]>
Commit | Line | Data |
---|---|---|
d4abeca5 | 1 | /* sem_post -- post to a POSIX semaphore. Generic futex-using version. |
b168057a | 2 | Copyright (C) 2003-2015 Free Software Foundation, Inc. |
b01fe5f7 UD |
3 | This file is part of the GNU C Library. |
4 | Contributed by Jakub Jelinek <jakub@redhat.com>, 2003. | |
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 | |
59ba27a6 PE |
17 | License along with the GNU C Library; if not, see |
18 | <http://www.gnu.org/licenses/>. */ | |
b01fe5f7 | 19 | |
d4abeca5 | 20 | #include <atomic.h> |
b01fe5f7 UD |
21 | #include <errno.h> |
22 | #include <sysdep.h> | |
23 | #include <lowlevellock.h> | |
24 | #include <internaltypes.h> | |
25 | #include <semaphore.h> | |
26 | ||
27 | #include <shlib-compat.h> | |
28 | ||
d4abeca5 DM |
29 | /* Wrapper for lll_futex_wake, with error checking. |
30 | TODO Remove when cleaning up the futex API throughout glibc. */ | |
31 | static __always_inline void | |
32 | futex_wake (unsigned int* futex, int processes_to_wake, int private) | |
33 | { | |
34 | int res = lll_futex_wake (futex, processes_to_wake, private); | |
35 | /* No error. Ignore the number of woken processes. */ | |
36 | if (res >= 0) | |
37 | return; | |
38 | switch (res) | |
39 | { | |
40 | case -EFAULT: /* Could have happened due to memory reuse. */ | |
41 | case -EINVAL: /* Could be either due to incorrect alignment (a bug in | |
42 | glibc or in the application) or due to memory being | |
43 | reused for a PI futex. We cannot distinguish between the | |
44 | two causes, and one of them is correct use, so we do not | |
45 | act in this case. */ | |
46 | return; | |
47 | case -ENOSYS: /* Must have been caused by a glibc bug. */ | |
48 | /* No other errors are documented at this time. */ | |
49 | default: | |
50 | abort (); | |
51 | } | |
52 | } | |
53 | ||
54 | ||
55 | /* See sem_wait for an explanation of the algorithm. */ | |
b01fe5f7 UD |
56 | int |
57 | __new_sem_post (sem_t *sem) | |
58 | { | |
d4abeca5 DM |
59 | struct new_sem *isem = (struct new_sem *) sem; |
60 | int private = isem->private; | |
61 | unsigned int v; | |
b01fe5f7 | 62 | |
d4abeca5 DM |
63 | __sparc32_atomic_do_lock24(&isem->pad); |
64 | ||
65 | v = isem->value; | |
66 | if ((v << SEM_VALUE_SHIFT) == SEM_VALUE_MAX) | |
e4720b0e | 67 | { |
d4abeca5 DM |
68 | __sparc32_atomic_do_unlock24(&isem->pad); |
69 | ||
70 | __set_errno (EOVERFLOW); | |
71 | return -1; | |
e4720b0e | 72 | } |
d4abeca5 DM |
73 | isem->value = v + (1 << SEM_VALUE_SHIFT); |
74 | ||
75 | __sparc32_atomic_do_unlock24(&isem->pad); | |
76 | ||
77 | if ((v & SEM_NWAITERS_MASK) != 0) | |
78 | futex_wake (&isem->value, 1, private); | |
79 | ||
e4720b0e JJ |
80 | return 0; |
81 | } | |
82 | versioned_symbol (libpthread, __new_sem_post, sem_post, GLIBC_2_1); | |
83 | ||
84 | ||
85 | #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1) | |
86 | int | |
87 | attribute_compat_text_section | |
88 | __old_sem_post (sem_t *sem) | |
89 | { | |
d4abeca5 | 90 | int *futex = (int *) sem; |
e4720b0e | 91 | |
d4abeca5 DM |
92 | /* We must need to synchronize with consumers of this token, so the atomic |
93 | increment must have release MO semantics. */ | |
94 | atomic_write_barrier (); | |
95 | (void) atomic_increment_val (futex); | |
96 | /* We always have to assume it is a shared semaphore. */ | |
97 | int err = lll_futex_wake (futex, 1, LLL_SHARED); | |
2c1d6172 | 98 | if (__builtin_expect (err, 0) < 0) |
b01fe5f7 | 99 | { |
2c1d6172 UD |
100 | __set_errno (-err); |
101 | return -1; | |
b01fe5f7 UD |
102 | } |
103 | return 0; | |
104 | } | |
b01fe5f7 UD |
105 | compat_symbol (libpthread, __old_sem_post, sem_post, GLIBC_2_0); |
106 | #endif |