text: /* Copyright (C) 2003-2012 Free Software Foundation, Inc.
     This file is part of the GNU C Library.
     Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
  
     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/>.  */
  
  #include <endian.h>
  #include <errno.h>
  #include <sysdep.h>
  #include <lowlevellock.h>
  #include <pthread.h>
  #include <pthreadP.h>
  
  #include <shlib-compat.h>
  #include <stap-probe.h>
  
  
  struct _condvar_cleanup_buffer
  {
    int oldtype;
    pthread_cond_t *cond;
    pthread_mutex_t *mutex;
    unsigned int bc_seq;
  };
  
  
  void
  __attribute__ ((visibility ("hidden")))
  __condvar_cleanup (void *arg)
  {
    struct _condvar_cleanup_buffer *cbuffer =
      (struct _condvar_cleanup_buffer *) arg;
    unsigned int destroying;
    int pshared = (cbuffer->cond->__data.__mutex == (void *) ~0l)
  		? LLL_SHARED : LLL_PRIVATE;
  
    /* We are going to modify shared data.  */
    lll_lock (cbuffer->cond->__data.__lock, pshared);
  
    if (cbuffer->bc_seq == cbuffer->cond->__data.__broadcast_seq)
      {
        /* This thread is not waiting anymore.  Adjust the sequence counters
  	 appropriately.  We do not increment WAKEUP_SEQ if this would
  	 bump it over the value of TOTAL_SEQ.  This can happen if a thread
  	 was woken and then canceled.  */
        if (cbuffer->cond->__data.__wakeup_seq
  	  < cbuffer->cond->__data.__total_seq)
  	{
  	  ++cbuffer->cond->__data.__wakeup_seq;
  	  ++cbuffer->cond->__data.__futex;
  	}
        ++cbuffer->cond->__data.__woken_seq;
      }
  
    cbuffer->cond->__data.__nwaiters -= 1 << COND_NWAITERS_SHIFT;
  
    /* If pthread_cond_destroy was called on this variable already,
       notify the pthread_cond_destroy caller all waiters have left
       and it can be successfully destroyed.  */
    destroying = 0;
    if (cbuffer->cond->__data.__total_seq == -1ULL
        && cbuffer->cond->__data.__nwaiters < (1 << COND_NWAITERS_SHIFT))
      {
        lll_futex_wake (&cbuffer->cond->__data.__nwaiters, 1, pshared);
        destroying = 1;
      }
  
    /* We are done.  */
    lll_unlock (cbuffer->cond->__data.__lock, pshared);
  
    /* Wake everybody to make sure no condvar signal gets lost.  */
    if (! destroying)
      lll_futex_wake (&cbuffer->cond->__data.__futex, INT_MAX, pshared);
  
    /* Get the mutex before returning unless asynchronous cancellation
       is in effect.  */
    __pthread_mutex_cond_lock (cbuffer->mutex);
  }
  
  
  int
  __pthread_cond_wait (cond, mutex)
       pthread_cond_t *cond;
       pthread_mutex_t *mutex;
  {
    struct _pthread_cleanup_buffer buffer;
    struct _condvar_cleanup_buffer cbuffer;
    int err;
    int pshared = (cond->__data.__mutex == (void *) ~0l)
  		? LLL_SHARED : LLL_PRIVATE;
  
    LIBC_PROBE (cond_wait, 2, cond, mutex);
  
    /* Make sure we are alone.  */
    lll_lock (cond->__data.__lock, pshared);
  
    /* Now we can release the mutex.  */
    err = __pthread_mutex_unlock_usercnt (mutex, 0);
    if (__builtin_expect (err, 0))
      {
        lll_unlock (cond->__data.__lock, pshared);
        return err;
      }
  
    /* We have one new user of the condvar.  */
    ++cond->__data.__total_seq;
    ++cond->__data.__futex;
    cond->__data.__nwaiters += 1 << COND_NWAITERS_SHIFT;
  
    /* Remember the mutex we are using here.  If there is already a
       different address store this is a bad user bug.  Do not store
       anything for pshared condvars.  */
    if (cond->__data.__mutex != (void *) ~0l)
      cond->__data.__mutex = mutex;
  
    /* Prepare structure passed to cancellation handler.  */
    cbuffer.cond = cond;
    cbuffer.mutex = mutex;
  
    /* Before we block we enable cancellation.  Therefore we have to
       install a cancellation handler.  */
    __pthread_cleanup_push (&buffer, __condvar_cleanup, &cbuffer);
  
    /* The current values of the wakeup counter.  The "woken" counter
       must exceed this value.  */
    unsigned long long int val;
    unsigned long long int seq;
    val = seq = cond->__data.__wakeup_seq;
    /* Remember the broadcast counter.  */
    cbuffer.bc_seq = cond->__data.__broadcast_seq;
  
    do
      {
        unsigned int futex_val = cond->__data.__futex;
  
        /* Prepare to wait.  Release the condvar futex.  */
        lll_unlock (cond->__data.__lock, pshared);
  
        /* Enable asynchronous cancellation.  Required by the standard.  */
        cbuffer.oldtype = __pthread_enable_asynccancel ();
  
        /* Wait until woken by signal or broadcast.  */
        lll_futex_wait (&cond->__data.__futex, futex_val, pshared);
  
        /* Disable asynchronous cancellation.  */
        __pthread_disable_asynccancel (cbuffer.oldtype);
  
        /* We are going to look at shared data again, so get the lock.  */
        lll_lock (cond->__data.__lock, pshared);
  
        /* If a broadcast happened, we are done.  */
        if (cbuffer.bc_seq != cond->__data.__broadcast_seq)
  	goto bc_out;
  
        /* Check whether we are eligible for wakeup.  */
        val = cond->__data.__wakeup_seq;
      }
    while (val == seq || cond->__data.__woken_seq == val);
  
    /* Another thread woken up.  */
    ++cond->__data.__woken_seq;
  
   bc_out:
  
    cond->__data.__nwaiters -= 1 << COND_NWAITERS_SHIFT;
  
    /* If pthread_cond_destroy was called on this varaible already,
       notify the pthread_cond_destroy caller all waiters have left
       and it can be successfully destroyed.  */
    if (cond->__data.__total_seq == -1ULL
        && cond->__data.__nwaiters < (1 << COND_NWAITERS_SHIFT))
      lll_futex_wake (&cond->__data.__nwaiters, 1, pshared);
  
    /* We are done with the condvar.  */
    lll_unlock (cond->__data.__lock, pshared);
  
    /* The cancellation handling is back to normal, remove the handler.  */
    __pthread_cleanup_pop (&buffer, 0);
  
    /* Get the mutex before returning.  */
    return __pthread_mutex_cond_lock (mutex);
  }
  
  versioned_symbol (libpthread, __pthread_cond_wait, pthread_cond_wait,
  		  GLIBC_2_3_2);
  