/* futex operations for glibc-internal use.  Linux version.

   Copyright (C) 2014-2018 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, see

   <http://www.gnu.org/licenses/>.  */

#ifndef FUTEX_INTERNAL_H

#define FUTEX_INTERNAL_H

#include <sysdeps/nptl/futex-internal.h>

#include <errno.h>

#include <lowlevellock-futex.h>

#include <nptl/pthreadP.h>

/* See sysdeps/nptl/futex-internal.h for documentation; this file only

   contains Linux-specific comments.

   The Linux kernel treats provides absolute timeouts based on the

   CLOCK_REALTIME clock and relative timeouts measured against the

   CLOCK_MONOTONIC clock.

   We expect a Linux kernel version of 2.6.22 or more recent (since this

   version, EINTR is not returned on spurious wake-ups anymore).  */

/* FUTEX_SHARED is always supported by the Linux kernel.  */

static __always_inline int

futex_supports_pshared (int pshared)

{

  if (__glibc_likely (pshared == PTHREAD_PROCESS_PRIVATE))

    return 0;

  else if (pshared == PTHREAD_PROCESS_SHARED)

    return 0;

  else

    return EINVAL;

}

/* The Linux kernel supports relative timeouts measured against the

   CLOCK_MONOTONIC clock.  */

static __always_inline bool

futex_supports_exact_relative_timeouts (void)

{

  return true;

}

/* See sysdeps/nptl/futex-internal.h for details.  */

static __always_inline int

futex_wait (unsigned int *futex_word, unsigned int expected, int private)

{

  int err = lll_futex_timed_wait (futex_word, expected, NULL, private);

  switch (err)

    {

    case 0:

    case -EAGAIN:

    case -EINTR:

      return -err;

    case -ETIMEDOUT: /* Cannot have happened as we provided no timeout.  */

    case -EFAULT: /* Must have been caused by a glibc or application bug.  */

    case -EINVAL: /* Either due to wrong alignment or due to the timeout not

		     being normalized.  Must have been caused by a glibc or

		     application bug.  */

    case -ENOSYS: /* Must have been caused by a glibc bug.  */

    /* No other errors are documented at this time.  */

    default:

      futex_fatal_error ();

    }

}

/* See sysdeps/nptl/futex-internal.h for details.  */

static __always_inline int

futex_wait_cancelable (unsigned int *futex_word, unsigned int expected,

		       int private)

{

  int oldtype;

  oldtype = __pthread_enable_asynccancel ();

  int err = lll_futex_timed_wait (futex_word, expected, NULL, private);

  __pthread_disable_asynccancel (oldtype);

  switch (err)

    {

    case 0:

    case -EAGAIN:

    case -EINTR:

      return -err;

    case -ETIMEDOUT: /* Cannot have happened as we provided no timeout.  */

    case -EFAULT: /* Must have been caused by a glibc or application bug.  */

    case -EINVAL: /* Either due to wrong alignment or due to the timeout not

		     being normalized.  Must have been caused by a glibc or

		     application bug.  */

    case -ENOSYS: /* Must have been caused by a glibc bug.  */

    /* No other errors are documented at this time.  */

    default:

      futex_fatal_error ();

    }

}

/* See sysdeps/nptl/futex-internal.h for details.  */

static __always_inline int

futex_reltimed_wait (unsigned int *futex_word, unsigned int expected,

		     const struct timespec *reltime, int private)

{

  int err = lll_futex_timed_wait (futex_word, expected, reltime, private);

  switch (err)

    {

    case 0:

    case -EAGAIN:

    case -EINTR:

    case -ETIMEDOUT:

      return -err;

    case -EFAULT: /* Must have been caused by a glibc or application bug.  */

    case -EINVAL: /* Either due to wrong alignment or due to the timeout not

		     being normalized.  Must have been caused by a glibc or

		     application bug.  */

    case -ENOSYS: /* Must have been caused by a glibc bug.  */

    /* No other errors are documented at this time.  */

    default:

      futex_fatal_error ();

    }

}

/* See sysdeps/nptl/futex-internal.h for details.  */

static __always_inline int

futex_reltimed_wait_cancelable (unsigned int *futex_word,

				unsigned int expected,

			        const struct timespec *reltime, int private)

{

  int oldtype;

  oldtype = __pthread_enable_asynccancel ();

  int err = lll_futex_timed_wait (futex_word, expected, reltime, private);

  __pthread_disable_asynccancel (oldtype);

  switch (err)

    {

    case 0:

    case -EAGAIN:

    case -EINTR:

    case -ETIMEDOUT:

      return -err;

    case -EFAULT: /* Must have been caused by a glibc or application bug.  */

    case -EINVAL: /* Either due to wrong alignment or due to the timeout not

		     being normalized.  Must have been caused by a glibc or

		     application bug.  */

    case -ENOSYS: /* Must have been caused by a glibc bug.  */

    /* No other errors are documented at this time.  */

    default:

      futex_fatal_error ();

    }

}

/* See sysdeps/nptl/futex-internal.h for details.  */

static __always_inline int

futex_abstimed_wait (unsigned int *futex_word, unsigned int expected,

		     const struct timespec *abstime, int private)

{

  /* Work around the fact that the kernel rejects negative timeout values

     despite them being valid.  */

  if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))

    return ETIMEDOUT;

  int err = lll_futex_timed_wait_bitset (futex_word, expected, abstime,

					 FUTEX_CLOCK_REALTIME, private);

  switch (err)

    {

    case 0:

    case -EAGAIN:

    case -EINTR:

    case -ETIMEDOUT:

      return -err;

    case -EFAULT: /* Must have been caused by a glibc or application bug.  */

    case -EINVAL: /* Either due to wrong alignment or due to the timeout not

		     being normalized.  Must have been caused by a glibc or

		     application bug.  */

    case -ENOSYS: /* Must have been caused by a glibc bug.  */

    /* No other errors are documented at this time.  */

    default:

      futex_fatal_error ();

    }

}

/* See sysdeps/nptl/futex-internal.h for details.  */

static __always_inline int

futex_abstimed_wait_cancelable (unsigned int *futex_word,

				unsigned int expected,

			        const struct timespec *abstime, int private)

{

  /* Work around the fact that the kernel rejects negative timeout values

     despite them being valid.  */

  if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))

    return ETIMEDOUT;

  int oldtype;

  oldtype = __pthread_enable_asynccancel ();

  int err = lll_futex_timed_wait_bitset (futex_word, expected, abstime,

					 FUTEX_CLOCK_REALTIME, private);

  __pthread_disable_asynccancel (oldtype);

  switch (err)

    {

    case 0:

    case -EAGAIN:

    case -EINTR:

    case -ETIMEDOUT:

      return -err;

    case -EFAULT: /* Must have been caused by a glibc or application bug.  */

    case -EINVAL: /* Either due to wrong alignment or due to the timeout not

		     being normalized.  Must have been caused by a glibc or

		     application bug.  */

    case -ENOSYS: /* Must have been caused by a glibc bug.  */

    /* No other errors are documented at this time.  */

    default:

      futex_fatal_error ();

    }

}

/* See sysdeps/nptl/futex-internal.h for details.  */

static __always_inline void

futex_wake (unsigned int *futex_word, int processes_to_wake, int private)

{

  int res = lll_futex_wake (futex_word, processes_to_wake, private);

  /* No error.  Ignore the number of woken processes.  */

  if (res >= 0)

    return;

  switch (res)

    {

    case -EFAULT: /* Could have happened due to memory reuse.  */

    case -EINVAL: /* Could be either due to incorrect alignment (a bug in

		     glibc or in the application) or due to memory being

		     reused for a PI futex.  We cannot distinguish between the

		     two causes, and one of them is correct use, so we do not

		     act in this case.  */

      return;

    case -ENOSYS: /* Must have been caused by a glibc bug.  */

    /* No other errors are documented at this time.  */

    default:

      futex_fatal_error ();

    }

}

#endif  /* futex-internal.h */