glibc/nptl/sysdeps/pthread/aio_misc.h

/* Copyright (C) 2006, 2007 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

/* We define a special synchronization primitive for AIO.  POSIX
   conditional variables would be ideal but the pthread_cond_*wait
   operations do not return on EINTR.  This is a requirement for
   correct aio_suspend and lio_listio implementations.  */

#include <assert.h>
#include <pthreadP.h>
#include <lowlevellock.h>

#define DONT_NEED_AIO_MISC_COND	1

#define AIO_MISC_NOTIFY(waitlist) \
  do {									      \
    if (*waitlist->counterp > 0 && --*waitlist->counterp == 0)		      \
      lll_private_futex_wake (waitlist->counterp, 1);			      \
  } while (0)

#define AIO_MISC_WAIT(result, futex, timeout, cancel)			      \
  do {									      \
    volatile int *futexaddr = &futex;					      \
    int oldval = futex;							      \
									      \
    if (oldval != 0)							      \
      {									      \
	pthread_mutex_unlock (&__aio_requests_mutex);			      \
									      \
	int oldtype;							      \
	if (cancel)							      \
	  oldtype = LIBC_CANCEL_ASYNC ();				      \
									      \
	int status;							      \
	do								      \
	  {								      \
	    status = lll_private_futex_timed_wait (futexaddr, oldval,	      \
						   timeout);		      \
	    if (status != -EWOULDBLOCK)					      \
	      break;							      \
									      \
	    oldval = *futexaddr;					      \
	  }								      \
	while (oldval != 0);						      \
									      \
	if (cancel)							      \
	  LIBC_CANCEL_RESET (oldtype);					      \
									      \
	if (status == -EINTR)						      \
	  result = EINTR;						      \
	else if (status == -ETIMEDOUT)					      \
	  result = EAGAIN;						      \
	else								      \
	  assert (status == 0 || status == -EWOULDBLOCK);		      \
									      \
	pthread_mutex_lock (&__aio_requests_mutex);			      \
      }									      \
  } while (0)

#include_next <aio_misc.h>