sysdeps/nptl/libc-lock.h

   1 /* libc-internal interface for mutex locks.  NPTL version.
   2    Copyright (C) 1996-2020 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 <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _LIBC_LOCK_H
  20 #define _LIBC_LOCK_H 1
  21
  22 #include <pthread.h>
  23 #define __need_NULL
  24 #include <stddef.h>
  25
  26
  27 /* Mutex type.  */
  28 #if defined _LIBC || defined _IO_MTSAFE_IO
  29 # if (!IS_IN (libc) && !IS_IN (libpthread)) || !defined _LIBC
  30 typedef struct { pthread_mutex_t mutex; } __libc_lock_recursive_t;
  31 # else
  32 typedef struct { int lock; int cnt; void *owner; } __libc_lock_recursive_t;
  33 # endif
  34 #else
  35 typedef struct __libc_lock_recursive_opaque__ __libc_lock_recursive_t;
  36 #endif
  37
  38 /* Define a lock variable NAME with storage class CLASS.  The lock must be
  39    initialized with __libc_lock_init before it can be used (or define it
  40    with __libc_lock_define_initialized, below).  Use `extern' for CLASS to
  41    declare a lock defined in another module.  In public structure
  42    definitions you must use a pointer to the lock structure (i.e., NAME
  43    begins with a `*'), because its storage size will not be known outside
  44    of libc.  */
  45 #define __libc_lock_define_recursive(CLASS,NAME) \
  46   CLASS __libc_lock_recursive_t NAME;
  47
  48 /* Define an initialized recursive lock variable NAME with storage
  49    class CLASS.  */
  50 #if defined _LIBC && (IS_IN (libc) || IS_IN (libpthread))
  51 # define __libc_lock_define_initialized_recursive(CLASS, NAME) \
  52   CLASS __libc_lock_recursive_t NAME = _LIBC_LOCK_RECURSIVE_INITIALIZER;
  53 # define _LIBC_LOCK_RECURSIVE_INITIALIZER \
  54   { LLL_LOCK_INITIALIZER, 0, NULL }
  55 #else
  56 # define __libc_lock_define_initialized_recursive(CLASS,NAME) \
  57   CLASS __libc_lock_recursive_t NAME = _LIBC_LOCK_RECURSIVE_INITIALIZER;
  58 # define _LIBC_LOCK_RECURSIVE_INITIALIZER \
  59   {PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP}
  60 #endif
  61
  62 /* Initialize a recursive mutex.  */
  63 #if defined _LIBC && (IS_IN (libc) || IS_IN (libpthread))
  64 # define __libc_lock_init_recursive(NAME) \
  65   ((void) ((NAME) = (__libc_lock_recursive_t) _LIBC_LOCK_RECURSIVE_INITIALIZER))
  66 #else
  67 # define __libc_lock_init_recursive(NAME) \
  68   do {                                                                        \
  69     if (__pthread_mutex_init != NULL)                                         \
  70       {                                                                       \
  71         pthread_mutexattr_t __attr;                                           \
  72         __pthread_mutexattr_init (&__attr);                                   \
  73         __pthread_mutexattr_settype (&__attr, PTHREAD_MUTEX_RECURSIVE_NP);    \
  74         __pthread_mutex_init (&(NAME).mutex, &__attr);                        \
  75         __pthread_mutexattr_destroy (&__attr);                                \
  76       }                                                                       \
  77   } while (0)
  78 #endif
  79
  80 /* Finalize recursive named lock.  */
  81 #if defined _LIBC && (IS_IN (libc) || IS_IN (libpthread))
  82 # define __libc_lock_fini_recursive(NAME) ((void) 0)
  83 #else
  84 # define __libc_lock_fini_recursive(NAME) \
  85   __libc_maybe_call (__pthread_mutex_destroy, (&(NAME).mutex), 0)
  86 #endif
  87
  88 /* Lock the recursive named lock variable.  */
  89 #if defined _LIBC && (IS_IN (libc) || IS_IN (libpthread))
  90 # define __libc_lock_lock_recursive(NAME) \
  91   do {                                                                        \
  92     void *self = THREAD_SELF;                                                 \
  93     if ((NAME).owner != self)                                                 \
  94       {                                                                       \
  95         lll_lock ((NAME).lock, LLL_PRIVATE);                                  \
  96         (NAME).owner = self;                                                  \
  97       }                                                                       \
  98     ++(NAME).cnt;                                                             \
  99   } while (0)
 100 #else
 101 # define __libc_lock_lock_recursive(NAME) \
 102   __libc_maybe_call (__pthread_mutex_lock, (&(NAME).mutex), 0)
 103 #endif
 104
 105 /* Try to lock the recursive named lock variable.  */
 106 #if defined _LIBC && (IS_IN (libc) || IS_IN (libpthread))
 107 # define __libc_lock_trylock_recursive(NAME) \
 108   ({                                                                          \
 109     int result = 0;                                                           \
 110     void *self = THREAD_SELF;                                                 \
 111     if ((NAME).owner != self)                                                 \
 112       {                                                                       \
 113         if (lll_trylock ((NAME).lock) == 0)                                   \
 114           {                                                                   \
 115             (NAME).owner = self;                                              \
 116             (NAME).cnt = 1;                                                   \
 117           }                                                                   \
 118         else                                                                  \
 119           result = EBUSY;                                                     \
 120       }                                                                       \
 121     else                                                                      \
 122       ++(NAME).cnt;                                                           \
 123     result;                                                                   \
 124   })
 125 #else
 126 # define __libc_lock_trylock_recursive(NAME) \
 127   __libc_maybe_call (__pthread_mutex_trylock, (&(NAME).mutex), 0)
 128 #endif
 129
 130 /* Unlock the recursive named lock variable.  */
 131 #if defined _LIBC && (IS_IN (libc) || IS_IN (libpthread))
 132 /* We do no error checking here.  */
 133 # define __libc_lock_unlock_recursive(NAME) \
 134   do {                                                                        \
 135     if (--(NAME).cnt == 0)                                                    \
 136       {                                                                       \
 137         (NAME).owner = NULL;                                                  \
 138         lll_unlock ((NAME).lock, LLL_PRIVATE);                                \
 139       }                                                                       \
 140   } while (0)
 141 #else
 142 # define __libc_lock_unlock_recursive(NAME) \
 143   __libc_maybe_call (__pthread_mutex_unlock, (&(NAME).mutex), 0)
 144 #endif
 145
 146 /* Note that for I/O cleanup handling we are using the old-style
 147    cancel handling.  It does not have to be integrated with C++ since
 148    no C++ code is called in the middle.  The old-style handling is
 149    faster and the support is not going away.  */
 150 extern void _pthread_cleanup_push_defer (struct _pthread_cleanup_buffer *buffer,
 151                                          void (*routine) (void *), void *arg);
 152 extern void _pthread_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer,
 153                                           int execute);
 154
 155 /* Start critical region with cleanup.  */
 156 #define __libc_cleanup_region_start(DOIT, FCT, ARG) \
 157   { struct _pthread_cleanup_buffer _buffer;                                   \
 158     int _avail;                                                               \
 159     if (DOIT) {                                                               \
 160       _avail = PTFAVAIL (_pthread_cleanup_push_defer);                        \
 161       if (_avail) {                                                           \
 162         __libc_ptf_call_always (_pthread_cleanup_push_defer, (&_buffer, FCT,  \
 163                                                               ARG));          \
 164       } else {                                                                \
 165         _buffer.__routine = (FCT);                                            \
 166         _buffer.__arg = (ARG);                                                \
 167       }                                                                       \
 168     } else {                                                                  \
 169       _avail = 0;                                                             \
 170     }
 171
 172 /* End critical region with cleanup.  */
 173 #define __libc_cleanup_region_end(DOIT) \
 174     if (_avail) {                                                             \
 175       __libc_ptf_call_always (_pthread_cleanup_pop_restore, (&_buffer, DOIT));\
 176     } else if (DOIT)                                                          \
 177       _buffer.__routine (_buffer.__arg);                                      \
 178   }
 179
 180
 181 /* Hide the definitions which are only supposed to be used inside libc in
 182    a separate file.  This file is not present in the installation!  */
 183 #ifdef _LIBC
 184 # include "libc-lockP.h"
 185 #endif
 186
 187 #endif  /* libc-lock.h */