ports/sysdeps/unix/sysv/linux/alpha/nptl/lowlevellock.h

   1 /* Copyright (C) 2003, 2004, 2006, 2007 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 _LOWLEVELLOCK_H
  19 #define _LOWLEVELLOCK_H 1
  20
  21 #include <time.h>
  22 #include <sys/param.h>
  23 #include <bits/pthreadtypes.h>
  24 #include <atomic.h>
  25 #include <sysdep.h>
  26 #include <kernel-features.h>
  27
  28
  29 #define __NR_futex              394
  30 #define FUTEX_WAIT              0
  31 #define FUTEX_WAKE              1
  32 #define FUTEX_REQUEUE           3
  33 #define FUTEX_CMP_REQUEUE       4
  34 #define FUTEX_WAKE_OP           5
  35 #define FUTEX_OP_CLEAR_WAKE_IF_GT_ONE   ((4 << 24) | 1)
  36 #define FUTEX_LOCK_PI           6
  37 #define FUTEX_UNLOCK_PI         7
  38 #define FUTEX_TRYLOCK_PI        8
  39 #define FUTEX_WAIT_BITSET       9
  40 #define FUTEX_WAKE_BITSET       10
  41 #define FUTEX_PRIVATE_FLAG      128
  42 #define FUTEX_CLOCK_REALTIME    256
  43
  44 #define FUTEX_BITSET_MATCH_ANY  0xffffffff
  45
  46 /* Values for 'private' parameter of locking macros.  Yes, the
  47    definition seems to be backwards.  But it is not.  The bit will be
  48    reversed before passing to the system call.  */
  49 #define LLL_PRIVATE     0
  50 #define LLL_SHARED      FUTEX_PRIVATE_FLAG
  51
  52
  53 #if !defined NOT_IN_libc || defined IS_IN_rtld
  54 /* In libc.so or ld.so all futexes are private.  */
  55 # ifdef __ASSUME_PRIVATE_FUTEX
  56 #  define __lll_private_flag(fl, private) \
  57   ((fl) | FUTEX_PRIVATE_FLAG)
  58 # else
  59 #  define __lll_private_flag(fl, private) \
  60   ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex))
  61 # endif
  62 #else
  63 # ifdef __ASSUME_PRIVATE_FUTEX
  64 #  define __lll_private_flag(fl, private) \
  65   (((fl) | FUTEX_PRIVATE_FLAG) ^ (private))
  66 # else
  67 #  define __lll_private_flag(fl, private) \
  68   (__builtin_constant_p (private)                                             \
  69    ? ((private) == 0                                                          \
  70       ? ((fl) | THREAD_GETMEM (THREAD_SELF, header.private_futex))            \
  71       : (fl))                                                                 \
  72    : ((fl) | (((private) ^ FUTEX_PRIVATE_FLAG)                                \
  73               & THREAD_GETMEM (THREAD_SELF, header.private_futex))))
  74 # endif
  75 #endif
  76
  77
  78 #define lll_futex_wait(futexp, val, private) \
  79   lll_futex_timed_wait (futexp, val, NULL, private)
  80
  81 #define lll_futex_timed_wait(futexp, val, timespec, private) \
  82   ({                                                                          \
  83     INTERNAL_SYSCALL_DECL (__err);                                            \
  84     long int __ret;                                                           \
  85     __ret = INTERNAL_SYSCALL (futex, __err, 4, (futexp),                      \
  86                               __lll_private_flag (FUTEX_WAIT, private),       \
  87                               (val), (timespec));                             \
  88     INTERNAL_SYSCALL_ERROR_P (__ret, __err)? -__ret : __ret;                  \
  89   })
  90
  91 #define lll_futex_wake(futexp, nr, private) \
  92   ({                                                                          \
  93     INTERNAL_SYSCALL_DECL (__err);                                            \
  94     long int __ret;                                                           \
  95     __ret = INTERNAL_SYSCALL (futex, __err, 4, (futexp),                      \
  96                               __lll_private_flag (FUTEX_WAKE, private),       \
  97                               (nr), 0);                                       \
  98     INTERNAL_SYSCALL_ERROR_P (__ret, __err)? -__ret : __ret;                  \
  99   })
 100
 101 #define lll_robust_dead(futexv, private) \
 102   do                                                                          \
 103     {                                                                         \
 104       int *__futexp = &(futexv);                                              \
 105       atomic_or (__futexp, FUTEX_OWNER_DIED);                                 \
 106       lll_futex_wake (__futexp, 1, private);                                  \
 107     }                                                                         \
 108   while (0)
 109
 110 /* Returns non-zero if error happened, zero if success.  */
 111 #define lll_futex_requeue(futexp, nr_wake, nr_move, mutex, val, private) \
 112   ({                                                                          \
 113     INTERNAL_SYSCALL_DECL (__err);                                            \
 114     long int __ret;                                                           \
 115     __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp),                      \
 116                               __lll_private_flag (FUTEX_CMP_REQUEUE, private),\
 117                               (nr_wake), (nr_move), (mutex), (val));          \
 118     INTERNAL_SYSCALL_ERROR_P (__ret, __err);                                  \
 119   })
 120
 121 /* Returns non-zero if error happened, zero if success.  */
 122 #define lll_futex_wake_unlock(futexp, nr_wake, nr_wake2, futexp2, private) \
 123   ({                                                                          \
 124     INTERNAL_SYSCALL_DECL (__err);                                            \
 125     long int __ret;                                                           \
 126     __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp),                      \
 127                               __lll_private_flag (FUTEX_WAKE_OP, private),    \
 128                               (nr_wake), (nr_wake2), (futexp2),               \
 129                               FUTEX_OP_CLEAR_WAKE_IF_GT_ONE);                 \
 130     INTERNAL_SYSCALL_ERROR_P (__ret, __err);                                  \
 131   })
 132
 133
 134
 135
 136 static inline int __attribute__((always_inline))
 137 __lll_trylock(int *futex)
 138 {
 139   return atomic_compare_and_exchange_val_acq (futex, 1, 0) != 0;
 140 }
 141 #define lll_trylock(lock)       __lll_trylock (&(lock))
 142
 143
 144 static inline int __attribute__((always_inline))
 145 __lll_cond_trylock(int *futex)
 146 {
 147   return atomic_compare_and_exchange_val_acq (futex, 2, 0) != 0;
 148 }
 149 #define lll_cond_trylock(lock)  __lll_cond_trylock (&(lock))
 150
 151
 152 static inline int __attribute__((always_inline))
 153 __lll_robust_trylock(int *futex, int id)
 154 {
 155   return atomic_compare_and_exchange_val_acq (futex, id, 0) != 0;
 156 }
 157 #define lll_robust_trylock(lock, id) \
 158   __lll_robust_trylock (&(lock), id)
 159
 160 extern void __lll_lock_wait_private (int *futex) attribute_hidden;
 161 extern void __lll_lock_wait (int *futex, int private) attribute_hidden;
 162 extern int __lll_robust_lock_wait (int *futex, int private) attribute_hidden;
 163
 164 static inline void __attribute__((always_inline))
 165 __lll_lock(int *futex, int private)
 166 {
 167   if (atomic_compare_and_exchange_bool_acq (futex, 1, 0) != 0)
 168     {
 169       if (__builtin_constant_p (private) && private == LLL_PRIVATE)
 170         __lll_lock_wait_private (futex);
 171       else
 172         __lll_lock_wait (futex, private);
 173     }
 174 }
 175 #define lll_lock(futex, private) __lll_lock (&(futex), private)
 176
 177
 178 static inline int __attribute__ ((always_inline))
 179 __lll_robust_lock (int *futex, int id, int private)
 180 {
 181   int result = 0;
 182   if (atomic_compare_and_exchange_bool_acq (futex, id, 0) != 0)
 183     result = __lll_robust_lock_wait (futex, private);
 184   return result;
 185 }
 186 #define lll_robust_lock(futex, id, private) \
 187   __lll_robust_lock (&(futex), id, private)
 188
 189
 190 static inline void __attribute__ ((always_inline))
 191 __lll_cond_lock (int *futex, int private)
 192 {
 193   if (atomic_compare_and_exchange_bool_acq (futex, 2, 0) != 0)
 194     __lll_lock_wait (futex, private);
 195 }
 196 #define lll_cond_lock(futex, private) __lll_cond_lock (&(futex), private)
 197
 198
 199 #define lll_robust_cond_lock(futex, id, private) \
 200   __lll_robust_lock (&(futex), (id) | FUTEX_WAITERS, private)
 201
 202
 203 extern int __lll_timedlock_wait (int *futex, const struct timespec *,
 204                                  int private) attribute_hidden;
 205 extern int __lll_robust_timedlock_wait (int *futex, const struct timespec *,
 206                                         int private) attribute_hidden;
 207
 208 static inline int __attribute__ ((always_inline))
 209 __lll_timedlock (int *futex, const struct timespec *abstime, int private)
 210 {
 211   int result = 0;
 212   if (atomic_compare_and_exchange_bool_acq (futex, 1, 0) != 0)
 213     result = __lll_timedlock_wait (futex, abstime, private);
 214   return result;
 215 }
 216 #define lll_timedlock(futex, abstime, private) \
 217   __lll_timedlock (&(futex), abstime, private)
 218
 219
 220 static inline int __attribute__ ((always_inline))
 221 __lll_robust_timedlock (int *futex, const struct timespec *abstime,
 222                         int id, int private)
 223 {
 224   int result = 0;
 225   if (atomic_compare_and_exchange_bool_acq (futex, id, 0) != 0)
 226     result = __lll_robust_timedlock_wait (futex, abstime, private);
 227   return result;
 228 }
 229 #define lll_robust_timedlock(futex, abstime, id, private) \
 230   __lll_robust_timedlock (&(futex), abstime, id, private)
 231
 232
 233 #define __lll_unlock(futex, private) \
 234   (void)                                                        \
 235     ({ int *__futex = (futex);                                  \
 236        int __oldval = atomic_exchange_rel (__futex, 0);         \
 237        if (__builtin_expect (__oldval > 1, 0))                  \
 238          lll_futex_wake (__futex, 1, private);                  \
 239     })
 240 #define lll_unlock(futex, private) __lll_unlock(&(futex), private)
 241
 242
 243 #define __lll_robust_unlock(futex, private) \
 244   (void)                                                        \
 245     ({ int *__futex = (futex);                                  \
 246        int __oldval = atomic_exchange_rel (__futex, 0);         \
 247        if (__builtin_expect (__oldval & FUTEX_WAITERS, 0))      \
 248          lll_futex_wake (__futex, 1, private);                  \
 249     })
 250 #define lll_robust_unlock(futex, private) \
 251   __lll_robust_unlock(&(futex), private)
 252
 253
 254 #define lll_islocked(futex) \
 255   (futex != 0)
 256
 257 /* Initializers for lock.  */
 258 #define LLL_LOCK_INITIALIZER            (0)
 259 #define LLL_LOCK_INITIALIZER_LOCKED     (1)
 260
 261
 262 /* The kernel notifies a process which uses CLONE_CLEARTID via futex
 263    wakeup when the clone terminates.  The memory location contains the
 264    thread ID while the clone is running and is reset to zero
 265    afterwards.  */
 266 #define lll_wait_tid(tid) \
 267   do {                                                  \
 268     __typeof (tid) __tid;                               \
 269     while ((__tid = (tid)) != 0)                        \
 270       lll_futex_wait (&(tid), __tid, LLL_SHARED);       \
 271   } while (0)
 272
 273 extern int __lll_timedwait_tid (int *, const struct timespec *)
 274      attribute_hidden;
 275
 276 #define lll_timedwait_tid(tid, abstime) \
 277   ({                                                    \
 278     int __res = 0;                                      \
 279     if ((tid) != 0)                                     \
 280       __res = __lll_timedwait_tid (&(tid), (abstime));  \
 281     __res;                                              \
 282   })
 283
 284 #endif  /* lowlevellock.h */