1 /* Copyright (C) 2003-2013 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
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 <http://www.gnu.org/licenses/>. */
22 #include <lowlevellock.h>
26 #include <shlib-compat.h>
27 #include <kernel-features.h>
28 #include <stap-probe.h>
32 __pthread_cond_signal (cond)
35 int pshared = (cond->__data.__mutex == (void *) ~0l)
36 ? LLL_SHARED : LLL_PRIVATE;
38 LIBC_PROBE (cond_signal, 1, cond);
40 /* Make sure we are alone. */
41 lll_lock (cond->__data.__lock, pshared);
43 /* Are there any waiters to be woken? */
44 if (cond->__data.__total_seq > cond->__data.__wakeup_seq)
46 /* Yes. Mark one of them as woken. */
47 ++cond->__data.__wakeup_seq;
48 ++cond->__data.__futex;
50 #if (defined lll_futex_cmp_requeue_pi \
51 && defined __ASSUME_REQUEUE_PI)
52 int pi_flag = PTHREAD_MUTEX_PRIO_INHERIT_NP | PTHREAD_MUTEX_ROBUST_NP;
53 pthread_mutex_t *mut = cond->__data.__mutex;
55 /* Do not use requeue for pshared condvars. */
56 if (mut != (void *) ~0l)
57 pi_flag &= mut->__data.__kind;
59 if (__builtin_expect (pi_flag == PTHREAD_MUTEX_PRIO_INHERIT_NP, 0)
60 /* This can only really fail with a ENOSYS, since nobody can modify
61 futex while we have the cond_lock. */
62 && lll_futex_cmp_requeue_pi (&cond->__data.__futex, 1, 0,
64 cond->__data.__futex, pshared) == 0)
66 lll_unlock (cond->__data.__lock, pshared);
72 if (! __builtin_expect (lll_futex_wake_unlock (&cond->__data.__futex,
78 /* Fallback if neither of them work. */
79 lll_futex_wake (&cond->__data.__futex, 1, pshared);
83 lll_unlock (cond->__data.__lock, pshared);
88 versioned_symbol (libpthread, __pthread_cond_signal, pthread_cond_signal,