Checking patch nptl/pthread_cond_common.c...
error: while searching for:
     * New waiters arriving concurrently with the group switching will all go
       into G2 until we atomically make the switch.  Waiters existing in G2
       are not affected.
     * Waiters in G1 will be closed out immediately by setting a flag in
       __g_signals, which will prevent waiters from blocking using a futex on
       __g_signals and also notifies them that the group is closed.  As a
       result, they will eventually remove their group reference, allowing us
       to close switch group roles.  */

  /* First, set the closed flag on __g_signals.  This tells waiters that are
     about to wait that they shouldn't do that anymore.  This basically
     serves as an advance notificaton of the upcoming change to __g1_start;
     waiters interpret it as if __g1_start was larger than their waiter
     sequence position.  This allows us to change __g1_start after waiting
     for all existing waiters with group references to leave, which in turn
     makes recovery after stealing a signal simpler because it then can be
     skipped if __g1_start indicates that the group is closed (otherwise,
     we would have to recover always because waiters don't know how big their
     groups are).  Relaxed MO is fine.  */
  atomic_fetch_or_relaxed (cond->__data.__g_signals + g1, 1);

  /* Wait until there are no group references anymore.  The fetch-or operation
     injects us into the modification order of __g_refs; release MO ensures
     that waiters incrementing __g_refs after our fetch-or see the previous
     changes to __g_signals and to __g1_start that had to happen before we can
     switch this G1 and alias with an older group (we have two groups, so
     aliasing requires switching group roles twice).  Note that nobody else
     can have set the wake-request flag, so we do not have to act upon it.

     Also note that it is harmless if older waiters or waiters from this G1
     get a group reference after we have quiesced the group because it will
     remain closed for them either because of the closed flag in __g_signals
     or the later update to __g1_start.  New waiters will never arrive here
     but instead continue to go into the still current G2.  */
  unsigned r = atomic_fetch_or_release (cond->__data.__g_refs + g1, 0);
  while ((r >> 1) > 0)
    {
      for (unsigned int spin = maxspin; ((r >> 1) > 0) && (spin > 0); spin--)
	{
	  /* TODO Back off.  */
	  r = atomic_load_relaxed (cond->__data.__g_refs + g1);
	}
      if ((r >> 1) > 0)
	{
	  /* There is still a waiter after spinning.  Set the wake-request
	     flag and block.  Relaxed MO is fine because this is just about
	     this futex word.

	     Update r to include the set wake-request flag so that the upcoming
	     futex_wait only blocks if the flag is still set (otherwise, we'd
	     violate the basic client-side futex protocol).  */
	  r = atomic_fetch_or_relaxed (cond->__data.__g_refs + g1, 1) | 1;

	  if ((r >> 1) > 0)
	    futex_wait_simple (cond->__data.__g_refs + g1, r, private);
	  /* Reload here so we eventually see the most recent value even if we
	     do not spin.   */
	  r = atomic_load_relaxed (cond->__data.__g_refs + g1);
	}
    }
  /* Acquire MO so that we synchronize with the release operation that waiters
     use to decrement __g_refs and thus happen after the waiters we waited
     for.  */
  atomic_thread_fence_acquire ();

  /* Update __g1_start, which finishes closing this group.  The value we add
     will never be negative because old_orig_size can only be zero when we
     switch groups the first time after a condvar was initialized, in which
     case G1 will be at index 1 and we will add a value of 1.  See above for
     why this takes place after waiting for quiescence of the group.
     Relaxed MO is fine because the change comes with no additional
     constraints that others would have to observe.  */
  __condvar_add_g1_start_relaxed (cond,
      (old_orig_size << 1) + (g1 == 1 ? 1 : - 1));

  /* Now reopen the group, thus enabling waiters to again block using the
     futex controll
error: patch failed: nptl/pthread_cond_common.c:222
error: nptl/pthread_cond_common.c: patch does not apply
Checking patch nptl/pthread_cond_wait.c...
error: while searching for:
  while (!atomic_compare_exchange_weak_acquire (cond->__data.__g_signals + g,
						&signals, signals - 2));

  /* We consumed a signal but we could have consumed from a more recent group
     that aliased with ours due to being in the same group slot.  If this
     might be the case our group must be closed as visible through
     __g1_start.  */
  uint64_t g1_start = __condvar_load_g1_start_relaxed (cond);
  if (seq < (g1_start >> 1))
    {
      /* We potentially stole a signal from a more recent group but we do not
	 know which group we really consumed from.
	 We do not care about groups older than current G1 because they are
	 closed; we could have stolen from these, but then we just add a
	 spurious wake-up for the current groups.
	 We will never steal a signal from current G2 that was really intended
	 for G2 because G2 never receives signals (until it becomes G1).  We
	 could have stolen a signal from G2 that was conservatively added by a
	 previous waiter that also thought it stole a signal -- but given that
	 that signal was added unnecessarily, it's not a problem if we steal
	 it.
	 Thus, the remaining case is that we could have stolen from the current
	 G1, where "current" means the __g1_start value we observed.  However,
	 if the current G1 does not have the same slot index as we do, we did
	 not steal from it and do not need to undo that.  This is the reason
	 for putting a bit with G2's index into__g1_start as well.  */
      if (((g1_start & 1) ^ 1) == g)
	{
	  /* We have to conservatively undo our potential mistake of stealing
	     a signal.  We can stop trying to do that when the current G1
	     changes because other spinning waiters will notice this too and
	     __condvar_quiesce_and_switch_g1 has checked that there are no
	     futex waiters anymore before switching G1.
	     Relaxed MO is fine for the __g1_start load because we need to
	     merely be able to observe this fact and not have to observe
	     something else as well.
	     ??? Would it help to spin for a little while to see whether the
	     current G1 gets closed?  This might be worthwhile if the group is
	     small or close to being closed.  */
	  unsigned int s = atomic_load_relaxed (cond->__data.__g_signals + g);
	  while (__condvar_load_g1_start_relaxed (cond) == g1_start)
	    {
	      /* Try to add a signal.  We don't need to acquire the lock
		 because at worst we can cause a spurious wake-up.  If the
		 group is in the process of being closed (LSB is true), this
		 has an effect similar to us adding a signal.  */
	      if (((s & 1) != 0)
		  || atomic_compare_exchange_weak_relaxed
		       (cond->__data.__g_signals + g, &s, s + 2))
		{
		  /* If we added a signal, we also need to add a wake-up on
		     the futex.  We also need to do that if we skipped adding
		     a signal because the group is being closed because
		     while __condvar_quiesce_and_switch_g1 could have closed
		     the group, it might stil be waiting for futex waiters to
		     leave (and one of those waiters might be the one we stole
		     the signal from, which cause it to block using the
		     futex).  */
		  futex_wake (cond->__data.__g_signals + g, 1, private);
		  break;
		}
	      /* TODO Back off.  */
	    }
	}
    }

 done:

  /* Confirm that we have been woken.  We do that before acquiring the mutex

error: patch failed: nptl/pthread_cond_wait.c:532
error: nptl/pthread_cond_wait.c: patch does not apply