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d4abeca5 | 1 | /* sem_post -- post to a POSIX semaphore. Generic futex-using version. |
688903eb | 2 | Copyright (C) 2003-2018 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> | |
a2f0363f | 26 | #include <futex-internal.h> |
b01fe5f7 UD |
27 | |
28 | #include <shlib-compat.h> | |
29 | ||
d4abeca5 DM |
30 | |
31 | /* See sem_wait for an explanation of the algorithm. */ | |
b01fe5f7 UD |
32 | int |
33 | __new_sem_post (sem_t *sem) | |
34 | { | |
d4abeca5 DM |
35 | struct new_sem *isem = (struct new_sem *) sem; |
36 | int private = isem->private; | |
37 | unsigned int v; | |
b01fe5f7 | 38 | |
88ed594f | 39 | __sparc32_atomic_do_lock24 (&isem->pad); |
d4abeca5 DM |
40 | |
41 | v = isem->value; | |
88ed594f | 42 | if ((v >> SEM_VALUE_SHIFT) == SEM_VALUE_MAX) |
e4720b0e | 43 | { |
88ed594f | 44 | __sparc32_atomic_do_unlock24 (&isem->pad); |
d4abeca5 DM |
45 | |
46 | __set_errno (EOVERFLOW); | |
47 | return -1; | |
e4720b0e | 48 | } |
d4abeca5 DM |
49 | isem->value = v + (1 << SEM_VALUE_SHIFT); |
50 | ||
88ed594f | 51 | __sparc32_atomic_do_unlock24 (&isem->pad); |
d4abeca5 DM |
52 | |
53 | if ((v & SEM_NWAITERS_MASK) != 0) | |
54 | futex_wake (&isem->value, 1, private); | |
55 | ||
e4720b0e JJ |
56 | return 0; |
57 | } | |
58 | versioned_symbol (libpthread, __new_sem_post, sem_post, GLIBC_2_1); | |
59 | ||
60 | ||
61 | #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1) | |
62 | int | |
63 | attribute_compat_text_section | |
64 | __old_sem_post (sem_t *sem) | |
65 | { | |
d4abeca5 | 66 | int *futex = (int *) sem; |
e4720b0e | 67 | |
d4abeca5 DM |
68 | /* We must need to synchronize with consumers of this token, so the atomic |
69 | increment must have release MO semantics. */ | |
70 | atomic_write_barrier (); | |
71 | (void) atomic_increment_val (futex); | |
72 | /* We always have to assume it is a shared semaphore. */ | |
73 | int err = lll_futex_wake (futex, 1, LLL_SHARED); | |
2c1d6172 | 74 | if (__builtin_expect (err, 0) < 0) |
b01fe5f7 | 75 | { |
2c1d6172 UD |
76 | __set_errno (-err); |
77 | return -1; | |
b01fe5f7 UD |
78 | } |
79 | return 0; | |
80 | } | |
b01fe5f7 UD |
81 | compat_symbol (libpthread, __old_sem_post, sem_post, GLIBC_2_0); |
82 | #endif |