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120 lines
3.6 KiB
C
120 lines
3.6 KiB
C
/* Copyright (C) 2002-2014 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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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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#include <errno.h>
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#include <stdlib.h>
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#include <atomic.h>
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#include "pthreadP.h"
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#include <stap-probe.h>
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static void
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cleanup (void *arg)
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{
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/* If we already changed the waiter ID, reset it. The call cannot
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fail for any reason but the thread not having done that yet so
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there is no reason for a loop. */
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(void) atomic_compare_and_exchange_bool_acq ((struct pthread **) arg, NULL,
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THREAD_SELF);
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}
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int
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pthread_join (threadid, thread_return)
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pthread_t threadid;
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void **thread_return;
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{
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struct pthread *pd = (struct pthread *) threadid;
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/* Make sure the descriptor is valid. */
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if (INVALID_NOT_TERMINATED_TD_P (pd))
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/* Not a valid thread handle. */
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return ESRCH;
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/* Is the thread joinable?. */
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if (IS_DETACHED (pd))
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/* We cannot wait for the thread. */
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return EINVAL;
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struct pthread *self = THREAD_SELF;
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int result = 0;
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LIBC_PROBE (pthread_join, 1, threadid);
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/* During the wait we change to asynchronous cancellation. If we
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are canceled the thread we are waiting for must be marked as
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un-wait-ed for again. */
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pthread_cleanup_push (cleanup, &pd->joinid);
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/* Switch to asynchronous cancellation. */
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int oldtype = CANCEL_ASYNC ();
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if ((pd == self
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|| (self->joinid == pd
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&& (pd->cancelhandling
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& (CANCELING_BITMASK | CANCELED_BITMASK | EXITING_BITMASK
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| TERMINATED_BITMASK)) == 0))
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&& !CANCEL_ENABLED_AND_CANCELED (self->cancelhandling))
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/* This is a deadlock situation. The threads are waiting for each
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other to finish. Note that this is a "may" error. To be 100%
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sure we catch this error we would have to lock the data
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structures but it is not necessary. In the unlikely case that
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two threads are really caught in this situation they will
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deadlock. It is the programmer's problem to figure this
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out. */
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result = EDEADLK;
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/* Wait for the thread to finish. If it is already locked something
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is wrong. There can only be one waiter. */
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else if (__builtin_expect (atomic_compare_and_exchange_bool_acq (&pd->joinid,
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self,
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NULL), 0))
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/* There is already somebody waiting for the thread. */
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result = EINVAL;
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else
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/* Wait for the child. */
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lll_wait_tid (pd->tid);
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/* Restore cancellation mode. */
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CANCEL_RESET (oldtype);
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/* Remove the handler. */
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pthread_cleanup_pop (0);
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if (__builtin_expect (result == 0, 1))
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{
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/* We mark the thread as terminated and as joined. */
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pd->tid = -1;
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/* Store the return value if the caller is interested. */
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if (thread_return != NULL)
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*thread_return = pd->result;
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/* Free the TCB. */
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__free_tcb (pd);
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}
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LIBC_PROBE (pthread_join_ret, 3, threadid, result, pd->result);
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return result;
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}
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