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_bitset(futexp, val, timespec, clockbit, private) \
  82   ({                                                                          \
  83     INTERNAL_SYSCALL_DECL (__err);                                            \
  84     long int __ret;                                                           \
  85     int __op = FUTEX_WAIT_BITSET | clockbit;                                  \
  86                                                                               \
  87     __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp),                      \
  88                               __lll_private_flag (__op, private),             \
  89                               (val), (timespec), NULL /* Unused.  */,         \
  90                               FUTEX_BITSET_MATCH_ANY);                        \
  91     __ret;                                                                    \
  92   })
  93
  94 #define lll_futex_timed_wait(futexp, val, timespec, private) \
  95   ({                                                                          \
  96     INTERNAL_SYSCALL_DECL (__err);                                            \
  97     long int __ret;                                                           \
  98     __ret = INTERNAL_SYSCALL (futex, __err, 4, (futexp),                      \
  99                               __lll_private_flag (FUTEX_WAIT, private),       \
 100                               (val), (timespec));                             \
 101     INTERNAL_SYSCALL_ERROR_P (__ret, __err)? -__ret : __ret;                  \
 102   })
 103
 104 #define lll_futex_wake(futexp, nr, private) \
 105   ({                                                                          \
 106     INTERNAL_SYSCALL_DECL (__err);                                            \
 107     long int __ret;                                                           \
 108     __ret = INTERNAL_SYSCALL (futex, __err, 4, (futexp),                      \
 109                               __lll_private_flag (FUTEX_WAKE, private),       \
 110                               (nr), 0);                                       \
 111     INTERNAL_SYSCALL_ERROR_P (__ret, __err)? -__ret : __ret;                  \
 112   })
 113
 114 #define lll_robust_dead(futexv, private) \
 115   do                                                                          \
 116     {                                                                         \
 117       int *__futexp = &(futexv);                                              \
 118       atomic_or (__futexp, FUTEX_OWNER_DIED);                                 \
 119       lll_futex_wake (__futexp, 1, private);                                  \
 120     }                                                                         \
 121   while (0)
 122
 123 /* Returns non-zero if error happened, zero if success.  */
 124 #define lll_futex_requeue(futexp, nr_wake, nr_move, mutex, val, private) \
 125   ({                                                                          \
 126     INTERNAL_SYSCALL_DECL (__err);                                            \
 127     long int __ret;                                                           \
 128     __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp),                      \
 129                               __lll_private_flag (FUTEX_CMP_REQUEUE, private),\
 130                               (nr_wake), (nr_move), (mutex), (val));          \
 131     INTERNAL_SYSCALL_ERROR_P (__ret, __err);                                  \
 132   })
 133
 134 /* Returns non-zero if error happened, zero if success.  */
 135 #define lll_futex_wake_unlock(futexp, nr_wake, nr_wake2, futexp2, private) \
 136   ({                                                                          \
 137     INTERNAL_SYSCALL_DECL (__err);                                            \
 138     long int __ret;                                                           \
 139     __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp),                      \
 140                               __lll_private_flag (FUTEX_WAKE_OP, private),    \
 141                               (nr_wake), (nr_wake2), (futexp2),               \
 142                               FUTEX_OP_CLEAR_WAKE_IF_GT_ONE);                 \
 143     INTERNAL_SYSCALL_ERROR_P (__ret, __err);                                  \
 144   })
 145
 146
 147
 148
 149 static inline int __attribute__((always_inline))
 150 __lll_trylock(int *futex)
 151 {
 152   return atomic_compare_and_exchange_val_acq (futex, 1, 0) != 0;
 153 }
 154 #define lll_trylock(lock)       __lll_trylock (&(lock))
 155
 156
 157 static inline int __attribute__((always_inline))
 158 __lll_cond_trylock(int *futex)
 159 {
 160   return atomic_compare_and_exchange_val_acq (futex, 2, 0) != 0;
 161 }
 162 #define lll_cond_trylock(lock)  __lll_cond_trylock (&(lock))
 163
 164
 165 static inline int __attribute__((always_inline))
 166 __lll_robust_trylock(int *futex, int id)
 167 {
 168   return atomic_compare_and_exchange_val_acq (futex, id, 0) != 0;
 169 }
 170 #define lll_robust_trylock(lock, id) \
 171   __lll_robust_trylock (&(lock), id)
 172
 173 extern void __lll_lock_wait_private (int *futex) attribute_hidden;
 174 extern void __lll_lock_wait (int *futex, int private) attribute_hidden;
 175 extern int __lll_robust_lock_wait (int *futex, int private) attribute_hidden;
 176
 177 static inline void __attribute__((always_inline))
 178 __lll_lock(int *futex, int private)
 179 {
 180   if (atomic_compare_and_exchange_bool_acq (futex, 1, 0) != 0)
 181     {
 182       if (__builtin_constant_p (private) && private == LLL_PRIVATE)
 183         __lll_lock_wait_private (futex);
 184       else
 185         __lll_lock_wait (futex, private);
 186     }
 187 }
 188 #define lll_lock(futex, private) __lll_lock (&(futex), private)
 189
 190
 191 static inline int __attribute__ ((always_inline))
 192 __lll_robust_lock (int *futex, int id, int private)
 193 {
 194   int result = 0;
 195   if (atomic_compare_and_exchange_bool_acq (futex, id, 0) != 0)
 196     result = __lll_robust_lock_wait (futex, private);
 197   return result;
 198 }
 199 #define lll_robust_lock(futex, id, private) \
 200   __lll_robust_lock (&(futex), id, private)
 201
 202
 203 static inline void __attribute__ ((always_inline))
 204 __lll_cond_lock (int *futex, int private)
 205 {
 206   if (atomic_compare_and_exchange_bool_acq (futex, 2, 0) != 0)
 207     __lll_lock_wait (futex, private);
 208 }
 209 #define lll_cond_lock(futex, private) __lll_cond_lock (&(futex), private)
 210
 211
 212 #define lll_robust_cond_lock(futex, id, private) \
 213   __lll_robust_lock (&(futex), (id) | FUTEX_WAITERS, private)
 214
 215
 216 extern int __lll_timedlock_wait (int *futex, const struct timespec *,
 217                                  int private) attribute_hidden;
 218 extern int __lll_robust_timedlock_wait (int *futex, const struct timespec *,
 219                                         int private) attribute_hidden;
 220
 221 static inline int __attribute__ ((always_inline))
 222 __lll_timedlock (int *futex, const struct timespec *abstime, int private)
 223 {
 224   int result = 0;
 225   if (atomic_compare_and_exchange_bool_acq (futex, 1, 0) != 0)
 226     result = __lll_timedlock_wait (futex, abstime, private);
 227   return result;
 228 }
 229 #define lll_timedlock(futex, abstime, private) \
 230   __lll_timedlock (&(futex), abstime, private)
 231
 232
 233 static inline int __attribute__ ((always_inline))
 234 __lll_robust_timedlock (int *futex, const struct timespec *abstime,
 235                         int id, int private)
 236 {
 237   int result = 0;
 238   if (atomic_compare_and_exchange_bool_acq (futex, id, 0) != 0)
 239     result = __lll_robust_timedlock_wait (futex, abstime, private);
 240   return result;
 241 }
 242 #define lll_robust_timedlock(futex, abstime, id, private) \
 243   __lll_robust_timedlock (&(futex), abstime, id, private)
 244
 245
 246 #define __lll_unlock(futex, private) \
 247   (void)                                                        \
 248     ({ int *__futex = (futex);                                  \
 249        int __oldval = atomic_exchange_rel (__futex, 0);         \
 250        if (__builtin_expect (__oldval > 1, 0))                  \
 251          lll_futex_wake (__futex, 1, private);                  \
 252     })
 253 #define lll_unlock(futex, private) __lll_unlock(&(futex), private)
 254
 255
 256 #define __lll_robust_unlock(futex, private) \
 257   (void)                                                        \
 258     ({ int *__futex = (futex);                                  \
 259        int __oldval = atomic_exchange_rel (__futex, 0);         \
 260        if (__builtin_expect (__oldval & FUTEX_WAITERS, 0))      \
 261          lll_futex_wake (__futex, 1, private);                  \
 262     })
 263 #define lll_robust_unlock(futex, private) \
 264   __lll_robust_unlock(&(futex), private)
 265
 266
 267 #define lll_islocked(futex) \
 268   (futex != 0)
 269
 270 /* Initializers for lock.  */
 271 #define LLL_LOCK_INITIALIZER            (0)
 272 #define LLL_LOCK_INITIALIZER_LOCKED     (1)
 273
 274
 275 /* The kernel notifies a process which uses CLONE_CHILD_CLEARTID via futex
 276    wakeup when the clone terminates.  The memory location contains the
 277    thread ID while the clone is running and is reset to zero
 278    afterwards.  */
 279 #define lll_wait_tid(tid) \
 280   do {                                                  \
 281     __typeof (tid) __tid;                               \
 282     while ((__tid = (tid)) != 0)                        \
 283       lll_futex_wait (&(tid), __tid, LLL_SHARED);       \
 284   } while (0)
 285
 286 extern int __lll_timedwait_tid (int *, const struct timespec *)
 287      attribute_hidden;
 288
 289 #define lll_timedwait_tid(tid, abstime) \
 290   ({                                                    \
 291     int __res = 0;                                      \
 292     if ((tid) != 0)                                     \
 293       __res = __lll_timedwait_tid (&(tid), (abstime));  \
 294     __res;                                              \
 295   })
 296
 297 #endif  /* lowlevellock.h */