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authorAdhemerval Zanella <adhemerval.zanella@linaro.org>2017-06-27 10:29:29 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2018-07-24 14:06:45 -0300
commitce7528f637f7b9cddb3c22081d7e09b2a26c89bf (patch)
tree96263946f49c1ac25f61ee9aeebd3b0e34fd5036 /nptl
parente27f41ba2b6101be1a511905bff5502ffd23828b (diff)
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nptl: Add C11 threads thrd_* functions
This patch adds the thrd_* definitions from C11 threads (ISO/IEC 9899:2011), more specifically thrd_create, thrd_curent, rhd_detach, thrd_equal, thrd_exit, thrd_join, thrd_sleep, thrd_yield, and required types. Mostly of the definitions are composed based on POSIX conterparts, such as thrd_t (using pthread_t). For thrd_* function internally direct POSIX pthread call are used with the exceptions: 1. thrd_start uses pthread_create internal implementation, but changes how to actually calls the start routine. This is due the difference in signature between POSIX and C11, where former return a 'void *' and latter 'int'. To avoid calling convention issues due 'void *' to int cast, routines from C11 threads are started slight different than default pthread one. Explicit cast to expected return are used internally on pthread_create and the result is stored back to void also with an explicit cast. 2. thrd_sleep uses nanosleep internal direct syscall to avoid clobbering errno and to handle expected standard return codes. It is a cancellation entrypoint to be consistent with both thrd_join and cnd_{timed}wait. 3. thrd_yield also uses internal direct syscall to avoid errno clobbering. Checked with a build for all major ABI (aarch64-linux-gnu, alpha-linux-gnu, arm-linux-gnueabi, i386-linux-gnu, ia64-linux-gnu, m68k-linux-gnu, microblaze-linux-gnu [1], mips{64}-linux-gnu, nios2-linux-gnu, powerpc{64le}-linux-gnu, s390{x}-linux-gnu, sparc{64}-linux-gnu, and x86_64-linux-gnu). Also ran a full check on aarch64-linux-gnu, x86_64-linux-gnu, i686-linux-gnu, arm-linux-gnueabhf, and powerpc64le-linux-gnu. [BZ #14092] * conform/Makefile (conformtest-headers-ISO11): Add threads.h. (linknamespace-libs-ISO11): Add libpthread.a. * conform/data/threads.h-data: New file: add C11 thrd_* types and functions. * include/stdc-predef.h (__STDC_NO_THREADS__): Remove definition. * nptl/Makefile (headers): Add threads.h. (libpthread-routines): Add new C11 thread thrd_create, thrd_current, thrd_detach, thrd_equal, thrd_exit, thrd_join, thrd_sleep, and thrd_yield. * nptl/Versions (libpthread) [GLIBC_2.28]): Add new C11 thread thrd_create, thrd_current, thrd_detach, thrd_equal, thrd_exit, thrd_join, thrd_sleep, and thrd_yield symbols. * nptl/descr.h (struct pthread): Add c11 field. * nptl/pthreadP.h (ATTR_C11_THREAD): New define. * nptl/pthread_create.c (START_THREAD_DEFN): Call C11 thread start routine with expected function prototype. (__pthread_create_2_1): Add C11 threads check based on attribute value. * sysdeps/unix/sysdep.h (INTERNAL_SYSCALL_CANCEL): New macro. * nptl/thrd_create.c: New file. * nptl/thrd_current.c: Likewise. * nptl/thrd_detach.c: Likewise. * nptl/thrd_equal.c: Likewise. * nptl/thrd_exit.c: Likewise. * nptl/thrd_join.c: Likewise. * nptl/thrd_priv.h: Likewise. * nptl/thrd_sleep.c: Likewise. * nptl/thrd_yield.c: Likewise. * include/threads.h: Likewise.
Diffstat (limited to 'nptl')
-rw-r--r--nptl/Makefile8
-rw-r--r--nptl/Versions9
-rw-r--r--nptl/descr.h3
-rw-r--r--nptl/pthreadP.h3
-rw-r--r--nptl/pthread_create.c18
-rw-r--r--nptl/thrd_create.c30
-rw-r--r--nptl/thrd_current.c25
-rw-r--r--nptl/thrd_detach.c28
-rw-r--r--nptl/thrd_equal.c25
-rw-r--r--nptl/thrd_exit.c25
-rw-r--r--nptl/thrd_join.c30
-rw-r--r--nptl/thrd_priv.h45
-rw-r--r--nptl/thrd_sleep.c39
-rw-r--r--nptl/thrd_yield.c26
-rw-r--r--nptl/threads.h90
15 files changed, 399 insertions, 5 deletions
diff --git a/nptl/Makefile b/nptl/Makefile
index 2f2bb05..1fcf29f 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -22,14 +22,15 @@ subdir := nptl
include ../Makeconfig
-headers := pthread.h semaphore.h bits/semaphore.h
+headers := pthread.h semaphore.h bits/semaphore.h threads.h
extra-libs := libpthread
extra-libs-others := $(extra-libs)
routines = alloca_cutoff forward libc-lowlevellock libc-cancellation \
libc-cleanup libc_pthread_init libc_multiple_threads \
- register-atfork pthread_atfork pthread_self
+ register-atfork pthread_atfork pthread_self thrd_current \
+ thrd_equal thrd_sleep thrd_yield
shared-only-routines = forward
static-only-routines = pthread_atfork
@@ -139,7 +140,8 @@ libpthread-routines = nptl-init nptlfreeres vars events version pt-interp \
pthread_mutex_getprioceiling \
pthread_mutex_setprioceiling \
pthread_setname pthread_getname \
- pthread_setattr_default_np pthread_getattr_default_np
+ pthread_setattr_default_np pthread_getattr_default_np \
+ thrd_create thrd_detach thrd_exit thrd_join
# pthread_setuid pthread_seteuid pthread_setreuid \
# pthread_setresuid \
# pthread_setgid pthread_setegid pthread_setregid \
diff --git a/nptl/Versions b/nptl/Versions
index b1c2da0..38d7e48 100644
--- a/nptl/Versions
+++ b/nptl/Versions
@@ -28,6 +28,10 @@ libc {
pthread_cond_wait; pthread_cond_signal;
pthread_cond_broadcast; pthread_cond_timedwait;
}
+ # C11 thread symbols.
+ GLIBC_2.28 {
+ thrd_current; thrd_equal; thrd_sleep; thrd_yield;
+ }
GLIBC_PRIVATE {
__libc_alloca_cutoff;
# Internal libc interface to libpthread
@@ -265,6 +269,11 @@ libpthread {
GLIBC_2.22 {
}
+ # C11 thread symbols.
+ GLIBC_2.28 {
+ thrd_create; thrd_detach; thrd_exit; thrd_join;
+ }
+
GLIBC_PRIVATE {
__pthread_initialize_minimal;
__pthread_clock_gettime; __pthread_clock_settime;
diff --git a/nptl/descr.h b/nptl/descr.h
index 0a0abb4..9c01e1b 100644
--- a/nptl/descr.h
+++ b/nptl/descr.h
@@ -392,6 +392,9 @@ struct pthread
/* Resolver state. */
struct __res_state res;
+ /* Indicates whether is a C11 thread created by thrd_creat. */
+ bool c11;
+
/* This member must be last. */
char end_padding[];
diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h
index 3cba0b6..13bdb11 100644
--- a/nptl/pthreadP.h
+++ b/nptl/pthreadP.h
@@ -173,6 +173,9 @@ enum
#define __PTHREAD_ONCE_DONE 2
#define __PTHREAD_ONCE_FORK_GEN_INCR 4
+/* Attribute to indicate thread creation was issued from C11 thrd_create. */
+#define ATTR_C11_THREAD ((void*)(uintptr_t)-1)
+
/* Condition variable definitions. See __pthread_cond_wait_common.
Need to be defined here so there is one place from which
diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index 5f5a007..fe75d04 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -472,7 +472,19 @@ START_THREAD_DEFN
LIBC_PROBE (pthread_start, 3, (pthread_t) pd, pd->start_routine, pd->arg);
/* Run the code the user provided. */
- THREAD_SETMEM (pd, result, pd->start_routine (pd->arg));
+ void *ret;
+ if (pd->c11)
+ {
+ /* The function pointer of the c11 thread start is cast to an incorrect
+ type on __pthread_create_2_1 call, however it is casted back to correct
+ one so the call behavior is well-defined (it is assumed that pointers
+ to void are able to represent all values of int. */
+ int (*start)(void*) = (int (*) (void*)) pd->start_routine;
+ ret = (void*) (uintptr_t) start (pd->arg);
+ }
+ else
+ ret = pd->start_routine (pd->arg);
+ THREAD_SETMEM (pd, result, ret);
}
/* Call destructors for the thread_local TLS variables. */
@@ -625,7 +637,8 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
const struct pthread_attr *iattr = (struct pthread_attr *) attr;
struct pthread_attr default_attr;
bool free_cpuset = false;
- if (iattr == NULL)
+ bool c11 = (attr == ATTR_C11_THREAD);
+ if (iattr == NULL || c11)
{
lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
default_attr = __default_pthread_attr;
@@ -683,6 +696,7 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
get the information from its thread descriptor. */
pd->start_routine = start_routine;
pd->arg = arg;
+ pd->c11 = c11;
/* Copy the thread attribute flags. */
struct pthread *self = THREAD_SELF;
diff --git a/nptl/thrd_create.c b/nptl/thrd_create.c
new file mode 100644
index 0000000..113ba0d
--- /dev/null
+++ b/nptl/thrd_create.c
@@ -0,0 +1,30 @@
+/* C11 threads thread creation implementation.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include "thrd_priv.h"
+
+int
+thrd_create (thrd_t *thr, thrd_start_t func, void *arg)
+{
+ _Static_assert (sizeof (thr) == sizeof (pthread_t),
+ "sizeof (thr) != sizeof (pthread_t)");
+
+ int err_code = __pthread_create_2_1 (thr, ATTR_C11_THREAD,
+ (void* (*) (void*))func, arg);
+ return thrd_err_map (err_code);
+}
diff --git a/nptl/thrd_current.c b/nptl/thrd_current.c
new file mode 100644
index 0000000..a1c73b2
--- /dev/null
+++ b/nptl/thrd_current.c
@@ -0,0 +1,25 @@
+/* C11 threads current thread implementation.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include "thrd_priv.h"
+
+thrd_t
+thrd_current (void)
+{
+ return (thrd_t) THREAD_SELF;
+}
diff --git a/nptl/thrd_detach.c b/nptl/thrd_detach.c
new file mode 100644
index 0000000..be2c3e1
--- /dev/null
+++ b/nptl/thrd_detach.c
@@ -0,0 +1,28 @@
+/* C11 threads thread detach implementation.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include "thrd_priv.h"
+
+int
+thrd_detach (thrd_t thr)
+{
+ int err_code;
+
+ err_code = __pthread_detach (thr);
+ return thrd_err_map (err_code);
+}
diff --git a/nptl/thrd_equal.c b/nptl/thrd_equal.c
new file mode 100644
index 0000000..8e13bc4
--- /dev/null
+++ b/nptl/thrd_equal.c
@@ -0,0 +1,25 @@
+/* C11 threads thread equality check implementation.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include "thrd_priv.h"
+
+int
+thrd_equal (thrd_t lhs, thrd_t rhs)
+{
+ return lhs == rhs;
+}
diff --git a/nptl/thrd_exit.c b/nptl/thrd_exit.c
new file mode 100644
index 0000000..6b37774
--- /dev/null
+++ b/nptl/thrd_exit.c
@@ -0,0 +1,25 @@
+/* C11 threads thread exit implementation.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include "thrd_priv.h"
+
+_Noreturn void
+thrd_exit (int res)
+{
+ __pthread_exit ((void*)(uintptr_t) res);
+}
diff --git a/nptl/thrd_join.c b/nptl/thrd_join.c
new file mode 100644
index 0000000..029d4a7
--- /dev/null
+++ b/nptl/thrd_join.c
@@ -0,0 +1,30 @@
+/* C11 threads thread join implementation.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include "thrd_priv.h"
+
+int
+thrd_join (thrd_t thr, int *res)
+{
+ void *pthread_res;
+ int err_code = __pthread_timedjoin_ex (thr, &pthread_res, NULL, true);
+ if (res)
+ *res = (int) (uintptr_t) pthread_res;
+
+ return thrd_err_map (err_code);
+}
diff --git a/nptl/thrd_priv.h b/nptl/thrd_priv.h
new file mode 100644
index 0000000..97f4102
--- /dev/null
+++ b/nptl/thrd_priv.h
@@ -0,0 +1,45 @@
+/* Internal C11 threads definitions.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifndef THRD_PRIV_H
+# define THRD_PRIV_H
+
+#include <features.h>
+#include <threads.h>
+#include <errno.h>
+#include "pthreadP.h" /* For pthread_{mutex,cond}_t definitions. */
+
+static __always_inline int
+thrd_err_map (int err_code)
+{
+ switch (err_code)
+ {
+ case 0:
+ return thrd_success;
+ case ENOMEM:
+ return thrd_nomem;
+ case ETIMEDOUT:
+ return thrd_timedout;
+ case EBUSY:
+ return thrd_busy;
+ default:
+ return thrd_error;
+ }
+}
+
+#endif
diff --git a/nptl/thrd_sleep.c b/nptl/thrd_sleep.c
new file mode 100644
index 0000000..85736ed
--- /dev/null
+++ b/nptl/thrd_sleep.c
@@ -0,0 +1,39 @@
+/* C11 threads thread sleep implementation.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <time.h>
+#include <sysdep-cancel.h>
+
+#include "thrd_priv.h"
+
+int
+thrd_sleep (const struct timespec* time_point, struct timespec* remaining)
+{
+ INTERNAL_SYSCALL_DECL (err);
+ int ret = INTERNAL_SYSCALL_CANCEL (nanosleep, err, time_point, remaining);
+ if (INTERNAL_SYSCALL_ERROR_P (ret, err))
+ {
+ /* C11 states thrd_sleep function returns -1 if it has been interrupted
+ by a signal, or a negative value if it fails. */
+ ret = INTERNAL_SYSCALL_ERRNO (ret, err);
+ if (ret == EINTR)
+ return -1;
+ return -2;
+ }
+ return 0;
+}
diff --git a/nptl/thrd_yield.c b/nptl/thrd_yield.c
new file mode 100644
index 0000000..9ebcbae
--- /dev/null
+++ b/nptl/thrd_yield.c
@@ -0,0 +1,26 @@
+/* C11 threads thread yield implementation.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include "thrd_priv.h"
+
+void
+thrd_yield (void)
+{
+ INTERNAL_SYSCALL_DECL (err);
+ INTERNAL_SYSCALL_CALL (sched_yield, err);
+}
diff --git a/nptl/threads.h b/nptl/threads.h
new file mode 100644
index 0000000..5258e23
--- /dev/null
+++ b/nptl/threads.h
@@ -0,0 +1,90 @@
+/* ISO C11 Standard: 7.26 - Thread support library <threads.h>.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifndef _THREADS_H
+#define _THREADS_H 1
+
+#include <features.h>
+#include <time.h>
+
+__BEGIN_DECLS
+
+#include <bits/types/struct_timespec.h>
+
+typedef unsigned long int thrd_t;
+typedef int (*thrd_start_t) (void*);
+
+/* Exit and error codes. */
+enum
+{
+ thrd_success = 0,
+ thrd_busy = 1,
+ thrd_error = 2,
+ thrd_nomem = 3,
+ thrd_timedout = 4
+};
+
+/* Threads functions. */
+
+/* Create a new thread executing the function __FUNC. Arguments for __FUNC
+ are passed through __ARG. If succesful, __THR is set to new thread
+ identifier. */
+extern int thrd_create (thrd_t *__thr, thrd_start_t __func, void *__arg);
+
+/* Check if __LHS and __RHS point to the same thread. */
+extern int thrd_equal (thrd_t __lhs, thrd_t __rhs);
+
+/* Return current thread identifier. */
+extern thrd_t thrd_current (void);
+
+/* Block current thread execution for at least the time pointed by
+ __TIME_POINT. The current thread may resume if receives a signal. In
+ that case, if __REMAINING is not NULL, the remaining time is stored in
+ the object pointed by it. */
+extern int thrd_sleep (const struct timespec *__time_point,
+ struct timespec *__remaining);
+
+/* Terminate current thread execution, cleaning up any thread local
+ storage and freeing resources. Returns the value specified in __RES. */
+extern void thrd_exit (int __res) __attribute__ ((__noreturn__));
+
+/* Detach the thread identified by __THR from the current environment
+ (it does not allow join or wait for it). */
+extern int thrd_detach (thrd_t __thr);
+
+/* Block current thread until execution of __THR is complete. In case that
+ __RES is not NULL, will store the return value of __THR when exiting. */
+extern int thrd_join (thrd_t __thr, int *__res);
+
+/* Stop current thread execution and call the scheduler to decide which
+ thread should execute next. The current thread may be selected by the
+ scheduler to keep running. */
+extern void thrd_yield (void);
+
+#ifdef __USE_EXTERN_INLINES
+/* Optimizations. */
+__extern_inline int
+thrd_equal (thrd_t __thread1, thrd_t __thread2)
+{
+ return __thread1 == __thread2;
+}
+#endif
+
+__END_DECLS
+
+#endif /* _THREADS_H */