path: root/rtkaio/sysdeps/unix/sysv/linux/kaio_suspend.c

/* Suspend until termination of a requests.
   Copyright (C) 1997, 1998, 1999, 2000, 2002, 2003, 2006
   Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.

   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 use an UGLY hack to prevent gcc from finding us cheating.  The
   implementations of aio_suspend and aio_suspend64 are identical and so
   we want to avoid code duplication by using aliases.  But gcc sees
   the different parameter lists and prints a warning.  We define here
   a function so that aio_suspend64 has no prototype.  */
#define aio_suspend64 XXX
#include <aio.h>
/* And undo the hack.  */
#undef aio_suspend64

#include <kaio_misc.h>

#ifndef USE_KAIO
#include <aio_suspend.c>
#else

#include <assert.h>
#include <errno.h>
#include <stdbool.h>
#include <stdlib.h>
#include <sys/time.h>

#include <bits/libc-lock.h>
#include <sysdep-cancel.h>


struct clparam
{
  const struct aiocb *const *list;
  struct waitlist *waitlist;
  struct requestlist **requestlist;
#ifndef DONT_NEED_AIO_MISC_COND
  pthread_cond_t *cond;
#endif
  int nent;
};


static void
cleanup (void *arg)
{
#ifdef DONT_NEED_AIO_MISC_COND
  /* Acquire the mutex.  If pthread_cond_*wait is used this would
     happen implicitly.  */
  pthread_mutex_lock (&__aio_requests_mutex);
#endif

  const struct clparam *param = (const struct clparam *) arg;

  /* Now remove the entry in the waiting list for all requests
     which didn't terminate.  */
  int cnt = param->nent;
  while (cnt-- > 0)
    if (param->list[cnt] != NULL
	&& param->list[cnt]->__error_code == EINPROGRESS)
      {
	struct waitlist **listp;

	assert (param->requestlist[cnt] != NULL);

	/* There is the chance that we cannot find our entry anymore. This
	   could happen if the request terminated and restarted again.  */
	listp = &param->requestlist[cnt]->waiting;
	while (*listp != NULL && *listp != &param->waitlist[cnt])
	  listp = &(*listp)->next;

	if (*listp != NULL)
	  *listp = (*listp)->next;
      }

#ifndef DONT_NEED_AIO_MISC_COND
  /* Release the conditional variable.  */
  (void) pthread_cond_destroy (param->cond);
#endif

  /* Release the mutex.  */
  pthread_mutex_unlock (&__aio_requests_mutex);
}


int
aio_suspend (list, nent, timeout)
     const struct aiocb *const list[];
     int nent;
     const struct timespec *timeout;
{
  if (__builtin_expect (nent < 0, 0))
    {
      __set_errno (EINVAL);
      return -1;
    }

  struct waitlist waitlist[nent];
  struct requestlist *requestlist[nent];
#ifndef DONT_NEED_AIO_MISC_COND
  pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
#endif
  int cnt;
  int result = 0;
  int cntr = 1;
  int total = 0, ktotal = 0;

  /* Request the mutex.  */
  pthread_mutex_lock (&__aio_requests_mutex);

  /* There is not yet a finished request.  Signal the request that
     we are working for it.  */
  for (cnt = 0; cnt < nent; ++cnt)
    if (list[cnt] != NULL)
      {
	if (list[cnt]->__error_code == EINPROGRESS)
	  {
	    requestlist[cnt] = __aio_find_req ((aiocb_union *) list[cnt]);

	    if (requestlist[cnt] != NULL)
	      {
#ifndef DONT_NEED_AIO_MISC_COND
		waitlist[cnt].cond = &cond;
#endif
		waitlist[cnt].result = NULL;
		waitlist[cnt].next = requestlist[cnt]->waiting;
		waitlist[cnt].counterp = &cntr;
		waitlist[cnt].sigevp = NULL;
#ifdef BROKEN_THREAD_SIGNALS
		waitlist[cnt].caller_pid = 0;	/* Not needed.  */
#endif
		requestlist[cnt]->waiting = &waitlist[cnt];
		total++;
		if (requestlist[cnt]->kioctx != KCTX_NONE)
		  ktotal++;
	      }
	    else
	      /* We will never suspend.  */
	      break;
	  }
	else
	  /* We will never suspend.  */
	  break;
      }


  /* Only if none of the entries is NULL or finished to be wait.  */
  if (cnt == nent && total)
    {
      struct clparam clparam =
	{
	  .list = list,
	  .waitlist = waitlist,
	  .requestlist = requestlist,
#ifndef DONT_NEED_AIO_MISC_COND
	  .cond = &cond,
#endif
	  .nent = nent
	};

      pthread_cleanup_push (cleanup, &clparam);

      if (!__kernel_thread_started && ktotal)
	{
	  /* If the kernel aio thread was not started yet all requests
	     are served by the kernel and there are no other threads running,
	     read events with mutex hold, so that nobody else can get them
	     instead of us here.  */
          if (SINGLE_THREAD_P && total == ktotal)
	    {
	      if (timeout == NULL)
		{
		  while (cntr == 1)
		    __aio_wait_for_events (__aio_kioctx, NULL);
		}
	      else
		{
		  struct timeval now;
		  struct timespec abstime, ts;

		  __gettimeofday (&now, NULL);
		  abstime.tv_nsec = timeout->tv_nsec + now.tv_usec * 1000;
		  abstime.tv_sec = timeout->tv_sec + now.tv_sec;
		  if (abstime.tv_nsec >= 1000000000)
		    {
		      abstime.tv_nsec -= 1000000000;
		      abstime.tv_sec += 1;
		    }

		  for (;;)
		    {
		      result = __aio_wait_for_events (__aio_kioctx, timeout);
		      if (cntr < 1)
			break;
		      if (result == ETIMEDOUT)
			break;

		      __gettimeofday (&now, NULL);
		      if (now.tv_sec > abstime.tv_sec
			  || (now.tv_sec == abstime.tv_sec
			      && now.tv_usec * 1000 >= abstime.tv_nsec))
			break;

		      ts.tv_nsec = abstime.tv_nsec - now.tv_usec * 1000;
		      ts.tv_sec = abstime.tv_sec - now.tv_sec;
		      if (abstime.tv_nsec < now.tv_usec * 1000)
			{
			  ts.tv_nsec += 1000000000;
			  ts.tv_sec -= 1;
			}
		      timeout = &ts;
		    }

		  if (cntr < 1)
		    result = 0;
		  else
		    result = ETIMEDOUT;
		}
	      total = 0;
	    }
 	  else if (__aio_create_kernel_thread () < 0)
	    {
	      total = 0;
	      __set_errno (ENOMEM);
	      result = -1;
	    }
	}

      if (total == 0)
	/* Suspending was handled above.  */
	;
#ifdef DONT_NEED_AIO_MISC_COND
      else
	AIO_MISC_WAIT (result, cntr, timeout, 1);
#else
      else if (timeout == NULL)
	result = pthread_cond_wait (&cond, &__aio_requests_mutex);
      else
	{
	  /* We have to convert the relative timeout value into an
	     absolute time value with pthread_cond_timedwait expects.  */
	  struct timeval now;
	  struct timespec abstime;

	  __gettimeofday (&now, NULL);
	  abstime.tv_nsec = timeout->tv_nsec + now.tv_usec * 1000;
	  abstime.tv_sec = timeout->tv_sec + now.tv_sec;
	  if (abstime.tv_nsec >= 1000000000)
	    {
	      abstime.tv_nsec -= 1000000000;
	      abstime.tv_sec += 1;
	    }

	  result = pthread_cond_timedwait (&cond, &__aio_requests_mutex,
					   &abstime);
	}
#endif

      pthread_cleanup_pop (0);
    }

  /* Now remove the entry in the waiting list for all requests
     which didn't terminate.  */
  while (cnt-- > 0)
    if (list[cnt] != NULL && list[cnt]->__error_code == EINPROGRESS)
      {
	struct waitlist **listp;

	assert (requestlist[cnt] != NULL);

	/* There is the chance that we cannot find our entry anymore. This
	   could happen if the request terminated and restarted again.  */
	listp = &requestlist[cnt]->waiting;
	while (*listp != NULL && *listp != &waitlist[cnt])
	  listp = &(*listp)->next;

	if (*listp != NULL)
	  *listp = (*listp)->next;
      }

#ifndef DONT_NEED_AIO_MISC_COND
  /* Release the conditional variable.  */
  if (__builtin_expect (pthread_cond_destroy (&cond) != 0, 0))
    /* This must never happen.  */
    abort ();
#endif

  if (result != 0)
    {
#ifndef DONT_NEED_AIO_MISC_COND
      /* An error occurred.  Possibly it's ETIMEDOUT.  We have to translate
	 the timeout error report of `pthread_cond_timedwait' to the
	 form expected from `aio_suspend'.  */
      if (result == ETIMEDOUT)
	__set_errno (EAGAIN);
      else
#endif
	__set_errno (result);

      result = -1;
    }

  /* Release the mutex.  */
  pthread_mutex_unlock (&__aio_requests_mutex);

  return result;
}

weak_alias (aio_suspend, aio_suspend64)
#endif