/* Copyright (C) 2005-2014 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 _LOWLEVELLOCK_H
#define _LOWLEVELLOCK_H 1

#include <time.h>
#include <sys/param.h>
#include <bits/pthreadtypes.h>
#include <atomic.h>
#include <sysdep.h>
#include <kernel-features.h>
#include <tls.h>        /* Need THREAD_*, and header.*.  */

#define FUTEX_WAIT                      0
#define FUTEX_WAKE                      1
#define FUTEX_REQUEUE                   3
#define FUTEX_CMP_REQUEUE               4
#define FUTEX_WAKE_OP                   5
#define FUTEX_OP_CLEAR_WAKE_IF_GT_ONE   ((4 << 24) | 1)
#define FUTEX_LOCK_PI                   6
#define FUTEX_UNLOCK_PI                 7
#define FUTEX_TRYLOCK_PI                8
#define FUTEX_WAIT_BITSET               9
#define FUTEX_WAKE_BITSET               10
#define FUTEX_WAIT_REQUEUE_PI           11
#define FUTEX_CMP_REQUEUE_PI            12
#define FUTEX_PRIVATE_FLAG              128
#define FUTEX_CLOCK_REALTIME            256

#define FUTEX_BITSET_MATCH_ANY  0xffffffff

/* Values for 'private' parameter of locking macros.  Yes, the
   definition seems to be backwards.  But it is not.  The bit will be
   reversed before passing to the system call.  */
#define LLL_PRIVATE 0
#define LLL_SHARED  FUTEX_PRIVATE_FLAG


#if !defined NOT_IN_libc || defined IS_IN_rtld
/* In libc.so or ld.so all futexes are private.  */
# ifdef __ASSUME_PRIVATE_FUTEX
#  define __lll_private_flag(fl, private)                                      \
     ((fl) | FUTEX_PRIVATE_FLAG)
# else
#  define __lll_private_flag(fl, private)                                      \
     ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex))
# endif
#else
# ifdef __ASSUME_PRIVATE_FUTEX
#  define __lll_private_flag(fl, private) \
     (((fl) | FUTEX_PRIVATE_FLAG) ^ (private))
# else
#  define __lll_private_flag(fl, private)                                      \
     (__builtin_constant_p (private)                                           \
      ? ((private) == 0                                                        \
         ? ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex))          \
         : (fl))                                                               \
      : ((fl) | (((private) ^ FUTEX_PRIVATE_FLAG)                              \
          & THREAD_GETMEM (THREAD_SELF, header.private_futex))))
# endif
#endif


#define lll_futex_wait(futexp, val, private)                                   \
  lll_futex_timed_wait (futexp, val, NULL, private)

#define lll_futex_timed_wait(futexp, val, timespec, private)                   \
  ({                                                                           \
    INTERNAL_SYSCALL_DECL (__err);                                             \
    long int __ret;                                                            \
    __ret = INTERNAL_SYSCALL (futex, __err, 4, (long) (futexp),                \
                  __lll_private_flag (FUTEX_WAIT, private),                    \
                  (val), (timespec));                                          \
    __ret;                                                                     \
  })

#define lll_futex_timed_wait_bitset(futexp, val, timespec, clockbit, private)  \
  ({                                                                           \
    INTERNAL_SYSCALL_DECL (__err);                                             \
    long int __ret;                                                            \
    int __op = FUTEX_WAIT_BITSET | clockbit;                                   \
    __ret = INTERNAL_SYSCALL (futex, __err, 6, (long) (futexp),                \
                  __lll_private_flag (__op, private),                          \
                  (val), (timespec), NULL /* Unused.  */,                      \
                  FUTEX_BITSET_MATCH_ANY);                                     \
    __ret;                                                                     \
  })

#define lll_futex_wake(futexp, nr, private)                                    \
  ({                                                                           \
    INTERNAL_SYSCALL_DECL (__err);                                             \
    long int __ret;                                                            \
    __ret = INTERNAL_SYSCALL (futex, __err, 4, (long) (futexp),                \
                  __lll_private_flag (FUTEX_WAKE, private),                    \
                  (nr), 0);                                                    \
    __ret;                                                                     \
  })

/* Returns non-zero if error happened, zero if success.  */
#define lll_futex_requeue(futexp, nr_wake, nr_move, mutex, val, private)       \
  ({                                                                           \
    INTERNAL_SYSCALL_DECL (__err);                                             \
    long int __ret;                                                            \
    __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp),                       \
                  __lll_private_flag (FUTEX_CMP_REQUEUE, private),             \
                  (nr_wake), (nr_move), (mutex), (val));                       \
    INTERNAL_SYSCALL_ERROR_P (__ret, __err);                                   \
  })


/* Returns non-zero if error happened, zero if success.  */
#define lll_futex_wake_unlock(futexp, nr_wake, nr_wake2, futexp2, private)     \
  ({                                                                           \
    INTERNAL_SYSCALL_DECL (__err);                                             \
    long int __ret;                                                            \
                                                                               \
    __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp),                       \
                  __lll_private_flag (FUTEX_WAKE_OP, private),                 \
                  (nr_wake), (nr_wake2), (futexp2),                            \
                  FUTEX_OP_CLEAR_WAKE_IF_GT_ONE);                              \
    INTERNAL_SYSCALL_ERROR_P (__ret, __err);                                   \
  })

/* Priority Inheritance support.  */
#define lll_futex_wait_requeue_pi(futexp, val, mutex, private)                 \
  lll_futex_timed_wait_requeue_pi (futexp, val, NULL, 0, mutex, private)

#define lll_futex_timed_wait_requeue_pi(futexp, val, timespec, clockbit,       \
                                        mutex, private)                        \
  ({                                                                           \
    INTERNAL_SYSCALL_DECL (__err);                                             \
    long int __ret;                                                            \
    int __op = FUTEX_WAIT_REQUEUE_PI | clockbit;                               \
                                                                               \
    __ret = INTERNAL_SYSCALL (futex, __err, 5, (futexp),                       \
                  __lll_private_flag (__op, private),                          \
                  (val), (timespec), mutex);                                   \
    __ret;                                                                     \
  })

#define lll_futex_cmp_requeue_pi(futexp, nr_wake, nr_move, mutex, val, priv)   \
  ({                                                                           \
    INTERNAL_SYSCALL_DECL (__err);                                             \
    long int __ret;                                                            \
                                                                               \
    __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp),                       \
                  __lll_private_flag (FUTEX_CMP_REQUEUE_PI, priv),             \
                  (nr_wake), (nr_move), (mutex), (val));                       \
    INTERNAL_SYSCALL_ERROR_P (__ret, __err);                                   \
  })

#define lll_trylock(lock)                                                      \
  atomic_compare_and_exchange_val_acq(&(lock), 1, 0)

#define lll_cond_trylock(lock)                                                 \
  atomic_compare_and_exchange_val_acq(&(lock), 2, 0)

extern void __lll_lock_wait_private (int *futex) attribute_hidden;
extern void __lll_lock_wait (int *futex, int private) attribute_hidden;
extern int __lll_robust_lock_wait (int *futex, int private) attribute_hidden;

#define __lll_lock(futex, private)                                             \
  ((void) ({                                                                   \
    int *__futex = (futex);                                                    \
    if (__builtin_expect (atomic_compare_and_exchange_val_acq (__futex, 1, 0), \
              0) != 0)                                                         \
      {                                                                        \
    if (__builtin_constant_p (private) && (private) == LLL_PRIVATE)            \
      __lll_lock_wait_private (__futex);                                       \
    else                                                                       \
      __lll_lock_wait (__futex, private);                                      \
      }                                                                        \
  }))
#define lll_lock(futex, private) __lll_lock (&(futex), private)

#define __lll_robust_lock(futex, id, private)                                  \
  ({                                                                           \
    int *__futex = (futex);                                                    \
    int __val = 0;                                                             \
                                                                               \
    if (__builtin_expect (atomic_compare_and_exchange_bool_acq (__futex, id,   \
                                                                0), 0))        \
      __val = __lll_robust_lock_wait (__futex, private);                       \
    __val;                                                                     \
  })
#define lll_robust_lock(futex, id, private)                                    \
  __lll_robust_lock (&(futex), id, private)

static inline void __attribute__ ((always_inline))
__lll_cond_lock (int *futex, int private)
{
    if (__builtin_expect (atomic_exchange_acq (futex, 2), 0))
    __lll_lock_wait (futex, private);
}
#define lll_cond_lock(futex, private) __lll_cond_lock (&(futex), private)

#define lll_robust_cond_lock(futex, id, private)                               \
  __lll_robust_lock (&(futex), (id) | FUTEX_WAITERS, private)


extern int __lll_timedlock_wait (int *futex, const struct timespec *,
                 int private) attribute_hidden;
extern int __lll_robust_timedlock_wait (int *futex, const struct timespec *,
                    int private) attribute_hidden;

static inline int __attribute__ ((always_inline))
__lll_timedlock (int *futex, const struct timespec *abstime, int private)
{
  int result = 0;
  if (__builtin_expect (atomic_compare_and_exchange_val_acq (futex, 1, 0), 0) != 0)
    result = __lll_timedlock_wait (futex, abstime, private);
  return result;
}
#define lll_timedlock(futex, abstime, private)                                 \
  __lll_timedlock (&(futex), abstime, private)

static inline int __attribute__ ((always_inline))
__lll_robust_timedlock (int *futex, const struct timespec *abstime,
                        int id, int private)
{
  int result = 0;
  if (__builtin_expect (atomic_compare_and_exchange_bool_acq (futex, id, 0), 0))
    result = __lll_robust_timedlock_wait (futex, abstime, private);
  return result;
}
#define lll_robust_timedlock(futex, abstime, id, private)                      \
  __lll_robust_timedlock (&(futex), abstime, id, private)

#define __lll_unlock(futex, private)                                           \
  ((void) ({                                                                   \
    int *__futex = (futex);                                                    \
    int __val = atomic_exchange_rel (__futex, 0);                              \
                                                                               \
    if (__builtin_expect (__val > 1, 0))                                       \
      lll_futex_wake (__futex, 1, private);                                    \
  }))
#define lll_unlock(futex, private) __lll_unlock(&(futex), private)

#define __lll_robust_unlock(futex, private)                                    \
  ((void) ({                                                                   \
    int *__futex = (futex);                                                    \
    int __val = atomic_exchange_rel (__futex, 0);                              \
                                                                               \
    if (__builtin_expect (__val & FUTEX_WAITERS, 0))                           \
      lll_futex_wake (__futex, 1, private);                                    \
  }))
#define lll_robust_unlock(futex, private)                                      \
  __lll_robust_unlock(&(futex), private)

#define lll_islocked(futex)                                                    \
  (futex != 0)

/* Our internal lock implementation is identical to the binary-compatible
   mutex implementation.  */

/* Initializers for lock.  */
#define LLL_LOCK_INITIALIZER        (0)
#define LLL_LOCK_INITIALIZER_LOCKED (1)

/* The states of a lock are:
    0  -  untaken
    1  -  taken by one user
   >1  -  taken by more users.  */

/* The kernel notifies a process which uses CLONE_CHILD_CLEARTID via futex
   wakeup when the clone terminates.  The memory location contains the
   thread ID while the clone is running and is reset to zero
   afterwards.  */
#define lll_wait_tid(tid)                                                      \
  do {                                                                         \
    __typeof (tid) __tid;                                                      \
    while ((__tid = (tid)) != 0)                                               \
      lll_futex_wait (&(tid), __tid, LLL_SHARED);                              \
  } while (0)

extern int __lll_timedwait_tid (int *, const struct timespec *)
     attribute_hidden;

#define lll_timedwait_tid(tid, abstime)                                        \
  ({                                                                           \
    int __res = 0;                                                             \
    if ((tid) != 0)                                                            \
      __res = __lll_timedwait_tid (&(tid), (abstime));                         \
    __res;                                                                     \
  })

#endif  /* lowlevellock.h.  */
