text: /* Copyright (C) 2005, 2006, 2007, 2008, 2009 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; see the file COPYING.LIB.  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 <bits/kernel-features.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
  #define FUTEX_WAIT_BITSET	9
  #define FUTEX_WAKE_BITSET	10
  #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, (futexp),		      \
  			      __lll_private_flag (FUTEX_WAIT, private),	      \
  			      (val), (timespec));			      \
      __ret;								      \
    })
  
  #define lll_futex_wake(futexp, nr, private) \
    ({									      \
      INTERNAL_SYSCALL_DECL (__err);					      \
      long int __ret;							      \
      __ret = INTERNAL_SYSCALL (futex, __err, 4, (futexp),		      \
  			      __lll_private_flag (FUTEX_WAKE, private),	      \
  			      (nr), 0);					      \
      __ret;								      \
    })
  
  #define lll_robust_dead(futexv, private) \
    do									      \
      {									      \
        int *__futexp = &(futexv);					      \
        atomic_or (__futexp, FUTEX_OWNER_DIED);				      \
        lll_futex_wake (__futexp, 1, private);				      \
      }									      \
    while (0)
  
  /* 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);				      \
    })
  
  
  #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)
  
  #define __lll_robust_trylock(futex, id) \
    (atomic_compare_and_exchange_val_acq (futex, id, 0) != 0)
  #define lll_robust_trylock(lock, id) \
    __lll_robust_trylock (&(lock), id)
  
  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 (unlikely(atomic_compare_and_exchange_val_acq (__futex, 1, 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 (unlikely(atomic_compare_and_exchange_bool_acq (__futex, id, 0)))      \
        __val = __lll_robust_lock_wait (__futex, private);		      \
      __val;								      \
    })
  #define lll_robust_lock(futex, id, private) \
    __lll_robust_lock (&(futex), id, private)
  
  
  #define __lll_cond_lock(futex, private)					      \
    ((void) ({								      \
      int *__futex = (futex);						      \
      if (unlikely(atomic_exchange_acq (__futex, 2)))			      \
        __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;
  
  #define __lll_timedlock(futex, abstime, private)			      \
    ({									      \
       int *__futex = (futex);						      \
       int __val = 0;							      \
  									      \
       if (unlikely(atomic_exchange_acq (__futex, 1)))	                      \
         __val = __lll_timedlock_wait (__futex, abstime, private);	      \
       __val;								      \
    })
  #define lll_timedlock(futex, abstime, private) \
    __lll_timedlock (&(futex), abstime, private)
  
  
  #define __lll_robust_timedlock(futex, abstime, id, private)		      \
    ({									      \
      int *__futex = (futex);						      \
      int __val = 0;							      \
  									      \
      if (unlikely(atomic_compare_and_exchange_bool_acq (__futex, id, 0)))      \
        __val = __lll_robust_timedlock_wait (__futex, abstime, private);	      \
      __val;								      \
    })
  #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 __oldval = atomic_exchange_rel (__futex, 0);		\
         if (unlikely(__oldval > 1))			        \
  	 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 __oldval = atomic_exchange_rel (__futex, 0);		\
         if (unlikely(__oldval & FUTEX_WAITERS))	        	\
  	 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_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 */
  