1 /* sem_post -- post to a POSIX semaphore. Generic futex-using version.
2 Copyright (C) 2003-2016 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Jakub Jelinek <jakub@redhat.com>, 2003.
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.
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.
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 <http://www.gnu.org/licenses/>. */
23 #include <lowlevellock.h>
24 #include <internaltypes.h>
25 #include <semaphore.h>
26 #include <futex-internal.h>
28 #include <shlib-compat.h>
31 /* See sem_wait for an explanation of the algorithm. */
33 __new_sem_post (sem_t
*sem
)
35 struct new_sem
*isem
= (struct new_sem
*) sem
;
36 int private = isem
->private;
39 __sparc32_atomic_do_lock24 (&isem
->pad
);
42 if ((v
>> SEM_VALUE_SHIFT
) == SEM_VALUE_MAX
)
44 __sparc32_atomic_do_unlock24 (&isem
->pad
);
46 __set_errno (EOVERFLOW
);
49 isem
->value
= v
+ (1 << SEM_VALUE_SHIFT
);
51 __sparc32_atomic_do_unlock24 (&isem
->pad
);
53 if ((v
& SEM_NWAITERS_MASK
) != 0)
54 futex_wake (&isem
->value
, 1, private);
58 versioned_symbol (libpthread
, __new_sem_post
, sem_post
, GLIBC_2_1
);
61 #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
63 attribute_compat_text_section
64 __old_sem_post (sem_t
*sem
)
66 int *futex
= (int *) sem
;
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
);
74 if (__builtin_expect (err
, 0) < 0)
81 compat_symbol (libpthread
, __old_sem_post
, sem_post
, GLIBC_2_0
);