]>
Commit | Line | Data |
---|---|---|
f7a9f785 | 1 | /* Copyright (C) 2004-2016 Free Software Foundation, Inc. |
1b82c6c7 | 2 | This file is part of the GNU C Library. |
08192659 | 3 | Contribute by Ulrich Drepper <drepper@redhat.com>, 2004. |
1b82c6c7 UD |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Lesser General Public | |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
9 | ||
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
59ba27a6 PE |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ | |
1b82c6c7 | 18 | |
08192659 | 19 | #include <assert.h> |
1b82c6c7 | 20 | #include <errno.h> |
08192659 | 21 | #include <fcntl.h> |
1b82c6c7 | 22 | #include <mqueue.h> |
08192659 RM |
23 | #include <pthread.h> |
24 | #include <signal.h> | |
25 | #include <stdlib.h> | |
26 | #include <string.h> | |
1b82c6c7 | 27 | #include <sysdep.h> |
08192659 RM |
28 | #include <unistd.h> |
29 | #include <sys/socket.h> | |
30 | #include <not-cancel.h> | |
31 | #include <nptl/pthreadP.h> | |
32 | ||
1b82c6c7 UD |
33 | |
34 | #ifdef __NR_mq_notify | |
35 | ||
08192659 RM |
36 | /* Defined in the kernel headers: */ |
37 | #define NOTIFY_COOKIE_LEN 32 /* Length of the cookie used. */ | |
38 | #define NOTIFY_WOKENUP 1 /* Code for notifcation. */ | |
39 | #define NOTIFY_REMOVED 2 /* Code for closed message queue | |
40 | of de-notifcation. */ | |
41 | ||
42 | ||
43 | /* Data structure for the queued notification requests. */ | |
44 | union notify_data | |
45 | { | |
46 | struct | |
47 | { | |
48 | void (*fct) (union sigval); /* The function to run. */ | |
49 | union sigval param; /* The parameter to pass. */ | |
50 | pthread_attr_t *attr; /* Attributes to create the thread with. */ | |
51 | /* NB: on 64-bit machines the struct as a size of 24 bytes. Which means | |
52 | byte 31 can still be used for returning the status. */ | |
53 | }; | |
54 | char raw[NOTIFY_COOKIE_LEN]; | |
55 | }; | |
56 | ||
57 | ||
58 | /* Keep track of the initialization. */ | |
59 | static pthread_once_t once = PTHREAD_ONCE_INIT; | |
60 | ||
61 | ||
62 | /* The netlink socket. */ | |
63 | static int netlink_socket = -1; | |
64 | ||
65 | ||
66 | /* Barrier used to make sure data passed to the new thread is not | |
67 | resused by the parent. */ | |
68 | static pthread_barrier_t notify_barrier; | |
69 | ||
70 | ||
71 | /* Modify the signal mask. We move this into a separate function so | |
72 | that the stack space needed for sigset_t is not deducted from what | |
73 | the thread can use. */ | |
74 | static int | |
75 | __attribute__ ((noinline)) | |
76 | change_sigmask (int how, sigset_t *oss) | |
77 | { | |
78 | sigset_t ss; | |
79 | sigfillset (&ss); | |
80 | return pthread_sigmask (how, &ss, oss); | |
81 | } | |
82 | ||
83 | ||
84 | /* The function used for the notification. */ | |
85 | static void * | |
86 | notification_function (void *arg) | |
87 | { | |
88 | /* Copy the function and parameter so that the parent thread can go | |
89 | on with its life. */ | |
90 | volatile union notify_data *data = (volatile union notify_data *) arg; | |
91 | void (*fct) (union sigval) = data->fct; | |
92 | union sigval param = data->param; | |
93 | ||
94 | /* Let the parent go. */ | |
90dd5913 | 95 | (void) __pthread_barrier_wait (¬ify_barrier); |
08192659 RM |
96 | |
97 | /* Make the thread detached. */ | |
98 | (void) pthread_detach (pthread_self ()); | |
99 | ||
100 | /* The parent thread has all signals blocked. This is probably a | |
101 | bit surprising for this thread. So we unblock all of them. */ | |
102 | (void) change_sigmask (SIG_UNBLOCK, NULL); | |
103 | ||
104 | /* Now run the user code. */ | |
105 | fct (param); | |
106 | ||
107 | /* And we are done. */ | |
108 | return NULL; | |
109 | } | |
110 | ||
111 | ||
112 | /* Helper thread. */ | |
113 | static void * | |
114 | helper_thread (void *arg) | |
115 | { | |
116 | while (1) | |
117 | { | |
118 | union notify_data data; | |
119 | ||
0595c984 JM |
120 | ssize_t n = __recv (netlink_socket, &data, sizeof (data), |
121 | MSG_NOSIGNAL | MSG_WAITALL); | |
08192659 RM |
122 | if (n < NOTIFY_COOKIE_LEN) |
123 | continue; | |
124 | ||
125 | if (data.raw[NOTIFY_COOKIE_LEN - 1] == NOTIFY_WOKENUP) | |
126 | { | |
127 | /* Just create the thread as instructed. There is no way to | |
128 | report a problem with creating a thread. */ | |
129 | pthread_t th; | |
130 | if (__builtin_expect (pthread_create (&th, data.attr, | |
131 | notification_function, &data) | |
132 | == 0, 0)) | |
133 | /* Since we passed a pointer to DATA to the new thread we have | |
134 | to wait until it is done with it. */ | |
90dd5913 | 135 | (void) __pthread_barrier_wait (¬ify_barrier); |
08192659 RM |
136 | } |
137 | else if (data.raw[NOTIFY_COOKIE_LEN - 1] == NOTIFY_REMOVED) | |
138 | /* The only state we keep is the copy of the thread attributes. */ | |
139 | free (data.attr); | |
140 | } | |
141 | return NULL; | |
142 | } | |
143 | ||
144 | ||
145 | static void | |
146 | reset_once (void) | |
147 | { | |
148 | once = PTHREAD_ONCE_INIT; | |
149 | } | |
150 | ||
151 | ||
152 | static void | |
153 | init_mq_netlink (void) | |
154 | { | |
155 | /* This code might be called a second time after fork(). The file | |
156 | descriptor is inherited from the parent. */ | |
157 | if (netlink_socket == -1) | |
158 | { | |
159 | /* Just a normal netlink socket, not bound. */ | |
0595c984 | 160 | netlink_socket = __socket (AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, 0); |
08192659 RM |
161 | /* No need to do more if we have no socket. */ |
162 | if (netlink_socket == -1) | |
163 | return; | |
164 | } | |
165 | ||
166 | int err = 1; | |
167 | ||
168 | /* Initialize the barrier. */ | |
90dd5913 | 169 | if (__builtin_expect (__pthread_barrier_init (¬ify_barrier, NULL, 2) == 0, |
08192659 RM |
170 | 0)) |
171 | { | |
172 | /* Create the helper thread. */ | |
173 | pthread_attr_t attr; | |
174 | (void) pthread_attr_init (&attr); | |
175 | (void) pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED); | |
176 | /* We do not need much stack space, the bare minimum will be enough. */ | |
177 | (void) pthread_attr_setstacksize (&attr, __pthread_get_minstack (&attr)); | |
178 | ||
179 | /* Temporarily block all signals so that the newly created | |
180 | thread inherits the mask. */ | |
181 | sigset_t oss; | |
182 | int have_no_oss = change_sigmask (SIG_BLOCK, &oss); | |
183 | ||
184 | pthread_t th; | |
185 | err = pthread_create (&th, &attr, helper_thread, NULL); | |
186 | ||
187 | /* Reset the signal mask. */ | |
188 | if (!have_no_oss) | |
189 | pthread_sigmask (SIG_SETMASK, &oss, NULL); | |
190 | ||
191 | (void) pthread_attr_destroy (&attr); | |
192 | ||
193 | if (err == 0) | |
194 | { | |
195 | static int added_atfork; | |
196 | ||
197 | if (added_atfork == 0 | |
198 | && pthread_atfork (NULL, NULL, reset_once) != 0) | |
199 | { | |
200 | /* The child thread will call recv() which is a | |
201 | cancellation point. */ | |
202 | (void) pthread_cancel (th); | |
203 | err = 1; | |
204 | } | |
205 | else | |
206 | added_atfork = 1; | |
207 | } | |
208 | } | |
209 | ||
210 | if (err != 0) | |
211 | { | |
212 | close_not_cancel_no_status (netlink_socket); | |
213 | netlink_socket = -1; | |
214 | } | |
215 | } | |
216 | ||
217 | ||
1b82c6c7 UD |
218 | /* Register notification upon message arrival to an empty message queue |
219 | MQDES. */ | |
220 | int | |
221 | mq_notify (mqd_t mqdes, const struct sigevent *notification) | |
222 | { | |
08192659 RM |
223 | /* Make sure the type is correctly defined. */ |
224 | assert (sizeof (union notify_data) == NOTIFY_COOKIE_LEN); | |
225 | ||
226 | /* Special treatment needed for SIGEV_THREAD. */ | |
227 | if (notification == NULL || notification->sigev_notify != SIGEV_THREAD) | |
228 | return INLINE_SYSCALL (mq_notify, 2, mqdes, notification); | |
229 | ||
230 | /* The kernel cannot directly start threads. This will have to be | |
231 | done at userlevel. Since we cannot start threads from signal | |
232 | handlers we have to create a dedicated thread which waits for | |
233 | notifications for arriving messages and creates threads in | |
234 | response. */ | |
235 | ||
236 | /* Initialize only once. */ | |
237 | pthread_once (&once, init_mq_netlink); | |
238 | ||
239 | /* If we cannot create the netlink socket we cannot provide | |
240 | SIGEV_THREAD support. */ | |
241 | if (__glibc_unlikely (netlink_socket == -1)) | |
1b82c6c7 UD |
242 | { |
243 | __set_errno (ENOSYS); | |
244 | return -1; | |
245 | } | |
08192659 RM |
246 | |
247 | /* Create the cookie. It will hold almost all the state. */ | |
248 | union notify_data data; | |
249 | memset (&data, '\0', sizeof (data)); | |
250 | data.fct = notification->sigev_notify_function; | |
251 | data.param = notification->sigev_value; | |
252 | ||
253 | if (notification->sigev_notify_attributes != NULL) | |
254 | { | |
255 | /* The thread attribute has to be allocated separately. */ | |
256 | data.attr = (pthread_attr_t *) malloc (sizeof (pthread_attr_t)); | |
257 | if (data.attr == NULL) | |
258 | return -1; | |
259 | ||
260 | memcpy (data.attr, notification->sigev_notify_attributes, | |
261 | sizeof (pthread_attr_t)); | |
262 | } | |
263 | ||
264 | /* Construct the new request. */ | |
265 | struct sigevent se; | |
266 | se.sigev_notify = SIGEV_THREAD; | |
267 | se.sigev_signo = netlink_socket; | |
268 | se.sigev_value.sival_ptr = &data; | |
269 | ||
270 | /* Tell the kernel. */ | |
271 | int retval = INLINE_SYSCALL (mq_notify, 2, mqdes, &se); | |
272 | ||
273 | /* If it failed, free the allocated memory. */ | |
274 | if (__glibc_unlikely (retval != 0)) | |
275 | free (data.attr); | |
276 | ||
277 | return retval; | |
1b82c6c7 UD |
278 | } |
279 | ||
280 | #else | |
2826ac7e | 281 | # include <rt/mq_notify.c> |
1b82c6c7 | 282 | #endif |