sysdeps/unix/sysv/linux/mips/nptl/lowlevellock.h

   1 /* Copyright (C) 2003-2014 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 #define FUTEX_WAIT              0
  29 #define FUTEX_WAKE              1
  30 #define FUTEX_REQUEUE           3
  31 #define FUTEX_CMP_REQUEUE       4
  32 #define FUTEX_WAKE_OP           5
  33 #define FUTEX_OP_CLEAR_WAKE_IF_GT_ONE   ((4 << 24) | 1)
  34 #define FUTEX_LOCK_PI           6
  35 #define FUTEX_UNLOCK_PI         7
  36 #define FUTEX_TRYLOCK_PI        8
  37 #define FUTEX_WAIT_BITSET       9
  38 #define FUTEX_WAKE_BITSET       10
  39 #define FUTEX_WAIT_REQUEUE_PI   11
  40 #define FUTEX_CMP_REQUEUE_PI    12
  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, (long) (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_timed_wait_bitset(futexp, val, timespec, clockbit, private) \
  92   ({                                                                    \
  93     INTERNAL_SYSCALL_DECL (__err);                                      \
  94     long int __ret;                                                     \
  95     int __op = FUTEX_WAIT_BITSET | clockbit;                            \
  96     __ret = INTERNAL_SYSCALL (futex, __err, 6, (long) (futexp),         \
  97                               __lll_private_flag (__op, private),       \
  98                               (val), (timespec), NULL /* Unused.  */,   \
  99                               FUTEX_BITSET_MATCH_ANY);                  \
 100     INTERNAL_SYSCALL_ERROR_P (__ret, __err) ? -__ret : __ret;           \
 101   })
 102
 103 #define lll_futex_wake(futexp, nr, private) \
 104   ({                                                                          \
 105     INTERNAL_SYSCALL_DECL (__err);                                            \
 106     long int __ret;                                                           \
 107     __ret = INTERNAL_SYSCALL (futex, __err, 4, (long) (futexp),               \
 108                               __lll_private_flag (FUTEX_WAKE, private),       \
 109                               (nr), 0);       \
 110     INTERNAL_SYSCALL_ERROR_P (__ret, __err) ? -__ret : __ret;                 \
 111   })
 112
 113 #define lll_robust_dead(futexv, private) \
 114   do                                                                          \
 115     {                                                                         \
 116       int *__futexp = &(futexv);                                              \
 117       atomic_or (__futexp, FUTEX_OWNER_DIED);                                 \
 118       lll_futex_wake (__futexp, 1, private);                                  \
 119     }                                                                         \
 120   while (0)
 121
 122 /* Returns non-zero if error happened, zero if success.  */
 123 #define lll_futex_requeue(futexp, nr_wake, nr_move, mutex, val, private) \
 124   ({                                                                          \
 125     INTERNAL_SYSCALL_DECL (__err);                                            \
 126     long int __ret;                                                           \
 127     __ret = INTERNAL_SYSCALL (futex, __err, 6, (long) (futexp),               \
 128                               __lll_private_flag (FUTEX_CMP_REQUEUE, private),\
 129                               (nr_wake), (nr_move), (mutex), (val));          \
 130     INTERNAL_SYSCALL_ERROR_P (__ret, __err);                                  \
 131   })
 132
 133 /* Returns non-zero if error happened, zero if success.  */
 134 #define lll_futex_wake_unlock(futexp, nr_wake, nr_wake2, futexp2, private) \
 135   ({                                                                          \
 136     INTERNAL_SYSCALL_DECL (__err);                                            \
 137     long int __ret;                                                           \
 138                                                                               \
 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 /* Priority Inheritance support.  */
 147 #define lll_futex_wait_requeue_pi(futexp, val, mutex, private) \
 148   lll_futex_timed_wait_requeue_pi (futexp, val, NULL, 0, mutex, private)
 149
 150 #define lll_futex_timed_wait_requeue_pi(futexp, val, timespec, clockbit,      \
 151                                         mutex, private)                       \
 152   ({                                                                          \
 153     INTERNAL_SYSCALL_DECL (__err);                                            \
 154     long int __ret;                                                           \
 155     int __op = FUTEX_WAIT_REQUEUE_PI | clockbit;                              \
 156                                                                               \
 157     __ret = INTERNAL_SYSCALL (futex, __err, 5, (futexp),                      \
 158                               __lll_private_flag (__op, private),             \
 159                               (val), (timespec), mutex);                      \
 160     INTERNAL_SYSCALL_ERROR_P (__ret, __err) ? -__ret : __ret;                 \
 161   })
 162
 163 #define lll_futex_cmp_requeue_pi(futexp, nr_wake, nr_move, mutex, val, priv)  \
 164   ({                                                                          \
 165     INTERNAL_SYSCALL_DECL (__err);                                            \
 166     long int __ret;                                                           \
 167                                                                               \
 168     __ret = INTERNAL_SYSCALL (futex, __err, 6, (futexp),                      \
 169                               __lll_private_flag (FUTEX_CMP_REQUEUE_PI, priv),\
 170                               (nr_wake), (nr_move), (mutex), (val));          \
 171     INTERNAL_SYSCALL_ERROR_P (__ret, __err);                                  \
 172   })
 173
 174 static inline int __attribute__((always_inline))
 175 __lll_trylock(int *futex)
 176 {
 177   return atomic_compare_and_exchange_val_acq (futex, 1, 0) != 0;
 178 }
 179 #define lll_trylock(lock)       __lll_trylock (&(lock))
 180
 181
 182 static inline int __attribute__((always_inline))
 183 __lll_cond_trylock(int *futex)
 184 {
 185   return atomic_compare_and_exchange_val_acq (futex, 2, 0) != 0;
 186 }
 187 #define lll_cond_trylock(lock)  __lll_cond_trylock (&(lock))
 188
 189
 190 static inline int __attribute__((always_inline))
 191 __lll_robust_trylock(int *futex, int id)
 192 {
 193   return atomic_compare_and_exchange_val_acq (futex, id, 0) != 0;
 194 }
 195 #define lll_robust_trylock(lock, id) \
 196   __lll_robust_trylock (&(lock), id)
 197
 198 extern void __lll_lock_wait_private (int *futex) attribute_hidden;
 199 extern void __lll_lock_wait (int *futex, int private) attribute_hidden;
 200 extern int __lll_robust_lock_wait (int *futex, int private) attribute_hidden;
 201
 202 #define __lll_lock(futex, private)                                            \
 203   ((void) ({                                                                  \
 204     int *__futex = (futex);                                                   \
 205     if (__builtin_expect (atomic_compare_and_exchange_bool_acq (__futex,      \
 206                                                                 1, 0), 0))    \
 207       {                                                                       \
 208         if (__builtin_constant_p (private) && (private) == LLL_PRIVATE)       \
 209           __lll_lock_wait_private (__futex);                                  \
 210         else                                                                  \
 211           __lll_lock_wait (__futex, private);                                 \
 212       }                                                                       \
 213   }))
 214 #define lll_lock(futex, private) __lll_lock (&(futex), private)
 215
 216
 217 #define __lll_robust_lock(futex, id, private)                                 \
 218   ({                                                                          \
 219     int *__futex = (futex);                                                   \
 220     int __val = 0;                                                            \
 221                                                                               \
 222     if (__builtin_expect (atomic_compare_and_exchange_bool_acq (__futex, id,  \
 223                                                                 0), 0))       \
 224       __val = __lll_robust_lock_wait (__futex, private);                      \
 225     __val;                                                                    \
 226   })
 227 #define lll_robust_lock(futex, id, private) \
 228   __lll_robust_lock (&(futex), id, private)
 229
 230
 231 static inline void __attribute__ ((always_inline))
 232 __lll_cond_lock (int *futex, int private)
 233 {
 234   if (atomic_compare_and_exchange_bool_acq (futex, 2, 0) != 0)
 235     __lll_lock_wait (futex, private);
 236 }
 237 #define lll_cond_lock(futex, private) __lll_cond_lock (&(futex), private)
 238
 239
 240 #define lll_robust_cond_lock(futex, id, private) \
 241   __lll_robust_lock (&(futex), (id) | FUTEX_WAITERS, private)
 242
 243
 244 extern int __lll_timedlock_wait (int *futex, const struct timespec *,
 245                                  int private) attribute_hidden;
 246 extern int __lll_robust_timedlock_wait (int *futex, const struct timespec *,
 247                                         int private) attribute_hidden;
 248
 249 static inline int __attribute__ ((always_inline))
 250 __lll_timedlock (int *futex, const struct timespec *abstime, int private)
 251 {
 252   int result = 0;
 253   if (atomic_compare_and_exchange_bool_acq (futex, 1, 0) != 0)
 254     result = __lll_timedlock_wait (futex, abstime, private);
 255   return result;
 256 }
 257 #define lll_timedlock(futex, abstime, private) \
 258   __lll_timedlock (&(futex), abstime, private)
 259
 260
 261 static inline int __attribute__ ((always_inline))
 262 __lll_robust_timedlock (int *futex, const struct timespec *abstime,
 263                         int id, int private)
 264 {
 265   int result = 0;
 266   if (atomic_compare_and_exchange_bool_acq (futex, id, 0) != 0)
 267     result = __lll_robust_timedlock_wait (futex, abstime, private);
 268   return result;
 269 }
 270 #define lll_robust_timedlock(futex, abstime, id, private) \
 271   __lll_robust_timedlock (&(futex), abstime, id, private)
 272
 273
 274 #define __lll_unlock(futex, private)                                          \
 275   ((void) ({                                                                  \
 276     int *__futex = (futex);                                                   \
 277     int __val = atomic_exchange_rel (__futex, 0);                             \
 278                                                                               \
 279     if (__builtin_expect (__val > 1, 0))                                      \
 280       lll_futex_wake (__futex, 1, private);                                   \
 281   }))
 282 #define lll_unlock(futex, private) __lll_unlock(&(futex), private)
 283
 284
 285 #define __lll_robust_unlock(futex, private)                                   \
 286   ((void) ({                                                                  \
 287     int *__futex = (futex);                                                   \
 288     int __val = atomic_exchange_rel (__futex, 0);                             \
 289                                                                               \
 290     if (__builtin_expect (__val & FUTEX_WAITERS, 0))                          \
 291       lll_futex_wake (__futex, 1, private);                                   \
 292   }))
 293 #define lll_robust_unlock(futex, private) \
 294   __lll_robust_unlock(&(futex), private)
 295
 296
 297 #define lll_islocked(futex) \
 298   (futex != 0)
 299
 300
 301 /* Our internal lock implementation is identical to the binary-compatible
 302    mutex implementation. */
 303
 304 /* Initializers for lock.  */
 305 #define LLL_LOCK_INITIALIZER            (0)
 306 #define LLL_LOCK_INITIALIZER_LOCKED     (1)
 307
 308 /* The states of a lock are:
 309     0  -  untaken
 310     1  -  taken by one user
 311    >1  -  taken by more users */
 312
 313 /* The kernel notifies a process which uses CLONE_CHILD_CLEARTID via futex
 314    wakeup when the clone terminates.  The memory location contains the
 315    thread ID while the clone is running and is reset to zero
 316    afterwards.  */
 317 #define lll_wait_tid(tid) \
 318   do {                                                  \
 319     __typeof (tid) __tid;                               \
 320     while ((__tid = (tid)) != 0)                        \
 321       lll_futex_wait (&(tid), __tid, LLL_SHARED);       \
 322   } while (0)
 323
 324 extern int __lll_timedwait_tid (int *, const struct timespec *)
 325      attribute_hidden;
 326
 327 #define lll_timedwait_tid(tid, abstime) \
 328   ({                                                    \
 329     int __res = 0;                                      \
 330     if ((tid) != 0)                                     \
 331       __res = __lll_timedwait_tid (&(tid), (abstime));  \
 332     __res;                                              \
 333   })
 334
 335 /* Implement __libc_lock_lock using exchange_and_add, which expands into
 336    a single instruction on XLP processors.  We enable this for all MIPS
 337    processors as atomic_exchange_and_add_acq and
 338    atomic_compare_and_exchange_acq take the same time to execute.
 339    This is a simplified expansion of ({ lll_lock (NAME, LLL_PRIVATE); 0; }).
 340
 341    Note: __lll_lock_wait_private() resets lock value to '2', which prevents
 342    unbounded increase of the lock value and [with billions of threads]
 343    overflow.  */
 344 #define __libc_lock_lock(NAME)                                          \
 345   ({                                                                    \
 346     int *__futex = &(NAME);                                             \
 347     if (__builtin_expect (atomic_exchange_and_add_acq (__futex, 1), 0)) \
 348       __lll_lock_wait_private (__futex);                                \
 349     0;                                                                  \
 350   })
 351
 352 #ifdef _MIPS_ARCH_XLP
 353 /* The generic version using a single atomic_compare_and_exchange_acq takes
 354    less time for non-XLP processors, so we use below for XLP only.  */
 355 # define __libc_lock_trylock(NAME)                                      \
 356   ({                                                                    \
 357   int *__futex = &(NAME);                                               \
 358   int __result = atomic_exchange_and_add_acq (__futex, 1);              \
 359   /* If __result == 0, we succeeded in acquiring the lock.              \
 360      If __result == 1, we switched the lock to 'contended' state, which \
 361      will cause a [possibly unnecessary] call to lll_futex_wait.  This is \
 362      unlikely, so we accept the possible inefficiency.                  \
 363      If __result >= 2, we need to set the lock to 'contended' state to avoid \
 364      unbounded increase from subsequent trylocks.  */                   \
 365   if (__result >= 2)                                                    \
 366     __result = atomic_exchange_acq (__futex, 2);                        \
 367   __result;                                                             \
 368   })
 369 #endif
 370
 371 #endif  /* lowlevellock.h */