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1113 palkovsky 1
/*
2071 jermar 2
 * Copyright (c) 2006 Ondrej Palkovsky
2481 jermar 3
 * Copyright (c) 2007 Jakub Jermar
1113 palkovsky 4
 * All rights reserved.
5
 *
6
 * Redistribution and use in source and binary forms, with or without
7
 * modification, are permitted provided that the following conditions
8
 * are met:
9
 *
10
 * - Redistributions of source code must retain the above copyright
11
 *   notice, this list of conditions and the following disclaimer.
12
 * - Redistributions in binary form must reproduce the above copyright
13
 *   notice, this list of conditions and the following disclaimer in the
14
 *   documentation and/or other materials provided with the distribution.
15
 * - The name of the author may not be used to endorse or promote products
16
 *   derived from this software without specific prior written permission.
17
 *
18
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28
 */
29
 
1719 decky 30
/** @addtogroup libc
1653 cejka 31
 * @{
32
 */
33
/** @file
34
 */
35
 
1113 palkovsky 36
#include <libadt/list.h>
2482 jermar 37
#include <fibril.h>
2586 jermar 38
#include <thread.h>
39
#include <tls.h>
1113 palkovsky 40
#include <malloc.h>
41
#include <unistd.h>
42
#include <stdio.h>
1781 jermar 43
#include <libarch/faddr.h>
1392 palkovsky 44
#include <futex.h>
45
#include <assert.h>
1407 palkovsky 46
#include <async.h>
1113 palkovsky 47
 
2482 jermar 48
#ifndef FIBRIL_INITIAL_STACK_PAGES_NO
49
#define FIBRIL_INITIAL_STACK_PAGES_NO   1
1155 vana 50
#endif
51
 
2483 jermar 52
/** This futex serializes access to ready_list, serialized_list and manage_list.
53
 */
54
static atomic_t fibril_futex = FUTEX_INITIALIZER;
55
 
1113 palkovsky 56
static LIST_INITIALIZE(ready_list);
1610 palkovsky 57
static LIST_INITIALIZE(serialized_list);
1392 palkovsky 58
static LIST_INITIALIZE(manager_list);
1113 palkovsky 59
 
2482 jermar 60
static void fibril_main(void);
1125 jermar 61
 
2483 jermar 62
/** Number of fibrils that are in async_serialized mode */
63
static int serialized_fibrils;  /* Protected by async_futex */
1610 palkovsky 64
/** Thread-local count of serialization. If >0, we must not preempt */
1614 palkovsky 65
static __thread int serialization_count;
2482 jermar 66
/** Counter for fibrils residing in async_manager */
67
static int fibrils_in_manager;
1392 palkovsky 68
 
2482 jermar 69
/** Setup fibril information into TCB structure */
70
fibril_t *fibril_setup(void)
1129 palkovsky 71
{
2482 jermar 72
    fibril_t *f;
1392 palkovsky 73
    tcb_t *tcb;
1129 palkovsky 74
 
1392 palkovsky 75
    tcb = __make_tls();
76
    if (!tcb)
77
        return NULL;
78
 
2568 jermar 79
    f = malloc(sizeof(fibril_t));
2482 jermar 80
    if (!f) {
1392 palkovsky 81
        __free_tls(tcb);
1129 palkovsky 82
        return NULL;
83
    }
84
 
2482 jermar 85
    tcb->fibril_data = f;
86
    f->tcb = tcb;
1129 palkovsky 87
 
2568 jermar 88
    f->func = NULL;
89
    f->arg = NULL;
90
    f->stack = NULL;
91
    f->clean_after_me = NULL;
92
    f->retval = 0;
93
    f->flags = 0;
94
 
2482 jermar 95
    return f;
1129 palkovsky 96
}
97
 
2482 jermar 98
void fibril_teardown(fibril_t *f)
1129 palkovsky 99
{
2482 jermar 100
    __free_tls(f->tcb);
101
    free(f);
1129 palkovsky 102
}
103
 
2482 jermar 104
/** Function that spans the whole life-cycle of a fibril.
2481 jermar 105
 *
2483 jermar 106
 * Each fibril begins execution in this function. Then the function implementing
107
 * the fibril logic is called.  After its return, the return value is saved.
108
 * The fibril then switches to another fibril, which cleans up after it.
2481 jermar 109
 */
2482 jermar 110
void fibril_main(void)
1113 palkovsky 111
{
2482 jermar 112
    fibril_t *f = __tcb_get()->fibril_data;
1129 palkovsky 113
 
2483 jermar 114
    /* Call the implementing function. */
2482 jermar 115
    f->retval = f->func(f->arg);
1113 palkovsky 116
 
2568 jermar 117
    fibril_switch(FIBRIL_FROM_DEAD);
2481 jermar 118
    /* not reached */
1113 palkovsky 119
}
120
 
2568 jermar 121
/** Switch from the current fibril.
1128 jermar 122
 *
2482 jermar 123
 * If calling with FIBRIL_TO_MANAGER parameter, the async_futex should be
1427 palkovsky 124
 * held.
125
 *
2483 jermar 126
 * @param stype     Switch type. One of FIBRIL_PREEMPT, FIBRIL_TO_MANAGER,
2482 jermar 127
 *          FIBRIL_FROM_MANAGER, FIBRIL_FROM_DEAD. The parameter
128
 *          describes the circumstances of the switch.
129
 * @return      Return 0 if there is no ready fibril,
2481 jermar 130
 *          return 1 otherwise.
1128 jermar 131
 */
2568 jermar 132
int fibril_switch(fibril_switch_type_t stype)
1113 palkovsky 133
{
2482 jermar 134
    fibril_t *srcf, *dstf;
1392 palkovsky 135
    int retval = 0;
136
 
2482 jermar 137
    futex_down(&fibril_futex);
1113 palkovsky 138
 
2482 jermar 139
    if (stype == FIBRIL_PREEMPT && list_empty(&ready_list))
1392 palkovsky 140
        goto ret_0;
1113 palkovsky 141
 
2482 jermar 142
    if (stype == FIBRIL_FROM_MANAGER) {
1610 palkovsky 143
        if (list_empty(&ready_list) && list_empty(&serialized_list))
144
            goto ret_0;
2481 jermar 145
        /*
2483 jermar 146
         * Do not preempt if there is not sufficient count of fibril
2481 jermar 147
         * managers.
148
         */
2568 jermar 149
        if (list_empty(&serialized_list) &&
150
            fibrils_in_manager <= serialized_fibrils) {
1610 palkovsky 151
            goto ret_0;
152
        }
1392 palkovsky 153
    }
1407 palkovsky 154
    /* If we are going to manager and none exists, create it */
2482 jermar 155
    if (stype == FIBRIL_TO_MANAGER || stype == FIBRIL_FROM_DEAD) {
1610 palkovsky 156
        while (list_empty(&manager_list)) {
2482 jermar 157
            futex_up(&fibril_futex);
1610 palkovsky 158
            async_create_manager();
2482 jermar 159
            futex_down(&fibril_futex);
1610 palkovsky 160
        }
1427 palkovsky 161
    }
1610 palkovsky 162
 
2482 jermar 163
    srcf = __tcb_get()->fibril_data;
164
    if (stype != FIBRIL_FROM_DEAD) {
1610 palkovsky 165
        /* Save current state */
2482 jermar 166
        if (!context_save(&srcf->ctx)) {
1610 palkovsky 167
            if (serialization_count)
2482 jermar 168
                srcf->flags &= ~FIBRIL_SERIALIZED;
169
            if (srcf->clean_after_me) {
2481 jermar 170
                /*
2482 jermar 171
                 * Cleanup after the dead fibril from which we
172
                 * restored context here.
2481 jermar 173
                 */
2568 jermar 174
                void *stack = srcf->clean_after_me->stack;
175
                if (stack) {
176
                    /*
177
                     * This check is necessary because a
178
                     * thread could have exited like a
179
                     * normal fibril using the
180
                     * FIBRIL_FROM_DEAD switch type. In that
181
                     * case, its fibril will not have the
182
                     * stack member filled.
183
                     */
184
                    free(stack);
185
                }
2482 jermar 186
                fibril_teardown(srcf->clean_after_me);
187
                srcf->clean_after_me = NULL;
2481 jermar 188
            }
189
            return 1;   /* futex_up already done here */
1610 palkovsky 190
        }
1392 palkovsky 191
 
2481 jermar 192
        /* Save myself to the correct run list */
2482 jermar 193
        if (stype == FIBRIL_PREEMPT)
194
            list_append(&srcf->link, &ready_list);
195
        else if (stype == FIBRIL_FROM_MANAGER) {
196
            list_append(&srcf->link, &manager_list);
197
            fibrils_in_manager--;
2481 jermar 198
        } else {   
199
            /*
2482 jermar 200
             * If stype == FIBRIL_TO_MANAGER, don't put ourselves to
2481 jermar 201
             * any list, we should already be somewhere, or we will
202
             * be lost.
203
             */
204
        }
205
    }
2568 jermar 206
 
2482 jermar 207
    /* Choose a new fibril to run */
208
    if (stype == FIBRIL_TO_MANAGER || stype == FIBRIL_FROM_DEAD) {
209
        dstf = list_get_instance(manager_list.next, fibril_t, link);
210
        if (serialization_count && stype == FIBRIL_TO_MANAGER) {
2483 jermar 211
            serialized_fibrils++;
2482 jermar 212
            srcf->flags |= FIBRIL_SERIALIZED;
1610 palkovsky 213
        }
2482 jermar 214
        fibrils_in_manager++;
2481 jermar 215
 
2568 jermar 216
        if (stype == FIBRIL_FROM_DEAD)
2482 jermar 217
            dstf->clean_after_me = srcf;
1610 palkovsky 218
    } else {
219
        if (!list_empty(&serialized_list)) {
2482 jermar 220
            dstf = list_get_instance(serialized_list.next, fibril_t,
221
                link);
2483 jermar 222
            serialized_fibrils--;
2481 jermar 223
        } else {
2482 jermar 224
            dstf = list_get_instance(ready_list.next, fibril_t,
225
                link);
2481 jermar 226
        }
1610 palkovsky 227
    }
2482 jermar 228
    list_remove(&dstf->link);
1113 palkovsky 229
 
2482 jermar 230
    futex_up(&fibril_futex);
231
    context_restore(&dstf->ctx);
2481 jermar 232
    /* not reached */
1392 palkovsky 233
 
234
ret_0:
2482 jermar 235
    futex_up(&fibril_futex);
1392 palkovsky 236
    return retval;
1113 palkovsky 237
}
238
 
2482 jermar 239
/** Create a new fibril.
1113 palkovsky 240
 *
2482 jermar 241
 * @param func      Implementing function of the new fibril.
2481 jermar 242
 * @param arg       Argument to pass to func.
1128 jermar 243
 *
2482 jermar 244
 * @return      Return 0 on failure or TLS of the new fibril.
1113 palkovsky 245
 */
2482 jermar 246
fid_t fibril_create(int (*func)(void *), void *arg)
1113 palkovsky 247
{
2482 jermar 248
    fibril_t *f;
1113 palkovsky 249
 
2482 jermar 250
    f = fibril_setup();
251
    if (!f)
1129 palkovsky 252
        return 0;
2482 jermar 253
    f->stack = (char *) malloc(FIBRIL_INITIAL_STACK_PAGES_NO *
2481 jermar 254
        getpagesize());
2482 jermar 255
    if (!f->stack) {
256
        fibril_teardown(f);
1113 palkovsky 257
        return 0;
258
    }
2568 jermar 259
 
260
    f->func = func;
2482 jermar 261
    f->arg = arg;
1113 palkovsky 262
 
2482 jermar 263
    context_save(&f->ctx);
264
    context_set(&f->ctx, FADDR(fibril_main), f->stack,
265
        FIBRIL_INITIAL_STACK_PAGES_NO * getpagesize(), f->tcb);
1113 palkovsky 266
 
2482 jermar 267
    return (fid_t) f;
1392 palkovsky 268
}
269
 
2482 jermar 270
/** Add a fibril to the ready list.
2481 jermar 271
 *
2492 jermar 272
 * @param fid       Pinter to the fibril structure of the fibril to be
273
 *          added.
2481 jermar 274
 */
2482 jermar 275
void fibril_add_ready(fid_t fid)
1392 palkovsky 276
{
2482 jermar 277
    fibril_t *f;
1392 palkovsky 278
 
2482 jermar 279
    f = (fibril_t *) fid;
280
    futex_down(&fibril_futex);
281
    if ((f->flags & FIBRIL_SERIALIZED))
282
        list_append(&f->link, &serialized_list);
1610 palkovsky 283
    else
2482 jermar 284
        list_append(&f->link, &ready_list);
285
    futex_up(&fibril_futex);
1392 palkovsky 286
}
1113 palkovsky 287
 
2482 jermar 288
/** Add a fibril to the manager list.
2481 jermar 289
 *
2482 jermar 290
 * @param fid       Pinter to the fibril structure of the fibril to be added.
2481 jermar 291
 */
2482 jermar 292
void fibril_add_manager(fid_t fid)
1392 palkovsky 293
{
2482 jermar 294
    fibril_t *f;
1392 palkovsky 295
 
2482 jermar 296
    f = (fibril_t *) fid;
1392 palkovsky 297
 
2482 jermar 298
    futex_down(&fibril_futex);
299
    list_append(&f->link, &manager_list);
300
    futex_up(&fibril_futex);
1113 palkovsky 301
}
1392 palkovsky 302
 
2482 jermar 303
/** Remove one manager from the manager list. */
304
void fibril_remove_manager(void)
1392 palkovsky 305
{
2482 jermar 306
    futex_down(&fibril_futex);
1392 palkovsky 307
    if (list_empty(&manager_list)) {
2482 jermar 308
        futex_up(&fibril_futex);
1392 palkovsky 309
        return;
310
    }
311
    list_remove(manager_list.next);
2482 jermar 312
    futex_up(&fibril_futex);
1392 palkovsky 313
}
1427 palkovsky 314
 
2482 jermar 315
/** Return fibril id of the currently running fibril.
2481 jermar 316
 *
2482 jermar 317
 * @return      Fibril ID of the currently running pseudo thread.
2481 jermar 318
 */
2482 jermar 319
fid_t fibril_get_id(void)
1427 palkovsky 320
{
2482 jermar 321
    return (fid_t) __tcb_get()->fibril_data;
1427 palkovsky 322
}
1610 palkovsky 323
 
324
/** Disable preemption
325
 *
2482 jermar 326
 * If the fibril wants to send several message in a row and does not want to be
2481 jermar 327
 * preempted, it should start async_serialize_start() in the beginning of
328
 * communication and async_serialize_end() in the end. If it is a true
329
 * multithreaded application, it should protect the communication channel by a
330
 * futex as well. Interrupt messages can still be preempted.
1610 palkovsky 331
 */
2482 jermar 332
void fibril_inc_sercount(void)
1610 palkovsky 333
{
334
    serialization_count++;
335
}
336
 
2481 jermar 337
/** Restore the preemption counter to the previous state. */
2482 jermar 338
void fibril_dec_sercount(void)
1610 palkovsky 339
{
340
    serialization_count--;
341
}
1653 cejka 342
 
1719 decky 343
/** @}
1653 cejka 344
 */
2481 jermar 345