mach/lock-intern.h

   1 /* Copyright (C) 1994-2017 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _LOCK_INTERN_H
  19 #define _LOCK_INTERN_H
  20
  21 #include <sys/cdefs.h>
  22 #include <machine-lock.h>
  23
  24 #ifndef _EXTERN_INLINE
  25 #define _EXTERN_INLINE __extern_inline
  26 #endif
  27
  28
  29 /* Initialize LOCK.  */
  30
  31 _EXTERN_INLINE void
  32 __spin_lock_init (__spin_lock_t *__lock)
  33 {
  34   *__lock = __SPIN_LOCK_INITIALIZER;
  35 }
  36
  37
  38 /* Lock LOCK, blocking if we can't get it.  */
  39 extern void __spin_lock_solid (__spin_lock_t *__lock);
  40
  41 /* Lock the spin lock LOCK.  */
  42
  43 _EXTERN_INLINE void
  44 __spin_lock (__spin_lock_t *__lock)
  45 {
  46   if (! __spin_try_lock (__lock))
  47     __spin_lock_solid (__lock);
  48 }
  49 \f
  50 /* Name space-clean internal interface to mutex locks.
  51
  52    Code internal to the C library uses these functions to lock and unlock
  53    mutex locks.  These locks are of type `struct mutex', defined in
  54    <cthreads.h>.  The functions here are name space-clean.  If the program
  55    is linked with the cthreads library, `__mutex_lock_solid' and
  56    `__mutex_unlock_solid' will invoke the corresponding cthreads functions
  57    to implement real mutex locks.  If not, simple stub versions just use
  58    spin locks.  */
  59
  60
  61 /* Initialize the newly allocated mutex lock LOCK for further use.  */
  62 extern void __mutex_init (void *__lock);
  63
  64 /* Lock LOCK, blocking if we can't get it.  */
  65 extern void __mutex_lock_solid (void *__lock);
  66
  67 /* Finish unlocking LOCK, after the spin lock LOCK->held has already been
  68    unlocked.  This function will wake up any thread waiting on LOCK.  */
  69 extern void __mutex_unlock_solid (void *__lock);
  70
  71 /* Lock the mutex lock LOCK.  */
  72
  73 _EXTERN_INLINE void
  74 __mutex_lock (void *__lock)
  75 {
  76   if (! __spin_try_lock ((__spin_lock_t *) __lock))
  77     __mutex_lock_solid (__lock);
  78 }
  79
  80 /* Unlock the mutex lock LOCK.  */
  81
  82 _EXTERN_INLINE void
  83 __mutex_unlock (void *__lock)
  84 {
  85   __spin_unlock ((__spin_lock_t *) __lock);
  86   __mutex_unlock_solid (__lock);
  87 }
  88
  89
  90 _EXTERN_INLINE int
  91 __mutex_trylock (void *__lock)
  92 {
  93   return __spin_try_lock ((__spin_lock_t *) __lock);
  94 }
  95
  96 #endif /* lock-intern.h */