9f6a73dad186b037ebaf0a4870a07fd4b7281c12
[kopensolaris-gnu/glibc.git] / nptl / sysdeps / pthread / gai_misc.h
1 /* Copyright (C) 2006 Free Software Foundation, Inc.
2    This file is part of the GNU C Library.
3
4    The GNU C Library is free software; you can redistribute it and/or
5    modify it under the terms of the GNU Lesser General Public
6    License as published by the Free Software Foundation; either
7    version 2.1 of the License, or (at your option) any later version.
8
9    The GNU C Library is distributed in the hope that it will be useful,
10    but WITHOUT ANY WARRANTY; without even the implied warranty of
11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12    Lesser General Public License for more details.
13
14    You should have received a copy of the GNU Lesser General Public
15    License along with the GNU C Library; if not, write to the Free
16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
17    02111-1307 USA.  */
18
19 /* We define a special synchronization primitive for AIO.  POSIX
20    conditional variables would be ideal but the pthread_cond_*wait
21    operations do not return on EINTR.  This is a requirement for
22    correct aio_suspend and lio_listio implementations.  */
23
24 #include <assert.h>
25 #include <signal.h>
26 #include <pthreadP.h>
27 #include <lowlevellock.h>
28
29 #define DONT_NEED_GAI_MISC_COND 1
30
31 #define GAI_MISC_NOTIFY(waitlist) \
32   do {                                                                        \
33     if (*waitlist->counterp > 0 && --*waitlist->counterp == 0)                \
34       lll_futex_wake (waitlist->counterp, 1);                                 \
35   } while (0)
36
37 #define GAI_MISC_WAIT(result, futex, timeout, cancel) \
38   do {                                                                        \
39     volatile int *futexaddr = &futex;                                         \
40     int oldval = futex;                                                       \
41                                                                               \
42     if (oldval != 0)                                                          \
43       {                                                                       \
44         pthread_mutex_unlock (&__gai_requests_mutex);                         \
45                                                                               \
46         int oldtype;                                                          \
47         if (cancel)                                                           \
48           oldtype = LIBC_CANCEL_ASYNC ();                                     \
49                                                                               \
50         int status;                                                           \
51         do                                                                    \
52           {                                                                   \
53             status = lll_futex_timed_wait (futexaddr, oldval, timeout);       \
54             if (status != -EWOULDBLOCK)                                       \
55               break;                                                          \
56                                                                               \
57             oldval = *futexaddr;                                              \
58           }                                                                   \
59         while (oldval != 0);                                                  \
60                                                                               \
61         if (cancel)                                                           \
62           LIBC_CANCEL_RESET (oldtype);                                        \
63                                                                               \
64         if (status == -EINTR)                                                 \
65           result = EINTR;                                                     \
66         else if (status == -ETIMEDOUT)                                        \
67           result = EAGAIN;                                                    \
68         else                                                                  \
69           assert (status == 0 || status == -EWOULDBLOCK);                     \
70                                                                               \
71         pthread_mutex_lock (&__gai_requests_mutex);                           \
72       }                                                                       \
73   } while (0)
74
75
76 #define gai_start_notify_thread __gai_start_notify_thread
77 #define gai_create_helper_thread __gai_create_helper_thread
78
79 extern inline void
80 __gai_start_notify_thread (void)
81 {
82   sigset_t ss;
83   sigemptyset (&ss);
84   INTERNAL_SYSCALL_DECL (err);
85   INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &ss, NULL, _NSIG / 8);
86 }
87
88 extern inline int
89 __gai_create_helper_thread (pthread_t *threadp, void *(*tf) (void *),
90                             void *arg)
91 {
92   pthread_attr_t attr;
93
94   /* Make sure the thread is created detached.  */
95   pthread_attr_init (&attr);
96   pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
97
98   /* The helper thread needs only very little resources.  */
99   (void) pthread_attr_setstacksize (&attr, PTHREAD_STACK_MIN);
100
101   /* Block all signals in the helper thread.  To do this thoroughly we
102      temporarily have to block all signals here.  */
103   sigset_t ss;
104   sigset_t oss;
105   sigfillset (&ss);
106   INTERNAL_SYSCALL_DECL (err);
107   INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &ss, &oss, _NSIG / 8);
108
109   int ret = pthread_create (threadp, &attr, tf, arg);
110
111   /* Restore the signal mask.  */
112   INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &oss, NULL,
113                     _NSIG / 8);
114
115   (void) pthread_attr_destroy (&attr);
116   return ret;
117 }
118
119 #include_next <gai_misc.h>