsky 188
    phone->state = IPC_PHONE_FREE;
1090 palkovsky 189
}
190
 
191
/** Free slot from a disconnected phone
1086 palkovsky 192
 *
193
 * All already sent messages will be correctly processed
194
 */
1072 palkovsky 195
void phone_dealloc(int phoneid)
196
{
1090 palkovsky 197
    phone_deallocp(&TASK->phones[phoneid]);
1072 palkovsky 198
}
199
 
1084 palkovsky 200
/** Connect phone to a given answerbox
201
 *
202
 * @param phoneid The slot that will be connected
203
 *
204
 * The procedure _enforces_ that the user first marks the phone
205
 * busy (e.g. via phone_alloc) and then connects the phone, otherwise
206
 * race condition may appear.
207
 */
1072 palkovsky 208
void phone_connect(int phoneid, answerbox_t *box)
209
{
210
    phone_t *phone = &TASK->phones[phoneid];
211
 
1568 palkovsky 212
    ASSERT(phone->state == IPC_PHONE_CONNECTING);
1072 palkovsky 213
    ipc_phone_connect(phone, box);
214
}
1702 cejka 215
 
1757 jermar 216
/** @}
1702 cejka 217
 */