Subversion Repositories HelenOS-historic

Rev

Rev 1088 | Rev 1141 | 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
 
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
1086 palkovsky 39
 * - hangup phone (the caller has hung up)
40
 * - hangup phone (the answerbox is exiting)
1072 palkovsky 41
 *
1084 palkovsky 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
 *
1086 palkovsky 63
 * Destroying is less frequent, this approach is taken.
1084 palkovsky 64
 *
1090 palkovsky 65
 * Phone call
66
 *
67
 * *** Connect_me_to ***
68
 * The caller sends IPC_M_CONNECT_ME_TO to an answerbox. The server
69
 * receives 'phoneid' of the connecting phone as an ARG3. If it answers
70
 * with RETVAL=0, the phonecall is accepted, otherwise it is refused.
71
 *
72
 * *** Connect_to_me ***
73
 * The caller sends IPC_M_CONNECT_TO_ME, with special
74
 * The server receives an automatically
75
 * opened phoneid. If it accepts (RETVAL=0), it can use the phoneid
76
 * immediately.
77
 * Possible race condition can arise, when the client receives messages
78
 * from new connection before getting response for connect_to_me message.
79
 * Userspace should implement handshake protocol that would control it.
80
 *
1086 palkovsky 81
 * Phone hangup
82
 *
83
 * *** The caller hangs up (sys_ipc_hangup) ***
84
 * - The phone is disconnected (no more messages can be sent over this phone),
85
 *   all in-progress messages are correctly handled. The anwerbox receives
86
 *   IPC_M_PHONE_HUNGUP call from the phone that hung up. When all async
87
 *   calls are answered, the phone is deallocated.
1084 palkovsky 88
 *
1088 palkovsky 89
 * *** The answerbox hangs up (ipc_answer(EHANGUP))
90
 * - The phone is disconnected. EHANGUP response code is sent
91
 *   to the calling process. All new calls through this phone
92
 *   get a EHUNGUP error code, the task is expected to
1086 palkovsky 93
 *   send an sys_ipc_hangup after cleaning up it's internal structures.
94
 *
1088 palkovsky 95
 * Call forwarding
96
 *
97
 * The call can be forwarded, so that the answer to call is passed directly
98
 * to the original sender. However, this poses special problems regarding
99
 * routing of hangup messages.
100
 *
101
 * sys_ipc_hangup -> IPC_M_PHONE_HUNGUP
102
 * - this message CANNOT be forwarded
103
 *
104
 * EHANGUP during forward
105
 * - The *forwarding* phone will be closed, EFORWARD is sent to receiver.
106
 *
107
 * EHANGUP, ENOENT during forward
108
 * - EFORWARD is sent to the receiver, ipc_forward returns error code EFORWARD
109
 *
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.
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>
124
#include <ipc/ipc.h>
125
#include <arch.h>
126
#include <proc/task.h>
127
#include <ipc/ipcrsc.h>
128
#include <debug.h>
129
 
130
/** Find call_t * in call table according to callid
131
 *
132
 * @return NULL on not found, otherwise pointer to call structure
133
 */
134
call_t * get_call(__native callid)
135
{
136
    /* TODO: Traverse list of dispatched calls and find one */
137
    /* TODO: locking of call, ripping it from dispatched calls etc.  */
138
    return (call_t *) callid;
139
}
140
 
141
/** Allocate new phone slot in current TASK structure */
142
int phone_alloc(void)
143
{
144
    int i;
145
 
146
    spinlock_lock(&TASK->lock);
147
 
148
    for (i=0; i < IPC_MAX_PHONES; i++) {
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;
1072 palkovsky 151
            break;
152
        }
153
    }
154
    spinlock_unlock(&TASK->lock);
155
 
156
    if (i >= IPC_MAX_PHONES)
157
        return -1;
158
    return i;
159
}
160
 
1090 palkovsky 161
static void phone_deallocp(phone_t *phone)
162
{
163
    ASSERT(phone->busy == IPC_BUSY_CONNECTING);
164
    ASSERT(! phone->callee);
165
 
166
    /* atomic operation */
167
    phone->busy = IPC_BUSY_FREE;
168
}
169
 
170
/** Free slot from a disconnected phone
1086 palkovsky 171
 *
172
 * All already sent messages will be correctly processed
173
 */
1072 palkovsky 174
void phone_dealloc(int phoneid)
175
{
1090 palkovsky 176
    phone_deallocp(&TASK->phones[phoneid]);
1072 palkovsky 177
}
178
 
1084 palkovsky 179
/** Connect phone to a given answerbox
180
 *
181
 * @param phoneid The slot that will be connected
182
 *
183
 * The procedure _enforces_ that the user first marks the phone
184
 * busy (e.g. via phone_alloc) and then connects the phone, otherwise
185
 * race condition may appear.
186
 */
1072 palkovsky 187
void phone_connect(int phoneid, answerbox_t *box)
188
{
189
    phone_t *phone = &TASK->phones[phoneid];
190
 
1088 palkovsky 191
    ASSERT(phone->busy == IPC_BUSY_CONNECTING);
1072 palkovsky 192
    ipc_phone_connect(phone, box);
193
}