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git.ipfire.org Git - thirdparty/glibc.git/blob - sysdeps/htl/sem-post.c
1 /* Post a semaphore. Generic version.
2 Copyright (C) 2005-2019 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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.
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.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
19 #include <semaphore.h>
22 #include <pt-internal.h>
25 __sem_post (sem_t
*sem
)
27 struct __pthread
*wakeup
;
29 __pthread_spin_lock (&sem
->__lock
);
33 assert (sem
->__queue
== NULL
);
35 __pthread_spin_unlock (&sem
->__lock
);
39 if (sem
->__queue
== NULL
)
43 __pthread_spin_unlock (&sem
->__lock
);
47 /* Wake someone up. */
49 /* First dequeue someone. */
50 wakeup
= sem
->__queue
;
51 __pthread_dequeue (wakeup
);
53 /* Then drop the lock and transfer control. */
54 __pthread_spin_unlock (&sem
->__lock
);
56 __pthread_wakeup (wakeup
);
61 strong_alias (__sem_post
, sem_post
);