lowlevellock.h

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/* Copyright (C) 2003, 2004, 2006 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Jakub Jelinek <[e-mail]>, 2003.

   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 Libr	\ary; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#ifndef _LOWLEVELLOCK_H
#define _LOWLEVELLOCK_H	1

#include <time.h>
#include <sys/param.h>
#include <bits/pthreadtypes.h>
#include <atomic.h>


#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

/* Initializer for compatibility lock.	*/
#define LLL_MUTEX_LOCK_INITIALIZER (0)

#define lll_futex_wait(futexp, val) \
  ({									      \
    INTERNAL_SYSCALL_DECL (__err);					      \
    long int __ret;							      \
									      \
    __ret = INTERNAL_SYSCALL (futex, __err, 4,				      \
			      (futexp), FUTEX_WAIT, (val), 0);		      \
    __ret;								      \
  })

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

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

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

#define lll_robust_mutex_dead(futexv) \
  do									      \
    {									      \
      int *__futexp = &(futexv);					      \
      atomic_or (__futexp, FUTEX_OWNER_DIED);				      \
      lll_futex_wake (__futexp, 1);					      \
    }									      \
  while (0)

/* Returns non-zero if error happened, zero if success.  */
#ifdef __sparc32_atomic_do_lock
/* Avoid FUTEX_WAKE_OP if supporting pre-v9 CPUs.  */
# define lll_futex_wake_unlock(futexp, nr_wake, nr_wake2, futexp2) 1
#else
# define lll_futex_wake_unlock(futexp, nr_wake, nr_wake2, futexp2) \
  ({									      \
    INTERNAL_SYSCALL_DECL (__err);					      \
    long int __ret;							      \
									      \
    __ret = INTERNAL_SYSCALL (futex, __err, 6,				      \
			      (futexp), FUTEX_WAKE_OP, (nr_wake),	      \
			      (nr_wake2), (futexp2),			      \
			      FUTEX_OP_CLEAR_WAKE_IF_GT_ONE);		      \
    INTERNAL_SYSCALL_ERROR_P (__ret, __err);				      \
  })
#endif

static inline int
__attribute__ ((always_inline))
__lll_mutex_trylock (int *futex)
{
  return atomic_compare_and_exchange_val_24_acq (futex, 1, 0) != 0;
}
#define lll_mutex_trylock(futex) __lll_mutex_trylock (&(futex))

static inline int
__attribute__ ((always_inline))
__lll_mutex_cond_trylock (int *futex)
{
  return atomic_compare_and_exchange_val_24_acq (futex, 2, 0) != 0;
}
#define lll_mutex_cond_trylock(futex) __lll_mutex_cond_trylock (&(futex))

static inline int
__attribute__ ((always_inline))
__lll_robust_mutex_trylock (int *futex, int id)
{
  return atomic_compare_and_exchange_val_acq (futex, id, 0) != 0;
}
#define lll_robust_mutex_trylock(futex, id) \
  __lll_robust_mutex_trylock (&(futex), id)


extern void __lll_lock_wait (int *futex) attribute_hidden;
extern int __lll_robust_lock_wait (int *futex) attribute_hidden;

static inline void
__attribute__ ((always_inline))
__lll_mutex_lock (int *futex)
{
  int val = atomic_compare_and_exchange_val_24_acq (futex, 1, 0);

  if (__builtin_expect (val != 0, 0))
    __lll_lock_wait (futex);
}
#define lll_mutex_lock(futex) __lll_mutex_lock (&(futex))

static inline int
__attribute__ ((always_inline))
__lll_robust_mutex_lock (int *futex, int id)
{
  int result = 0;
  if (atomic_compare_and_exchange_bool_acq (futex, id, 0) != 0)
    result = __lll_robust_lock_wait (futex);
  return result;
}
#define lll_robust_mutex_lock(futex, id) \
  __lll_robust_mutex_lock (&(futex), id)

static inline void
__attribute__ ((always_inline))
__lll_mutex_cond_lock (int *futex)
{
  int val = atomic_compare_and_exchange_val_24_acq (futex, 2, 0);

  if (__builtin_expect (val != 0, 0))
    __lll_lock_wait (futex);
}
#define lll_mutex_cond_lock(futex) __lll_mutex_cond_lock (&(futex))

#define lll_robust_mutex_cond_lock(futex, id) \
  __lll_robust_mutex_lock (&(futex), (id) | FUTEX_WAITERS)


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

static inline int
__attribute__ ((always_inline))
__lll_mutex_timedlock (int *futex, const struct timespec *abstime)
{
  int val = atomic_compare_and_exchange_val_24_acq (futex, 1, 0);
  int result = 0;

  if (__builtin_expect (val != 0, 0))
    result = __lll_timedlock_wait (futex, abstime);
  return result;
}
#define lll_mutex_timedlock(futex, abstime) \
  __lll_mutex_timedlock (&(futex), abstime)

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

#define lll_mutex_unlock(lock) \
  ((void) ({								      \
    int *__futex = &(lock);						      \
    int __val = atomic_exchange_24_rel (__futex, 0);			      \
    if (__builtin_expect (__val > 1, 0))				      \
      lll_futex_wake (__futex, 1);					      \
  }))

#define lll_robust_mutex_unlock(lock) \
  ((void) ({								      \
    int *__futex = &(lock);						      \
    int __val = atomic_exchange_rel (__futex, 0);			      \
    if (__builtin_expect (__val & FUTEX_WAITERS, 0))			      \
      lll_futex_wake (__futex, 1);					      \
  }))

#define lll_mutex_unlock_force(lock) \
  ((void) ({								      \
    int *__futex = &(lock);						      \
    (void) atomic_exchange_24_rel (__futex, 0);				      \
    lll_futex_wake (__futex, 1);					      \
  }))

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


/* We have a separate internal lock implementation which is not tied
   to binary compatibility.  We can use the lll_mutex_*.  */

/* Type for lock object.  */
typedef int lll_lock_t;

extern int lll_unlock_wake_cb (int *__futex) attribute_hidden;

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

#define lll_trylock(futex)	lll_mutex_trylock (futex)
#define lll_lock(futex)		lll_mutex_lock (futex)
#define lll_unlock(futex)	lll_mutex_unlock (futex)
#define lll_islocked(futex)	lll_mutex_islocked (futex)


/* The kernel notifies a process with uses CLONE_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);		\
    }						\
  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;						\
  })


/* Conditional variable handling.  */

extern void __lll_cond_wait (pthread_cond_t *cond)
     attribute_hidden;
extern int __lll_cond_timedwait (pthread_cond_t *cond,
				 const struct timespec *abstime)
     attribute_hidden;
extern void __lll_cond_wake (pthread_cond_t *cond)
     attribute_hidden;
extern void __lll_cond_broadcast (pthread_cond_t *cond)
     attribute_hidden;

#define lll_cond_wait(cond) \
  __lll_cond_wait (cond)
#define lll_cond_timedwait(cond, abstime) \
  __lll_cond_timedwait (cond, abstime)
#define lll_cond_wake(cond) \
  __lll_cond_wake (cond)
#define lll_cond_broadcast(cond) \
  __lll_cond_broadcast (cond)

#endif	/* lowlevellock.h */