1/* Suspend until termination of a requests.
2 Copyright (C) 1997-2020 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20
21/* We use an UGLY hack to prevent gcc from finding us cheating. The
22 implementations of aio_suspend and aio_suspend64 are identical and so
23 we want to avoid code duplication by using aliases. But gcc sees
24 the different parameter lists and prints a warning. We define here
25 a function so that aio_suspend64 has no prototype. */
26#define aio_suspend64 XXX
27#include <aio.h>
28/* And undo the hack. */
29#undef aio_suspend64
30
31#include <assert.h>
32#include <errno.h>
33#include <stdbool.h>
34#include <stdlib.h>
35#include <sys/time.h>
36
37#include <libc-lock.h>
38#include <aio_misc.h>
39
40
41struct clparam
42{
43 const struct aiocb *const *list;
44 struct waitlist *waitlist;
45 struct requestlist **requestlist;
46#ifndef DONT_NEED_AIO_MISC_COND
47 pthread_cond_t *cond;
48#endif
49 int nent;
50};
51
52
53static void
54cleanup (void *arg)
55{
56#ifdef DONT_NEED_AIO_MISC_COND
57 /* Acquire the mutex. If pthread_cond_*wait is used this would
58 happen implicitly. */
59 pthread_mutex_lock (&__aio_requests_mutex);
60#endif
61
62 const struct clparam *param = (const struct clparam *) arg;
63
64 /* Now remove the entry in the waiting list for all requests
65 which didn't terminate. */
66 int cnt = param->nent;
67 while (cnt-- > 0)
68 if (param->list[cnt] != NULL
69 && param->list[cnt]->__error_code == EINPROGRESS)
70 {
71 struct waitlist **listp;
72
73 assert (param->requestlist[cnt] != NULL);
74
75 /* There is the chance that we cannot find our entry anymore. This
76 could happen if the request terminated and restarted again. */
77 listp = &param->requestlist[cnt]->waiting;
78 while (*listp != NULL && *listp != &param->waitlist[cnt])
79 listp = &(*listp)->next;
80
81 if (*listp != NULL)
82 *listp = (*listp)->next;
83 }
84
85#ifndef DONT_NEED_AIO_MISC_COND
86 /* Release the conditional variable. */
87 (void) pthread_cond_destroy (param->cond);
88#endif
89
90 /* Release the mutex. */
91 pthread_mutex_unlock (&__aio_requests_mutex);
92}
93
94#ifdef DONT_NEED_AIO_MISC_COND
95static int
96__attribute__ ((noinline))
97do_aio_misc_wait (unsigned int *cntr, const struct timespec *timeout)
98{
99 int result = 0;
100
101 AIO_MISC_WAIT (result, *cntr, timeout, 1);
102
103 return result;
104}
105#endif
106
107int
108aio_suspend (const struct aiocb *const list[], int nent,
109 const struct timespec *timeout)
110{
111 if (__glibc_unlikely (nent < 0))
112 {
113 __set_errno (EINVAL);
114 return -1;
115 }
116
117 struct waitlist waitlist[nent];
118 struct requestlist *requestlist[nent];
119#ifndef DONT_NEED_AIO_MISC_COND
120 pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
121#endif
122 int cnt;
123 bool any = false;
124 int result = 0;
125 unsigned int cntr = 1;
126
127 /* Request the mutex. */
128 pthread_mutex_lock (&__aio_requests_mutex);
129
130 /* There is not yet a finished request. Signal the request that
131 we are working for it. */
132 for (cnt = 0; cnt < nent; ++cnt)
133 if (list[cnt] != NULL)
134 {
135 if (list[cnt]->__error_code == EINPROGRESS)
136 {
137 requestlist[cnt] = __aio_find_req ((aiocb_union *) list[cnt]);
138
139 if (requestlist[cnt] != NULL)
140 {
141#ifndef DONT_NEED_AIO_MISC_COND
142 waitlist[cnt].cond = &cond;
143#endif
144 waitlist[cnt].result = NULL;
145 waitlist[cnt].next = requestlist[cnt]->waiting;
146 waitlist[cnt].counterp = &cntr;
147 waitlist[cnt].sigevp = NULL;
148 requestlist[cnt]->waiting = &waitlist[cnt];
149 any = true;
150 }
151 else
152 /* We will never suspend. */
153 break;
154 }
155 else
156 /* We will never suspend. */
157 break;
158 }
159
160
161 /* Only if none of the entries is NULL or finished to be wait. */
162 if (cnt == nent && any)
163 {
164 struct clparam clparam =
165 {
166 .list = list,
167 .waitlist = waitlist,
168 .requestlist = requestlist,
169#ifndef DONT_NEED_AIO_MISC_COND
170 .cond = &cond,
171#endif
172 .nent = nent
173 };
174
175 pthread_cleanup_push (cleanup, &clparam);
176
177#ifdef DONT_NEED_AIO_MISC_COND
178 result = do_aio_misc_wait (&cntr, timeout);
179#else
180 if (timeout == NULL)
181 result = pthread_cond_wait (&cond, &__aio_requests_mutex);
182 else
183 {
184 /* We have to convert the relative timeout value into an
185 absolute time value with pthread_cond_timedwait expects. */
186 struct timespec now;
187 struct timespec abstime;
188
189 __clock_gettime (CLOCK_REALTIME, &now);
190 abstime.tv_nsec = timeout->tv_nsec + now.tv_nsec;
191 abstime.tv_sec = timeout->tv_sec + now.tv_sec;
192 if (abstime.tv_nsec >= 1000000000)
193 {
194 abstime.tv_nsec -= 1000000000;
195 abstime.tv_sec += 1;
196 }
197
198 result = pthread_cond_timedwait (&cond, &__aio_requests_mutex,
199 &abstime);
200 }
201#endif
202
203 pthread_cleanup_pop (0);
204 }
205
206 /* Now remove the entry in the waiting list for all requests
207 which didn't terminate. */
208 while (cnt-- > 0)
209 if (list[cnt] != NULL && list[cnt]->__error_code == EINPROGRESS)
210 {
211 struct waitlist **listp;
212
213 assert (requestlist[cnt] != NULL);
214
215 /* There is the chance that we cannot find our entry anymore. This
216 could happen if the request terminated and restarted again. */
217 listp = &requestlist[cnt]->waiting;
218 while (*listp != NULL && *listp != &waitlist[cnt])
219 listp = &(*listp)->next;
220
221 if (*listp != NULL)
222 *listp = (*listp)->next;
223 }
224
225#ifndef DONT_NEED_AIO_MISC_COND
226 /* Release the conditional variable. */
227 if (__glibc_unlikely (pthread_cond_destroy (&cond) != 0))
228 /* This must never happen. */
229 abort ();
230#endif
231
232 if (result != 0)
233 {
234#ifndef DONT_NEED_AIO_MISC_COND
235 /* An error occurred. Possibly it's ETIMEDOUT. We have to translate
236 the timeout error report of `pthread_cond_timedwait' to the
237 form expected from `aio_suspend'. */
238 if (result == ETIMEDOUT)
239 __set_errno (EAGAIN);
240 else
241#endif
242 __set_errno (result);
243
244 result = -1;
245 }
246
247 /* Release the mutex. */
248 pthread_mutex_unlock (&__aio_requests_mutex);
249
250 return result;
251}
252
253weak_alias (aio_suspend, aio_suspend64)
254