f8bf15febc
The commit documents the ownership rules around 'struct pthread' and when a thread can read or write to the descriptor. With those ownership rules in place it becomes obvious that pd->stopped_start should not be touched in several of the paths during thread startup, particularly so for detached threads. In the case of detached threads, between the time the thread is created by the OS kernel and the creating thread checks pd->stopped_start, the detached thread might have already exited and the memory for pd unmapped. As a regression test we add a simple test which exercises this exact case by quickly creating detached threads with large enough stacks to ensure the thread stack cache is bypassed and the stacks are unmapped. Before the fix the testcase segfaults, after the fix it works correctly and completes without issue. For a detailed discussion see: https://www.sourceware.org/ml/libc-alpha/2017-01/msg00505.html
78 lines
3.3 KiB
C
78 lines
3.3 KiB
C
/* Support functionality for using threads.
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Copyright (C) 2016-2017 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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<http://www.gnu.org/licenses/>. */
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#ifndef SUPPORT_THREAD_H
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#define SUPPORT_THREAD_H
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#include <pthread.h>
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#include <sys/cdefs.h>
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__BEGIN_DECLS
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/* Terminate the process (with exit status 0) after SECONDS have
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elapsed, from a helper thread. The process is terminated with the
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exit function, so atexit handlers are executed. */
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void delayed_exit (int seconds);
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/* Terminate the process (with exit status 1) if VALUE is not zero.
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In that case, print a failure message to standard output mentioning
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FUNCTION. The process is terminated with the exit function, so
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atexit handlers are executed. */
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void xpthread_check_return (const char *function, int value);
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/* The following functions call the corresponding libpthread functions
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and terminate the process on error. */
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void xpthread_barrier_init (pthread_barrier_t *barrier,
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pthread_barrierattr_t *attr, unsigned int count);
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void xpthread_barrier_destroy (pthread_barrier_t *barrier);
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void xpthread_mutexattr_destroy (pthread_mutexattr_t *);
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void xpthread_mutexattr_init (pthread_mutexattr_t *);
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void xpthread_mutexattr_setprotocol (pthread_mutexattr_t *, int);
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void xpthread_mutexattr_setpshared (pthread_mutexattr_t *, int);
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void xpthread_mutexattr_setrobust (pthread_mutexattr_t *, int);
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void xpthread_mutexattr_settype (pthread_mutexattr_t *, int);
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void xpthread_mutex_init (pthread_mutex_t *, const pthread_mutexattr_t *);
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void xpthread_mutex_destroy (pthread_mutex_t *);
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void xpthread_mutex_lock (pthread_mutex_t *mutex);
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void xpthread_mutex_unlock (pthread_mutex_t *mutex);
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void xpthread_mutex_consistent (pthread_mutex_t *);
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void xpthread_spin_lock (pthread_spinlock_t *lock);
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void xpthread_spin_unlock (pthread_spinlock_t *lock);
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void xpthread_cond_wait (pthread_cond_t * cond, pthread_mutex_t * mutex);
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pthread_t xpthread_create (pthread_attr_t *attr,
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void *(*thread_func) (void *), void *closure);
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void xpthread_detach (pthread_t thr);
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void xpthread_cancel (pthread_t thr);
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void *xpthread_join (pthread_t thr);
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void xpthread_once (pthread_once_t *guard, void (*func) (void));
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void xpthread_attr_destroy (pthread_attr_t *attr);
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void xpthread_attr_init (pthread_attr_t *attr);
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void xpthread_attr_setdetachstate (pthread_attr_t *attr,
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int detachstate);
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void xpthread_attr_setstacksize (pthread_attr_t *attr,
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size_t stacksize);
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/* This function returns non-zero if pthread_barrier_wait returned
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PTHREAD_BARRIER_SERIAL_THREAD. */
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int xpthread_barrier_wait (pthread_barrier_t *barrier);
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__END_DECLS
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#endif /* SUPPORT_THREAD_H */
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