sysdeps/nptl/bits/libc-lockP.h

   1 /* Private libc-internal interface for mutex locks.  NPTL version.
   2    Copyright (C) 1996-2015 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If
  17    not, see <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _BITS_LIBC_LOCKP_H
  20 #define _BITS_LIBC_LOCKP_H 1
  21
  22 #include <pthread.h>
  23 #define __need_NULL
  24 #include <stddef.h>
  25
  26
  27 /* Fortunately Linux now has a mean to do locking which is realtime
  28    safe without the aid of the thread library.  We also need no fancy
  29    options like error checking mutexes etc.  We only need simple
  30    locks, maybe recursive.  This can be easily and cheaply implemented
  31    using futexes.  We will use them everywhere except in ld.so since
  32    ld.so might be used on old kernels with a different libc.so.  */
  33 #include <lowlevellock.h>
  34 #include <tls.h>
  35 #include <pthread-functions.h>
  36
  37 #if IS_IN (libpthread)
  38 /* This gets us the declarations of the __pthread_* internal names,
  39    and hidden_proto for them.  */
  40 # include <nptl/pthreadP.h>
  41 #endif
  42
  43 /* Mutex type.  */
  44 #if !IS_IN (libc) && !IS_IN (libpthread)
  45 typedef pthread_mutex_t __libc_lock_t;
  46 #else
  47 typedef int __libc_lock_t;
  48 #endif
  49 typedef struct { pthread_mutex_t mutex; } __rtld_lock_recursive_t;
  50 typedef pthread_rwlock_t __libc_rwlock_t;
  51
  52 /* Type for key to thread-specific data.  */
  53 typedef pthread_key_t __libc_key_t;
  54
  55 /* Define a lock variable NAME with storage class CLASS.  The lock must be
  56    initialized with __libc_lock_init before it can be used (or define it
  57    with __libc_lock_define_initialized, below).  Use `extern' for CLASS to
  58    declare a lock defined in another module.  In public structure
  59    definitions you must use a pointer to the lock structure (i.e., NAME
  60    begins with a `*'), because its storage size will not be known outside
  61    of libc.  */
  62 #define __libc_lock_define(CLASS,NAME) \
  63   CLASS __libc_lock_t NAME;
  64 #define __libc_rwlock_define(CLASS,NAME) \
  65   CLASS __libc_rwlock_t NAME;
  66 #define __rtld_lock_define_recursive(CLASS,NAME) \
  67   CLASS __rtld_lock_recursive_t NAME;
  68
  69 /* Define an initialized lock variable NAME with storage class CLASS.
  70
  71    For the C library we take a deeper look at the initializer.  For
  72    this implementation all fields are initialized to zero.  Therefore
  73    we don't initialize the variable which allows putting it into the
  74    BSS section.  (Except on PA-RISC and other odd architectures, where
  75    initialized locks must be set to one due to the lack of normal
  76    atomic operations.) */
  77
  78 #if IS_IN (libc) || IS_IN (libpthread)
  79 # if LLL_LOCK_INITIALIZER == 0
  80 #  define __libc_lock_define_initialized(CLASS,NAME) \
  81   CLASS __libc_lock_t NAME;
  82 # else
  83 #  define __libc_lock_define_initialized(CLASS,NAME) \
  84   CLASS __libc_lock_t NAME = LLL_LOCK_INITIALIZER;
  85 # endif
  86 #else
  87 # define __libc_lock_define_initialized(CLASS,NAME) \
  88   CLASS __libc_lock_t NAME;
  89 #endif
  90
  91 #define __libc_rwlock_define_initialized(CLASS,NAME) \
  92   CLASS __libc_rwlock_t NAME = PTHREAD_RWLOCK_INITIALIZER;
  93
  94 #define __rtld_lock_define_initialized_recursive(CLASS,NAME) \
  95   CLASS __rtld_lock_recursive_t NAME = _RTLD_LOCK_RECURSIVE_INITIALIZER;
  96 #define _RTLD_LOCK_RECURSIVE_INITIALIZER \
  97   {PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP}
  98
  99 #define __rtld_lock_initialize(NAME) \
 100   (void) ((NAME) = (__rtld_lock_recursive_t) _RTLD_LOCK_RECURSIVE_INITIALIZER)
 101
 102 /* If we check for a weakly referenced symbol and then perform a
 103    normal jump to it te code generated for some platforms in case of
 104    PIC is unnecessarily slow.  What would happen is that the function
 105    is first referenced as data and then it is called indirectly
 106    through the PLT.  We can make this a direct jump.  */
 107 #ifdef __PIC__
 108 # define __libc_maybe_call(FUNC, ARGS, ELSE) \
 109   (__extension__ ({ __typeof (FUNC) *_fn = (FUNC); \
 110                     _fn != NULL ? (*_fn) ARGS : ELSE; }))
 111 #else
 112 # define __libc_maybe_call(FUNC, ARGS, ELSE) \
 113   (FUNC != NULL ? FUNC ARGS : ELSE)
 114 #endif
 115
 116 /* Call thread functions through the function pointer table.  */
 117 #if defined SHARED && IS_IN (libc)
 118 # define PTFAVAIL(NAME) __libc_pthread_functions_init
 119 # define __libc_ptf_call(FUNC, ARGS, ELSE) \
 120   (__libc_pthread_functions_init ? PTHFCT_CALL (ptr_##FUNC, ARGS) : ELSE)
 121 # define __libc_ptf_call_always(FUNC, ARGS) \
 122   PTHFCT_CALL (ptr_##FUNC, ARGS)
 123 #elif IS_IN (libpthread)
 124 # define PTFAVAIL(NAME) 1
 125 # define __libc_ptf_call(FUNC, ARGS, ELSE) \
 126   FUNC ARGS
 127 # define __libc_ptf_call_always(FUNC, ARGS) \
 128   FUNC ARGS
 129 #else
 130 # define PTFAVAIL(NAME) (NAME != NULL)
 131 # define __libc_ptf_call(FUNC, ARGS, ELSE) \
 132   __libc_maybe_call (FUNC, ARGS, ELSE)
 133 # define __libc_ptf_call_always(FUNC, ARGS) \
 134   FUNC ARGS
 135 #endif
 136
 137
 138 /* Initialize the named lock variable, leaving it in a consistent, unlocked
 139    state.  */
 140 #if IS_IN (libc) || IS_IN (libpthread)
 141 # define __libc_lock_init(NAME) \
 142   ((void) ((NAME) = LLL_LOCK_INITIALIZER))
 143 #else
 144 # define __libc_lock_init(NAME) \
 145   __libc_maybe_call (__pthread_mutex_init, (&(NAME), NULL), 0)
 146 #endif
 147 #if defined SHARED && IS_IN (libc)
 148 /* ((NAME) = (__libc_rwlock_t) PTHREAD_RWLOCK_INITIALIZER) is inefficient.  */
 149 # define __libc_rwlock_init(NAME) \
 150   ((void) __builtin_memset (&(NAME), '\0', sizeof (NAME)))
 151 #else
 152 # define __libc_rwlock_init(NAME) \
 153   __libc_maybe_call (__pthread_rwlock_init, (&(NAME), NULL), 0)
 154 #endif
 155
 156 /* Finalize the named lock variable, which must be locked.  It cannot be
 157    used again until __libc_lock_init is called again on it.  This must be
 158    called on a lock variable before the containing storage is reused.  */
 159 #if IS_IN (libc) || IS_IN (libpthread)
 160 # define __libc_lock_fini(NAME) ((void) 0)
 161 #else
 162 # define __libc_lock_fini(NAME) \
 163   __libc_maybe_call (__pthread_mutex_destroy, (&(NAME)), 0)
 164 #endif
 165 #if defined SHARED && IS_IN (libc)
 166 # define __libc_rwlock_fini(NAME) ((void) 0)
 167 #else
 168 # define __libc_rwlock_fini(NAME) \
 169   __libc_maybe_call (__pthread_rwlock_destroy, (&(NAME)), 0)
 170 #endif
 171
 172 /* Lock the named lock variable.  */
 173 #if IS_IN (libc) || IS_IN (libpthread)
 174 # ifndef __libc_lock_lock
 175 #  define __libc_lock_lock(NAME) \
 176   ({ lll_lock (NAME, LLL_PRIVATE); 0; })
 177 # endif
 178 #else
 179 # undef __libc_lock_lock
 180 # define __libc_lock_lock(NAME) \
 181   __libc_maybe_call (__pthread_mutex_lock, (&(NAME)), 0)
 182 #endif
 183 #define __libc_rwlock_rdlock(NAME) \
 184   __libc_ptf_call (__pthread_rwlock_rdlock, (&(NAME)), 0)
 185 #define __libc_rwlock_wrlock(NAME) \
 186   __libc_ptf_call (__pthread_rwlock_wrlock, (&(NAME)), 0)
 187
 188 /* Try to lock the named lock variable.  */
 189 #if IS_IN (libc) || IS_IN (libpthread)
 190 # ifndef __libc_lock_trylock
 191 #  define __libc_lock_trylock(NAME) \
 192   lll_trylock (NAME)
 193 # endif
 194 #else
 195 # undef __libc_lock_trylock
 196 # define __libc_lock_trylock(NAME) \
 197   __libc_maybe_call (__pthread_mutex_trylock, (&(NAME)), 0)
 198 #endif
 199 #define __libc_rwlock_tryrdlock(NAME) \
 200   __libc_maybe_call (__pthread_rwlock_tryrdlock, (&(NAME)), 0)
 201 #define __libc_rwlock_trywrlock(NAME) \
 202   __libc_maybe_call (__pthread_rwlock_trywrlock, (&(NAME)), 0)
 203
 204 #define __rtld_lock_trylock_recursive(NAME) \
 205   __libc_maybe_call (__pthread_mutex_trylock, (&(NAME).mutex), 0)
 206
 207 /* Unlock the named lock variable.  */
 208 #if IS_IN (libc) || IS_IN (libpthread)
 209 # define __libc_lock_unlock(NAME) \
 210   lll_unlock (NAME, LLL_PRIVATE)
 211 #else
 212 # define __libc_lock_unlock(NAME) \
 213   __libc_maybe_call (__pthread_mutex_unlock, (&(NAME)), 0)
 214 #endif
 215 #define __libc_rwlock_unlock(NAME) \
 216   __libc_ptf_call (__pthread_rwlock_unlock, (&(NAME)), 0)
 217
 218 #ifdef SHARED
 219 # define __rtld_lock_default_lock_recursive(lock) \
 220   ++((pthread_mutex_t *)(lock))->__data.__count;
 221
 222 # define __rtld_lock_default_unlock_recursive(lock) \
 223   --((pthread_mutex_t *)(lock))->__data.__count;
 224
 225 # define __rtld_lock_lock_recursive(NAME) \
 226   GL(dl_rtld_lock_recursive) (&(NAME).mutex)
 227
 228 # define __rtld_lock_unlock_recursive(NAME) \
 229   GL(dl_rtld_unlock_recursive) (&(NAME).mutex)
 230 #else
 231 # define __rtld_lock_lock_recursive(NAME) \
 232   __libc_maybe_call (__pthread_mutex_lock, (&(NAME).mutex), 0)
 233
 234 # define __rtld_lock_unlock_recursive(NAME) \
 235   __libc_maybe_call (__pthread_mutex_unlock, (&(NAME).mutex), 0)
 236 #endif
 237
 238 /* Define once control variable.  */
 239 #if PTHREAD_ONCE_INIT == 0
 240 /* Special case for static variables where we can avoid the initialization
 241    if it is zero.  */
 242 # define __libc_once_define(CLASS, NAME) \
 243   CLASS pthread_once_t NAME
 244 #else
 245 # define __libc_once_define(CLASS, NAME) \
 246   CLASS pthread_once_t NAME = PTHREAD_ONCE_INIT
 247 #endif
 248
 249 /* Call handler iff the first call.  */
 250 #define __libc_once(ONCE_CONTROL, INIT_FUNCTION) \
 251   do {                                                                        \
 252     if (PTFAVAIL (__pthread_once))                                            \
 253       __libc_ptf_call_always (__pthread_once, (&(ONCE_CONTROL),               \
 254                                                INIT_FUNCTION));               \
 255     else if ((ONCE_CONTROL) == PTHREAD_ONCE_INIT) {                           \
 256       INIT_FUNCTION ();                                                       \
 257       (ONCE_CONTROL) |= 2;                                                    \
 258     }                                                                         \
 259   } while (0)
 260
 261 /* Get once control variable.  */
 262 #define __libc_once_get(ONCE_CONTROL)   ((ONCE_CONTROL) != PTHREAD_ONCE_INIT)
 263
 264 /* Note that for I/O cleanup handling we are using the old-style
 265    cancel handling.  It does not have to be integrated with C++ snce
 266    no C++ code is called in the middle.  The old-style handling is
 267    faster and the support is not going away.  */
 268 extern void _pthread_cleanup_push (struct _pthread_cleanup_buffer *buffer,
 269                                    void (*routine) (void *), void *arg);
 270 extern void _pthread_cleanup_pop (struct _pthread_cleanup_buffer *buffer,
 271                                   int execute);
 272 extern void _pthread_cleanup_push_defer (struct _pthread_cleanup_buffer *buffer,
 273                                          void (*routine) (void *), void *arg);
 274 extern void _pthread_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer,
 275                                           int execute);
 276
 277 /* Sometimes we have to exit the block in the middle.  */
 278 #define __libc_cleanup_end(DOIT) \
 279     if (_avail) {                                                             \
 280       __libc_ptf_call_always (_pthread_cleanup_pop_restore, (&_buffer, DOIT));\
 281     } else if (DOIT)                                                          \
 282       _buffer.__routine (_buffer.__arg)
 283
 284
 285 /* Normal cleanup handling, based on C cleanup attribute.  */
 286 __extern_inline void
 287 __libc_cleanup_routine (struct __pthread_cleanup_frame *f)
 288 {
 289   if (f->__do_it)
 290     f->__cancel_routine (f->__cancel_arg);
 291 }
 292
 293 #define __libc_cleanup_push(fct, arg) \
 294   do {                                                                        \
 295     struct __pthread_cleanup_frame __clframe                                  \
 296       __attribute__ ((__cleanup__ (__libc_cleanup_routine)))                  \
 297       = { .__cancel_routine = (fct), .__cancel_arg = (arg),                   \
 298           .__do_it = 1 };
 299
 300 #define __libc_cleanup_pop(execute) \
 301     __clframe.__do_it = (execute);                                            \
 302   } while (0)
 303
 304
 305 /* Create thread-specific key.  */
 306 #define __libc_key_create(KEY, DESTRUCTOR) \
 307   __libc_ptf_call (__pthread_key_create, (KEY, DESTRUCTOR), 1)
 308
 309 /* Get thread-specific data.  */
 310 #define __libc_getspecific(KEY) \
 311   __libc_ptf_call (__pthread_getspecific, (KEY), NULL)
 312
 313 /* Set thread-specific data.  */
 314 #define __libc_setspecific(KEY, VALUE) \
 315   __libc_ptf_call (__pthread_setspecific, (KEY, VALUE), 0)
 316
 317
 318 /* Register handlers to execute before and after `fork'.  Note that the
 319    last parameter is NULL.  The handlers registered by the libc are
 320    never removed so this is OK.  */
 321 #define __libc_atfork(PREPARE, PARENT, CHILD) \
 322   __register_atfork (PREPARE, PARENT, CHILD, NULL)
 323 extern int __register_atfork (void (*__prepare) (void),
 324                               void (*__parent) (void),
 325                               void (*__child) (void),
 326                               void *__dso_handle);
 327
 328 /* Functions that are used by this file and are internal to the GNU C
 329    library.  */
 330
 331 extern int __pthread_mutex_init (pthread_mutex_t *__mutex,
 332                                  const pthread_mutexattr_t *__mutex_attr);
 333
 334 extern int __pthread_mutex_destroy (pthread_mutex_t *__mutex);
 335
 336 extern int __pthread_mutex_trylock (pthread_mutex_t *__mutex);
 337
 338 extern int __pthread_mutex_lock (pthread_mutex_t *__mutex);
 339
 340 extern int __pthread_mutex_unlock (pthread_mutex_t *__mutex);
 341
 342 extern int __pthread_mutexattr_init (pthread_mutexattr_t *__attr);
 343
 344 extern int __pthread_mutexattr_destroy (pthread_mutexattr_t *__attr);
 345
 346 extern int __pthread_mutexattr_settype (pthread_mutexattr_t *__attr,
 347                                         int __kind);
 348
 349 extern int __pthread_rwlock_init (pthread_rwlock_t *__rwlock,
 350                                   const pthread_rwlockattr_t *__attr);
 351
 352 extern int __pthread_rwlock_destroy (pthread_rwlock_t *__rwlock);
 353
 354 extern int __pthread_rwlock_rdlock (pthread_rwlock_t *__rwlock);
 355
 356 extern int __pthread_rwlock_tryrdlock (pthread_rwlock_t *__rwlock);
 357
 358 extern int __pthread_rwlock_wrlock (pthread_rwlock_t *__rwlock);
 359
 360 extern int __pthread_rwlock_trywrlock (pthread_rwlock_t *__rwlock);
 361
 362 extern int __pthread_rwlock_unlock (pthread_rwlock_t *__rwlock);
 363
 364 extern int __pthread_key_create (pthread_key_t *__key,
 365                                  void (*__destr_function) (void *));
 366
 367 extern int __pthread_setspecific (pthread_key_t __key,
 368                                   const void *__pointer);
 369
 370 extern void *__pthread_getspecific (pthread_key_t __key);
 371
 372 extern int __pthread_once (pthread_once_t *__once_control,
 373                            void (*__init_routine) (void));
 374
 375 extern int __pthread_atfork (void (*__prepare) (void),
 376                              void (*__parent) (void),
 377                              void (*__child) (void));
 378
 379
 380
 381 /* Make the pthread functions weak so that we can elide them from
 382    single-threaded processes.  */
 383 #ifndef __NO_WEAK_PTHREAD_ALIASES
 384 # ifdef weak_extern
 385 weak_extern (__pthread_mutex_init)
 386 weak_extern (__pthread_mutex_destroy)
 387 weak_extern (__pthread_mutex_lock)
 388 weak_extern (__pthread_mutex_trylock)
 389 weak_extern (__pthread_mutex_unlock)
 390 weak_extern (__pthread_mutexattr_init)
 391 weak_extern (__pthread_mutexattr_destroy)
 392 weak_extern (__pthread_mutexattr_settype)
 393 weak_extern (__pthread_rwlock_init)
 394 weak_extern (__pthread_rwlock_destroy)
 395 weak_extern (__pthread_rwlock_rdlock)
 396 weak_extern (__pthread_rwlock_tryrdlock)
 397 weak_extern (__pthread_rwlock_wrlock)
 398 weak_extern (__pthread_rwlock_trywrlock)
 399 weak_extern (__pthread_rwlock_unlock)
 400 weak_extern (__pthread_key_create)
 401 weak_extern (__pthread_setspecific)
 402 weak_extern (__pthread_getspecific)
 403 weak_extern (__pthread_once)
 404 weak_extern (__pthread_initialize)
 405 weak_extern (__pthread_atfork)
 406 weak_extern (_pthread_cleanup_push_defer)
 407 weak_extern (_pthread_cleanup_pop_restore)
 408 weak_extern (pthread_setcancelstate)
 409 # else
 410 #  pragma weak __pthread_mutex_init
 411 #  pragma weak __pthread_mutex_destroy
 412 #  pragma weak __pthread_mutex_lock
 413 #  pragma weak __pthread_mutex_trylock
 414 #  pragma weak __pthread_mutex_unlock
 415 #  pragma weak __pthread_mutexattr_init
 416 #  pragma weak __pthread_mutexattr_destroy
 417 #  pragma weak __pthread_mutexattr_settype
 418 #  pragma weak __pthread_rwlock_destroy
 419 #  pragma weak __pthread_rwlock_rdlock
 420 #  pragma weak __pthread_rwlock_tryrdlock
 421 #  pragma weak __pthread_rwlock_wrlock
 422 #  pragma weak __pthread_rwlock_trywrlock
 423 #  pragma weak __pthread_rwlock_unlock
 424 #  pragma weak __pthread_key_create
 425 #  pragma weak __pthread_setspecific
 426 #  pragma weak __pthread_getspecific
 427 #  pragma weak __pthread_once
 428 #  pragma weak __pthread_initialize
 429 #  pragma weak __pthread_atfork
 430 #  pragma weak _pthread_cleanup_push_defer
 431 #  pragma weak _pthread_cleanup_pop_restore
 432 #  pragma weak pthread_setcancelstate
 433 # endif
 434 #endif
 435
 436 #endif  /* bits/libc-lockP.h */