source: mainline/uspace/lib/c/generic/fibril.c@ b272c67a

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since b272c67a was 6d87dce, checked in by Jakub Jermar <jakub@…>, 9 years ago

Use raw fibril synchronization in fibril_setup()

With some configurations, fibril_lock/unlock() may attempt to access TLS.
We therefore need to be careful in fibril_setup(), which is called before
tcb_setup(), to use fibril_down/up() instead.
  • Property mode set to 100644
File size: 8.6 KB
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1/*
2 * Copyright (c) 2006 Ondrej Palkovsky
3 * Copyright (c) 2007 Jakub Jermar
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
30/** @addtogroup libc
31 * @{
32 */
33/** @file
34 */
35
36#include <adt/list.h>
37#include <fibril.h>
38#include <thread.h>
39#include <stack.h>
40#include <tls.h>
41#include <malloc.h>
42#include <abi/mm/as.h>
43#include <as.h>
44#include <unistd.h>
45#include <stdio.h>
46#include <libarch/barrier.h>
47#include <libarch/faddr.h>
48#include <futex.h>
49#include <assert.h>
50#include <async.h>
51
52#ifdef FUTEX_UPGRADABLE
53#include <rcu.h>
54#endif
55
56/**
57 * This futex serializes access to ready_list,
58 * manager_list and fibril_list.
59 */
60static futex_t fibril_futex = FUTEX_INITIALIZER;
61
62static LIST_INITIALIZE(ready_list);
63static LIST_INITIALIZE(manager_list);
64static LIST_INITIALIZE(fibril_list);
65
66/** Function that spans the whole life-cycle of a fibril.
67 *
68 * Each fibril begins execution in this function. Then the function implementing
69 * the fibril logic is called. After its return, the return value is saved.
70 * The fibril then switches to another fibril, which cleans up after it.
71 *
72 */
73static void fibril_main(void)
74{
75 fibril_t *fibril = __tcb_get()->fibril_data;
76
77#ifdef FUTEX_UPGRADABLE
78 rcu_register_fibril();
79#endif
80
81 /* Call the implementing function. */
82 fibril->retval = fibril->func(fibril->arg);
83
84 futex_down(&async_futex);
85 fibril_switch(FIBRIL_FROM_DEAD);
86 /* Not reached */
87}
88
89/** Setup fibril information into TCB structure
90 *
91 */
92fibril_t *fibril_setup(void)
93{
94 tcb_t *tcb = tls_make();
95 if (!tcb)
96 return NULL;
97
98 fibril_t *fibril = malloc(sizeof(fibril_t));
99 if (!fibril) {
100 tls_free(tcb);
101 return NULL;
102 }
103
104 tcb->fibril_data = fibril;
105 fibril->tcb = tcb;
106
107 fibril->func = NULL;
108 fibril->arg = NULL;
109 fibril->stack = NULL;
110 fibril->clean_after_me = NULL;
111 fibril->retval = 0;
112 fibril->flags = 0;
113
114 fibril->waits_for = NULL;
115
116 /*
117 * We are called before __tcb_set(), so we need to use
118 * futex_down/up() instead of futex_lock/unlock() that
119 * may attempt to access TLS.
120 */
121 futex_down(&fibril_futex);
122 list_append(&fibril->all_link, &fibril_list);
123 futex_up(&fibril_futex);
124
125 return fibril;
126}
127
128void fibril_teardown(fibril_t *fibril, bool locked)
129{
130 if (!locked)
131 futex_lock(&fibril_futex);
132 list_remove(&fibril->all_link);
133 if (!locked)
134 futex_unlock(&fibril_futex);
135 tls_free(fibril->tcb);
136 free(fibril);
137}
138
139/** Switch from the current fibril.
140 *
141 * If stype is FIBRIL_TO_MANAGER or FIBRIL_FROM_DEAD, the async_futex must
142 * be held.
143 *
144 * @param stype Switch type. One of FIBRIL_PREEMPT, FIBRIL_TO_MANAGER,
145 * FIBRIL_FROM_MANAGER, FIBRIL_FROM_DEAD. The parameter
146 * describes the circumstances of the switch.
147 *
148 * @return 0 if there is no ready fibril,
149 * @return 1 otherwise.
150 *
151 */
152int fibril_switch(fibril_switch_type_t stype)
153{
154 futex_lock(&fibril_futex);
155
156 switch (stype) {
157 case FIBRIL_PREEMPT:
158 case FIBRIL_FROM_MANAGER:
159 if (list_empty(&ready_list)) {
160 futex_unlock(&fibril_futex);
161 return 0;
162 }
163 break;
164 case FIBRIL_TO_MANAGER:
165 case FIBRIL_FROM_DEAD:
166 /* Make sure the async_futex is held. */
167 assert((atomic_signed_t) async_futex.val.count <= 0);
168
169 /* If we are going to manager and none exists, create it */
170 while (list_empty(&manager_list)) {
171 futex_unlock(&fibril_futex);
172 async_create_manager();
173 futex_lock(&fibril_futex);
174 }
175 break;
176 }
177
178 fibril_t *srcf = __tcb_get()->fibril_data;
179 if (stype != FIBRIL_FROM_DEAD) {
180
181 /* Save current state */
182 if (!context_save(&srcf->ctx)) {
183 if (srcf->clean_after_me) {
184 /*
185 * Cleanup after the dead fibril from which we
186 * restored context here.
187 */
188 void *stack = srcf->clean_after_me->stack;
189 if (stack) {
190 /*
191 * This check is necessary because a
192 * thread could have exited like a
193 * normal fibril using the
194 * FIBRIL_FROM_DEAD switch type. In that
195 * case, its fibril will not have the
196 * stack member filled.
197 */
198 as_area_destroy(stack);
199 }
200 fibril_teardown(srcf->clean_after_me, true);
201 srcf->clean_after_me = NULL;
202 }
203
204 return 1; /* futex_unlock already done here */
205 }
206
207 /* Put the current fibril into the correct run list */
208 switch (stype) {
209 case FIBRIL_PREEMPT:
210 list_append(&srcf->link, &ready_list);
211 break;
212 case FIBRIL_FROM_MANAGER:
213 list_append(&srcf->link, &manager_list);
214 break;
215 default:
216 assert(stype == FIBRIL_TO_MANAGER);
217
218 /*
219 * Don't put the current fibril into any list, it should
220 * already be somewhere, or it will be lost.
221 */
222 break;
223 }
224 }
225
226 fibril_t *dstf;
227
228 /* Choose a new fibril to run */
229 switch (stype) {
230 case FIBRIL_TO_MANAGER:
231 case FIBRIL_FROM_DEAD:
232 dstf = list_get_instance(list_first(&manager_list), fibril_t,
233 link);
234
235 if (stype == FIBRIL_FROM_DEAD)
236 dstf->clean_after_me = srcf;
237 break;
238 default:
239 dstf = list_get_instance(list_first(&ready_list), fibril_t,
240 link);
241 break;
242 }
243
244 list_remove(&dstf->link);
245
246 futex_unlock(&fibril_futex);
247
248#ifdef FUTEX_UPGRADABLE
249 if (stype == FIBRIL_FROM_DEAD) {
250 rcu_deregister_fibril();
251 }
252#endif
253
254 context_restore(&dstf->ctx);
255 /* not reached */
256}
257
258/** Create a new fibril.
259 *
260 * @param func Implementing function of the new fibril.
261 * @param arg Argument to pass to func.
262 * @param stksz Stack size in bytes.
263 *
264 * @return 0 on failure or TLS of the new fibril.
265 *
266 */
267fid_t fibril_create_generic(int (*func)(void *), void *arg, size_t stksz)
268{
269 fibril_t *fibril;
270
271 fibril = fibril_setup();
272 if (fibril == NULL)
273 return 0;
274
275 size_t stack_size = (stksz == FIBRIL_DFLT_STK_SIZE) ?
276 stack_size_get() : stksz;
277 fibril->stack = as_area_create((void *) -1, stack_size,
278 AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE | AS_AREA_GUARD |
279 AS_AREA_LATE_RESERVE);
280 if (fibril->stack == (void *) -1) {
281 fibril_teardown(fibril, false);
282 return 0;
283 }
284
285 fibril->func = func;
286 fibril->arg = arg;
287
288 context_save(&fibril->ctx);
289 context_set(&fibril->ctx, FADDR(fibril_main), fibril->stack,
290 stack_size, fibril->tcb);
291
292 return (fid_t) fibril;
293}
294
295/** Delete a fibril that has never run.
296 *
297 * Free resources of a fibril that has been created with fibril_create()
298 * but never readied using fibril_add_ready().
299 *
300 * @param fid Pointer to the fibril structure of the fibril to be
301 * added.
302 */
303void fibril_destroy(fid_t fid)
304{
305 fibril_t *fibril = (fibril_t *) fid;
306
307 as_area_destroy(fibril->stack);
308 fibril_teardown(fibril, false);
309}
310
311/** Add a fibril to the ready list.
312 *
313 * @param fid Pointer to the fibril structure of the fibril to be
314 * added.
315 *
316 */
317void fibril_add_ready(fid_t fid)
318{
319 fibril_t *fibril = (fibril_t *) fid;
320
321 futex_lock(&fibril_futex);
322 list_append(&fibril->link, &ready_list);
323 futex_unlock(&fibril_futex);
324}
325
326/** Add a fibril to the manager list.
327 *
328 * @param fid Pointer to the fibril structure of the fibril to be
329 * added.
330 *
331 */
332void fibril_add_manager(fid_t fid)
333{
334 fibril_t *fibril = (fibril_t *) fid;
335
336 futex_lock(&fibril_futex);
337 list_append(&fibril->link, &manager_list);
338 futex_unlock(&fibril_futex);
339}
340
341/** Remove one manager from the manager list. */
342void fibril_remove_manager(void)
343{
344 futex_lock(&fibril_futex);
345 if (!list_empty(&manager_list))
346 list_remove(list_first(&manager_list));
347 futex_unlock(&fibril_futex);
348}
349
350/** Return fibril id of the currently running fibril.
351 *
352 * @return fibril ID of the currently running fibril.
353 *
354 */
355fid_t fibril_get_id(void)
356{
357 return (fid_t) __tcb_get()->fibril_data;
358}
359
360/** @}
361 */
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