summaryrefslogtreecommitdiff
path: root/aarch64-none-linux-gnu/libc/usr/include/bits/struct_mutex.h
diff options
context:
space:
mode:
Diffstat (limited to 'aarch64-none-linux-gnu/libc/usr/include/bits/struct_mutex.h')
-rw-r--r--aarch64-none-linux-gnu/libc/usr/include/bits/struct_mutex.h84
1 files changed, 84 insertions, 0 deletions
diff --git a/aarch64-none-linux-gnu/libc/usr/include/bits/struct_mutex.h b/aarch64-none-linux-gnu/libc/usr/include/bits/struct_mutex.h
new file mode 100644
index 0000000..322e8aa
--- /dev/null
+++ b/aarch64-none-linux-gnu/libc/usr/include/bits/struct_mutex.h
@@ -0,0 +1,84 @@
+/* Default mutex implementation struct definitions.
+ Copyright (C) 2019-2023 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 _THREAD_MUTEX_INTERNAL_H
+#define _THREAD_MUTEX_INTERNAL_H 1
+
+/* Generic struct for both POSIX and C11 mutexes. New ports are expected
+ to use the default layout, however architecture can redefine it to
+ add arch-specific extension (such as lock-elision). The struct have
+ a size of 32 bytes on LP32 and 40 bytes on LP64 architectures. */
+
+struct __pthread_mutex_s
+{
+ int __lock __LOCK_ALIGNMENT;
+ unsigned int __count;
+ int __owner;
+#if __WORDSIZE == 64
+ unsigned int __nusers;
+#endif
+ /* KIND must stay at this position in the structure to maintain
+ binary compatibility with static initializers.
+
+ Concurrency notes:
+ The __kind of a mutex is initialized either by the static
+ PTHREAD_MUTEX_INITIALIZER or by a call to pthread_mutex_init.
+
+ After a mutex has been initialized, the __kind of a mutex is usually not
+ changed. BUT it can be set to -1 in pthread_mutex_destroy or elision can
+ be enabled. This is done concurrently in the pthread_mutex_*lock
+ functions by using the macro FORCE_ELISION. This macro is only defined
+ for architectures which supports lock elision.
+
+ For elision, there are the flags PTHREAD_MUTEX_ELISION_NP and
+ PTHREAD_MUTEX_NO_ELISION_NP which can be set in addition to the already
+ set type of a mutex. Before a mutex is initialized, only
+ PTHREAD_MUTEX_NO_ELISION_NP can be set with pthread_mutexattr_settype.
+
+ After a mutex has been initialized, the functions pthread_mutex_*lock can
+ enable elision - if the mutex-type and the machine supports it - by
+ setting the flag PTHREAD_MUTEX_ELISION_NP. This is done concurrently.
+ Afterwards the lock / unlock functions are using specific elision
+ code-paths. */
+ int __kind;
+#if __WORDSIZE != 64
+ unsigned int __nusers;
+#endif
+#if __WORDSIZE == 64
+ int __spins;
+ __pthread_list_t __list;
+# define __PTHREAD_MUTEX_HAVE_PREV 1
+#else
+ __extension__ union
+ {
+ int __spins;
+ __pthread_slist_t __list;
+ };
+# define __PTHREAD_MUTEX_HAVE_PREV 0
+#endif
+};
+
+#if __PTHREAD_MUTEX_HAVE_PREV == 1
+# define __PTHREAD_MUTEX_INITIALIZER(__kind) \
+ 0, 0, 0, 0, __kind, 0, { 0, 0 }
+#else
+# define __PTHREAD_MUTEX_INITIALIZER(__kind) \
+ 0, 0, 0, __kind, 0, { 0 }
+#endif
+
+#endif