459 lines
15 KiB
C
459 lines
15 KiB
C
/* Copyright (C) 2002-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _DESCR_H
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#define _DESCR_H 1
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#include <limits.h>
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#include <sched.h>
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#include <setjmp.h>
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#include <stdbool.h>
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#include <sys/types.h>
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#include <hp-timing.h>
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#include <list_t.h>
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#include <lowlevellock.h>
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#include <pthreaddef.h>
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#include <dl-sysdep.h>
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#include <thread_db.h>
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#include <tls.h>
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#include <unwind.h>
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#include <bits/types/res_state.h>
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#include <kernel-features.h>
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#include <tls-internal-struct.h>
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#include <sys/rseq.h>
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#ifndef TCB_ALIGNMENT
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# define TCB_ALIGNMENT 32
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#elif TCB_ALIGNMENT < 32
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# error TCB_ALIGNMENT must be at least 32
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#endif
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/* We keep thread specific data in a special data structure, a two-level
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array. The top-level array contains pointers to dynamically allocated
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arrays of a certain number of data pointers. So we can implement a
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sparse array. Each dynamic second-level array has
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PTHREAD_KEY_2NDLEVEL_SIZE
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entries. This value shouldn't be too large. */
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#define PTHREAD_KEY_2NDLEVEL_SIZE 32
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/* We need to address PTHREAD_KEYS_MAX key with PTHREAD_KEY_2NDLEVEL_SIZE
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keys in each subarray. */
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#define PTHREAD_KEY_1STLEVEL_SIZE \
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((PTHREAD_KEYS_MAX + PTHREAD_KEY_2NDLEVEL_SIZE - 1) \
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/ PTHREAD_KEY_2NDLEVEL_SIZE)
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/* Internal version of the buffer to store cancellation handler
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information. */
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struct pthread_unwind_buf
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{
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struct
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{
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__jmp_buf jmp_buf;
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int mask_was_saved;
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} cancel_jmp_buf[1];
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union
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{
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/* This is the placeholder of the public version. */
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void *pad[4];
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struct
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{
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/* Pointer to the previous cleanup buffer. */
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struct pthread_unwind_buf *prev;
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/* Backward compatibility: state of the old-style cleanup
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handler at the time of the previous new-style cleanup handler
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installment. */
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struct _pthread_cleanup_buffer *cleanup;
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/* Cancellation type before the push call. */
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int canceltype;
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} data;
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} priv;
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};
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/* Opcodes and data types for communication with the signal handler to
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change user/group IDs. */
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struct xid_command
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{
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int syscall_no;
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/* Enforce zero-extension for the pointer argument in
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int setgroups (size_t size, const gid_t *list);
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The kernel XID arguments are unsigned and do not require sign
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extension. */
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unsigned long int id[3];
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volatile int cntr;
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volatile int error; /* -1: no call yet, 0: success seen, >0: error seen. */
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};
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/* Data structure used by the kernel to find robust futexes. */
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struct robust_list_head
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{
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void *list;
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long int futex_offset;
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void *list_op_pending;
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};
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/* Data strcture used to handle thread priority protection. */
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struct priority_protection_data
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{
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int priomax;
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unsigned int priomap[];
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};
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#if ! defined __ptr128__
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# define ADJUST_PTR(ptr, op, num) ((uintptr_t) (ptr) op (num))
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#else /* defined __ptr128__ */
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# define ADJUST_PTR(ptr, op, num) \
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({ \
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const char *__ptr = (const char *) (ptr); \
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uintptr_t __num = (uintptr_t) (num); \
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uintptr_t __delta = (uintptr_t) __ptr; \
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__delta = (__delta op __num) - __delta; \
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__ptr + (long) __delta; \
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})
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#endif /* defined __ptr128__ */
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/* Thread descriptor data structure. */
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struct pthread
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{
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union
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{
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#if !TLS_DTV_AT_TP
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/* This overlaps the TCB as used for TLS without threads (see tls.h). */
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tcbhead_t header;
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#else
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struct
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{
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/* multiple_threads is enabled either when the process has spawned at
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least one thread or when a single-threaded process cancels itself.
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This enables additional code to introduce locking before doing some
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compare_and_exchange operations and also enable cancellation points.
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The concepts of multiple threads and cancellation points ideally
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should be separate, since it is not necessary for multiple threads to
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have been created for cancellation points to be enabled, as is the
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case is when single-threaded process cancels itself.
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Since enabling multiple_threads enables additional code in
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cancellation points and compare_and_exchange operations, there is a
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potential for an unneeded performance hit when it is enabled in a
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single-threaded, self-canceling process. This is OK though, since a
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single-threaded process will enable async cancellation only when it
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looks to cancel itself and is hence going to end anyway. */
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int multiple_threads;
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int gscope_flag;
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} header;
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#endif
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/* This extra padding has no special purpose, and this structure layout
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is private and subject to change without affecting the official ABI.
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We just have it here in case it might be convenient for some
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implementation-specific instrumentation hack or suchlike. */
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void *__padding[24];
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};
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/* This descriptor's link on the GL (dl_stack_used) or
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GL (dl_stack_user) list. */
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list_t list;
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/* Thread ID - which is also a 'is this thread descriptor (and
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therefore stack) used' flag. */
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pid_t tid;
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/* Ununsed. */
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pid_t pid_ununsed;
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/* List of robust mutexes the thread is holding. */
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#if __PTHREAD_MUTEX_HAVE_PREV
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void *robust_prev;
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struct robust_list_head robust_head;
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/* The list above is strange. It is basically a double linked list
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but the pointer to the next/previous element of the list points
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in the middle of the object, the __next element. Whenever
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casting to __pthread_list_t we need to adjust the pointer
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first.
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These operations are effectively concurrent code in that the thread
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can get killed at any point in time and the kernel takes over. Thus,
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the __next elements are a kind of concurrent list and we need to
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enforce using compiler barriers that the individual operations happen
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in such a way that the kernel always sees a consistent list. The
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backward links (ie, the __prev elements) are not used by the kernel.
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FIXME We should use relaxed MO atomic operations here and signal fences
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because this kind of concurrency is similar to synchronizing with a
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signal handler. */
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# define QUEUE_PTR_ADJUST (offsetof (__pthread_list_t, __next))
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# define ENQUEUE_MUTEX_BOTH(mutex, val) \
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do { \
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__pthread_list_t *next = (__pthread_list_t *) \
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(ADJUST_PTR (THREAD_GETMEM (THREAD_SELF, robust_head.list), &, ~1ul) \
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- QUEUE_PTR_ADJUST); \
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next->__prev = (void *) &mutex->__data.__list.__next; \
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mutex->__data.__list.__next = THREAD_GETMEM (THREAD_SELF, \
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robust_head.list); \
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mutex->__data.__list.__prev = (void *) &THREAD_SELF->robust_head; \
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/* Ensure that the new list entry is ready before we insert it. */ \
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__asm ("" ::: "memory"); \
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THREAD_SETMEM (THREAD_SELF, robust_head.list, \
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(void *) ADJUST_PTR (&mutex->__data.__list.__next, |, val)); \
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} while (0)
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# define DEQUEUE_MUTEX(mutex) \
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do { \
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__pthread_list_t *next = (__pthread_list_t *) \
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((char *) ADJUST_PTR (mutex->__data.__list.__next, &, ~1ul) \
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- QUEUE_PTR_ADJUST); \
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next->__prev = mutex->__data.__list.__prev; \
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__pthread_list_t *prev = (__pthread_list_t *) \
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((char *) ADJUST_PTR (mutex->__data.__list.__prev, &, ~1ul) \
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- QUEUE_PTR_ADJUST); \
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prev->__next = mutex->__data.__list.__next; \
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/* Ensure that we remove the entry from the list before we change the \
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__next pointer of the entry, which is read by the kernel. */ \
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__asm ("" ::: "memory"); \
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mutex->__data.__list.__prev = NULL; \
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mutex->__data.__list.__next = NULL; \
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} while (0)
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#else
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union
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{
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__pthread_slist_t robust_list;
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struct robust_list_head robust_head;
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};
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# define ENQUEUE_MUTEX_BOTH(mutex, val) \
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do { \
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mutex->__data.__list.__next \
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= THREAD_GETMEM (THREAD_SELF, robust_list.__next); \
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/* Ensure that the new list entry is ready before we insert it. */ \
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__asm ("" ::: "memory"); \
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THREAD_SETMEM (THREAD_SELF, robust_list.__next, \
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(void *) ADJUST_PTR (&mutex->__data.__list, |, val)); \
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} while (0)
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# define DEQUEUE_MUTEX(mutex) \
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do { \
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__pthread_slist_t *runp = (__pthread_slist_t *) \
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ADJUST_PTR (THREAD_GETMEM (THREAD_SELF, robust_list.__next), &, ~1ul); \
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if (runp == &mutex->__data.__list) \
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THREAD_SETMEM (THREAD_SELF, robust_list.__next, runp->__next); \
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else \
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{ \
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__pthread_slist_t *next = (__pthread_slist_t *) \
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ADJUST_PTR (runp->__next, &, ~1ul); \
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while (next != &mutex->__data.__list) \
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{ \
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runp = next; \
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next = (__pthread_slist_t *) ADJUST_PTR(runp->__next, &, ~1ul); \
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} \
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\
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runp->__next = next->__next; \
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/* Ensure that we remove the entry from the list before we change the \
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__next pointer of the entry, which is read by the kernel. */ \
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__asm ("" ::: "memory"); \
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mutex->__data.__list.__next = NULL; \
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} \
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} while (0)
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#endif
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#define ENQUEUE_MUTEX(mutex) ENQUEUE_MUTEX_BOTH (mutex, 0)
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#define ENQUEUE_MUTEX_PI(mutex) ENQUEUE_MUTEX_BOTH (mutex, 1)
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/* List of cleanup buffers. */
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struct _pthread_cleanup_buffer *cleanup;
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/* Unwind information. */
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struct pthread_unwind_buf *cleanup_jmp_buf;
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#define HAVE_CLEANUP_JMP_BUF
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/* Flags determining processing of cancellation. */
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int cancelhandling;
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/* Bit set if cancellation is disabled. */
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#define CANCELSTATE_BIT 0
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#define CANCELSTATE_BITMASK (1 << CANCELSTATE_BIT)
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/* Bit set if asynchronous cancellation mode is selected. */
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#define CANCELTYPE_BIT 1
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#define CANCELTYPE_BITMASK (1 << CANCELTYPE_BIT)
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/* Bit set if canceling has been initiated. */
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#define CANCELING_BIT 2
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#define CANCELING_BITMASK (1 << CANCELING_BIT)
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/* Bit set if canceled. */
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#define CANCELED_BIT 3
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#define CANCELED_BITMASK (1 << CANCELED_BIT)
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/* Bit set if thread is exiting. */
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#define EXITING_BIT 4
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#define EXITING_BITMASK (1 << EXITING_BIT)
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/* Bit set if thread terminated and TCB is freed. */
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#define TERMINATED_BIT 5
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#define TERMINATED_BITMASK (1 << TERMINATED_BIT)
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/* Bit set if thread is supposed to change XID. */
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#define SETXID_BIT 6
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#define SETXID_BITMASK (1 << SETXID_BIT)
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/* Flags. Including those copied from the thread attribute. */
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int flags;
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/* We allocate one block of references here. This should be enough
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to avoid allocating any memory dynamically for most applications. */
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struct pthread_key_data
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{
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/* Sequence number. We use uintptr_t to not require padding on
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32- and 64-bit machines. On 64-bit machines it helps to avoid
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wrapping, too. */
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uintptr_t seq;
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/* Data pointer. */
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void *data;
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} specific_1stblock[PTHREAD_KEY_2NDLEVEL_SIZE];
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/* Two-level array for the thread-specific data. */
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struct pthread_key_data *specific[PTHREAD_KEY_1STLEVEL_SIZE];
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/* Flag which is set when specific data is set. */
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bool specific_used;
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/* True if events must be reported. */
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bool report_events;
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/* True if the user provided the stack. */
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bool user_stack;
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/* True if thread must stop at startup time. */
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bool stopped_start;
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/* Indicate that a thread creation setup has failed (for instance the
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scheduler or affinity). */
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int setup_failed;
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/* Lock to synchronize access to the descriptor. */
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int lock;
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/* Lock for synchronizing setxid calls. */
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unsigned int setxid_futex;
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#if HP_TIMING_INLINE
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hp_timing_t cpuclock_offset_ununsed;
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#endif
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/* If the thread waits to join another one the ID of the latter is
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stored here.
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In case a thread is detached this field contains a pointer of the
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TCB if the thread itself. This is something which cannot happen
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in normal operation. */
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struct pthread *joinid;
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/* Check whether a thread is detached. */
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#define IS_DETACHED(pd) ((pd)->joinid == (pd))
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/* The result of the thread function. */
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void *result;
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/* Scheduling parameters for the new thread. */
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struct sched_param schedparam;
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int schedpolicy;
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/* Start position of the code to be executed and the argument passed
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to the function. */
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void *(*start_routine) (void *);
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void *arg;
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/* Debug state. */
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td_eventbuf_t eventbuf;
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/* Next descriptor with a pending event. */
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struct pthread *nextevent;
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/* Machine-specific unwind info. */
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struct _Unwind_Exception exc;
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/* If nonzero, pointer to the area allocated for the stack and guard. */
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void *stackblock;
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/* Size of the stackblock area including the guard. */
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size_t stackblock_size;
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/* Size of the included guard area. */
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size_t guardsize;
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/* This is what the user specified and what we will report. */
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size_t reported_guardsize;
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/* Thread Priority Protection data. */
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struct priority_protection_data *tpp;
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/* Resolver state. */
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struct __res_state res;
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/* Signal mask for the new thread. Used during thread startup to
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restore the signal mask. (Threads are launched with all signals
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masked.) */
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sigset_t sigmask;
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/* Indicates whether is a C11 thread created by thrd_creat. */
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bool c11;
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/* Used in __pthread_kill_internal to detected a thread that has
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exited or is about to exit. exit_lock must only be acquired
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after blocking signals. */
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bool exiting;
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int exit_lock; /* A low-level lock (for use with __libc_lock_init etc). */
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/* Used on strsignal. */
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struct tls_internal_t tls_state;
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/* rseq area registered with the kernel. */
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struct rseq rseq_area;
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/* This member must be last. */
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char end_padding[];
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#define PTHREAD_STRUCT_END_PADDING \
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(sizeof (struct pthread) - offsetof (struct pthread, end_padding))
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} __attribute ((aligned (TCB_ALIGNMENT)));
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static inline bool
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cancel_enabled_and_canceled (int value)
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{
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return (value & (CANCELSTATE_BITMASK | CANCELED_BITMASK | EXITING_BITMASK
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| TERMINATED_BITMASK))
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== CANCELED_BITMASK;
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}
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static inline bool
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cancel_enabled_and_canceled_and_async (int value)
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{
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return ((value) & (CANCELSTATE_BITMASK | CANCELTYPE_BITMASK | CANCELED_BITMASK
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| EXITING_BITMASK | TERMINATED_BITMASK))
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== (CANCELTYPE_BITMASK | CANCELED_BITMASK);
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}
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/* This yields the pointer that TLS support code calls the thread pointer. */
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#if TLS_TCB_AT_TP
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# define TLS_TPADJ(pd) (pd)
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#elif TLS_DTV_AT_TP
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# define TLS_TPADJ(pd) ((struct pthread *)((char *) (pd) + TLS_PRE_TCB_SIZE))
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#endif
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#endif /* descr.h */
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