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glibc  2.9
pthread_join.c File Reference
#include <errno.h>
#include <stdlib.h>
#include <atomic.h>
#include "pthreadP.h"

Go to the source code of this file.


static void cleanup (void *arg)
int pthread_join (pthread_t threadid, void **thread_return)

Function Documentation

static void cleanup ( void *  arg) [static]

Definition at line 28 of file pthread_join.c.

  /* If we already changed the waiter ID, reset it.  The call cannot
     fail for any reason but the thread not having done that yet so
     there is no reason for a loop.  */
  (void) atomic_compare_and_exchange_bool_acq ((struct pthread **) arg, NULL,
int pthread_join ( pthread_t  threadid,
void **  thread_return 

Definition at line 39 of file pthread_join.c.

  struct pthread *pd = (struct pthread *) threadid;

  /* Make sure the descriptor is valid.  */
    /* Not a valid thread handle.  */
    return ESRCH;

  /* Is the thread joinable?.  */
  if (IS_DETACHED (pd))
    /* We cannot wait for the thread.  */
    return EINVAL;

  struct pthread *self = THREAD_SELF;
  int result = 0;

  /* During the wait we change to asynchronous cancellation.  If we
     are canceled the thread we are waiting for must be marked as
     un-wait-ed for again.  */
  pthread_cleanup_push (cleanup, &pd->joinid);

  /* Switch to asynchronous cancellation.  */
  int oldtype = CANCEL_ASYNC ();

  if ((pd == self
       || (self->joinid == pd
          && (pd->cancelhandling
                | TERMINATED_BITMASK)) == 0))
      && !CANCEL_ENABLED_AND_CANCELED (self->cancelhandling))
    /* This is a deadlock situation.  The threads are waiting for each
       other to finish.  Note that this is a "may" error.  To be 100%
       sure we catch this error we would have to lock the data
       structures but it is not necessary.  In the unlikely case that
       two threads are really caught in this situation they will
       deadlock.  It is the programmer's problem to figure this
       out.  */
    result = EDEADLK;
  /* Wait for the thread to finish.  If it is already locked something
     is wrong.  There can only be one waiter.  */
  else if (__builtin_expect (atomic_compare_and_exchange_bool_acq (&pd->joinid,
                                                           NULL), 0))
    /* There is already somebody waiting for the thread.  */
    result = EINVAL;
    /* Wait for the child.  */
    lll_wait_tid (pd->tid);

  /* Restore cancellation mode.  */
  CANCEL_RESET (oldtype);

  /* Remove the handler.  */
  pthread_cleanup_pop (0);

  if (__builtin_expect (result == 0, 1))
      /* We mark the thread as terminated and as joined.  */
      pd->tid = -1;

      /* Store the return value if the caller is interested.  */
      if (thread_return != NULL)
       *thread_return = pd->result;

      /* Free the TCB.  */
      __free_tcb (pd);

  return result;

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