linuxthreads/specific.c

   1 /* Linuxthreads - a simple clone()-based implementation of Posix        */
   2 /* threads for Linux.                                                   */
   3 /* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr)              */
   4 /*                                                                      */
   5 /* This program is free software; you can redistribute it and/or        */
   6 /* modify it under the terms of the GNU Library General Public License  */
   7 /* as published by the Free Software Foundation; either version 2       */
   8 /* of the License, or (at your option) any later version.               */
   9 /*                                                                      */
  10 /* This program 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        */
  13 /* GNU Library General Public License for more details.                 */
  14
  15 /* Thread-specific data */
  16
  17 #include <errno.h>
  18 #include <stddef.h>
  19 #include <stdlib.h>
  20 #include "pthread.h"
  21 #include "internals.h"
  22 #include "spinlock.h"
  23 #include "restart.h"
  24 #include <bits/libc-lock.h>
  25
  26
  27 /* Table of keys. */
  28
  29 static struct pthread_key_struct pthread_keys[PTHREAD_KEYS_MAX] =
  30   { { 0, NULL } };
  31
  32 /* For debugging purposes put the maximum number of keys in a variable.  */
  33 const int __linuxthreads_pthread_keys_max = PTHREAD_KEYS_MAX;
  34 const int __linuxthreads_pthread_key_2ndlevel_size = PTHREAD_KEY_2NDLEVEL_SIZE;
  35
  36 /* Mutex to protect access to pthread_keys */
  37
  38 static pthread_mutex_t pthread_keys_mutex = PTHREAD_MUTEX_INITIALIZER;
  39
  40 /* Create a new key */
  41
  42 int __pthread_key_create(pthread_key_t * key, destr_function destr)
  43 {
  44   int i;
  45
  46   pthread_mutex_lock(&pthread_keys_mutex);
  47   for (i = 0; i < PTHREAD_KEYS_MAX; i++) {
  48     if (! pthread_keys[i].in_use) {
  49       /* Mark key in use */
  50       pthread_keys[i].in_use = 1;
  51       pthread_keys[i].destr = destr;
  52       pthread_mutex_unlock(&pthread_keys_mutex);
  53       *key = i;
  54       return 0;
  55     }
  56   }
  57   pthread_mutex_unlock(&pthread_keys_mutex);
  58   return EAGAIN;
  59 }
  60 strong_alias (__pthread_key_create, pthread_key_create)
  61
  62 /* Reset deleted key's value to NULL in each live thread.
  63  * NOTE: this executes in the context of the thread manager! */
  64
  65 struct pthread_key_delete_helper_args {
  66   /* Damn, we need lexical closures in C! ;) */
  67   unsigned int idx1st, idx2nd;
  68   pthread_descr self;
  69 };
  70
  71 static void pthread_key_delete_helper(void *arg, pthread_descr th)
  72 {
  73   struct pthread_key_delete_helper_args *args = arg;
  74   unsigned int idx1st = args->idx1st;
  75   unsigned int idx2nd = args->idx2nd;
  76   pthread_descr self = args->self;
  77
  78   if (self == 0)
  79     self = args->self = thread_self();
  80
  81   if (!th->p_terminated) {
  82     /* pthread_exit() may try to free th->p_specific[idx1st] concurrently. */
  83     __pthread_lock(THREAD_GETMEM(th, p_lock), self);
  84     if (th->p_specific[idx1st] != NULL)
  85       th->p_specific[idx1st][idx2nd] = NULL;
  86     __pthread_unlock(THREAD_GETMEM(th, p_lock));
  87   }
  88 }
  89
  90 /* Delete a key */
  91 int pthread_key_delete(pthread_key_t key)
  92 {
  93   pthread_descr self = thread_self();
  94
  95   pthread_mutex_lock(&pthread_keys_mutex);
  96   if (key >= PTHREAD_KEYS_MAX || !pthread_keys[key].in_use) {
  97     pthread_mutex_unlock(&pthread_keys_mutex);
  98     return EINVAL;
  99   }
 100   pthread_keys[key].in_use = 0;
 101   pthread_keys[key].destr = NULL;
 102
 103   /* Set the value of the key to NULL in all running threads, so
 104      that if the key is reallocated later by pthread_key_create, its
 105      associated values will be NULL in all threads.
 106
 107      Do nothing if no threads have been created yet.  */
 108
 109   if (__pthread_manager_request != -1)
 110     {
 111       struct pthread_key_delete_helper_args args;
 112       struct pthread_request request;
 113
 114       args.idx1st = key / PTHREAD_KEY_2NDLEVEL_SIZE;
 115       args.idx2nd = key % PTHREAD_KEY_2NDLEVEL_SIZE;
 116       args.self = 0;
 117
 118       request.req_thread = self;
 119       request.req_kind = REQ_FOR_EACH_THREAD;
 120       request.req_args.for_each.arg = &args;
 121       request.req_args.for_each.fn = pthread_key_delete_helper;
 122
 123       TEMP_FAILURE_RETRY(__libc_write(__pthread_manager_request,
 124                                       (char *) &request, sizeof(request)));
 125       suspend(self);
 126     }
 127
 128   pthread_mutex_unlock(&pthread_keys_mutex);
 129   return 0;
 130 }
 131
 132 /* Set the value of a key */
 133
 134 int __pthread_setspecific(pthread_key_t key, const void * pointer)
 135 {
 136   pthread_descr self = thread_self();
 137   unsigned int idx1st, idx2nd;
 138
 139   if (key >= PTHREAD_KEYS_MAX || !pthread_keys[key].in_use)
 140     return EINVAL;
 141   idx1st = key / PTHREAD_KEY_2NDLEVEL_SIZE;
 142   idx2nd = key % PTHREAD_KEY_2NDLEVEL_SIZE;
 143   if (THREAD_GETMEM_NC(self, p_specific[idx1st]) == NULL) {
 144     void *newp = calloc(PTHREAD_KEY_2NDLEVEL_SIZE, sizeof (void *));
 145     if (newp == NULL)
 146       return ENOMEM;
 147     THREAD_SETMEM_NC(self, p_specific[idx1st], newp);
 148   }
 149   THREAD_GETMEM_NC(self, p_specific[idx1st])[idx2nd] = (void *) pointer;
 150   return 0;
 151 }
 152 strong_alias (__pthread_setspecific, pthread_setspecific)
 153
 154 /* Get the value of a key */
 155
 156 void * __pthread_getspecific(pthread_key_t key)
 157 {
 158   pthread_descr self = thread_self();
 159   unsigned int idx1st, idx2nd;
 160
 161   if (key >= PTHREAD_KEYS_MAX)
 162     return NULL;
 163   idx1st = key / PTHREAD_KEY_2NDLEVEL_SIZE;
 164   idx2nd = key % PTHREAD_KEY_2NDLEVEL_SIZE;
 165   if (THREAD_GETMEM_NC(self, p_specific[idx1st]) == NULL
 166       || !pthread_keys[key].in_use)
 167     return NULL;
 168   return THREAD_GETMEM_NC(self, p_specific[idx1st])[idx2nd];
 169 }
 170 strong_alias (__pthread_getspecific, pthread_getspecific)
 171
 172 /* Call the destruction routines on all keys */
 173
 174 void __pthread_destroy_specifics()
 175 {
 176   pthread_descr self = thread_self();
 177   int i, j, round, found_nonzero;
 178   destr_function destr;
 179   void * data;
 180
 181   for (round = 0, found_nonzero = 1;
 182        found_nonzero && round < PTHREAD_DESTRUCTOR_ITERATIONS;
 183        round++) {
 184     found_nonzero = 0;
 185     for (i = 0; i < PTHREAD_KEY_1STLEVEL_SIZE; i++)
 186       if (THREAD_GETMEM_NC(self, p_specific[i]) != NULL)
 187         for (j = 0; j < PTHREAD_KEY_2NDLEVEL_SIZE; j++) {
 188           destr = pthread_keys[i * PTHREAD_KEY_2NDLEVEL_SIZE + j].destr;
 189           data = THREAD_GETMEM_NC(self, p_specific[i])[j];
 190           if (destr != NULL && data != NULL) {
 191             THREAD_GETMEM_NC(self, p_specific[i])[j] = NULL;
 192             destr(data);
 193             found_nonzero = 1;
 194           }
 195         }
 196   }
 197   __pthread_lock(THREAD_GETMEM(self, p_lock), self);
 198   for (i = 0; i < PTHREAD_KEY_1STLEVEL_SIZE; i++) {
 199     if (THREAD_GETMEM_NC(self, p_specific[i]) != NULL) {
 200       free(THREAD_GETMEM_NC(self, p_specific[i]));
 201       THREAD_SETMEM_NC(self, p_specific[i], NULL);
 202     }
 203   }
 204   __pthread_unlock(THREAD_GETMEM(self, p_lock));
 205 }
 206
 207 /* Thread-specific data for libc. */
 208
 209 static int
 210 libc_internal_tsd_set(enum __libc_tsd_key_t key, const void * pointer)
 211 {
 212   pthread_descr self = thread_self();
 213
 214   THREAD_SETMEM_NC(self, p_libc_specific[key], (void *) pointer);
 215   return 0;
 216 }
 217 int (*__libc_internal_tsd_set)(enum __libc_tsd_key_t key, const void * pointer)
 218      = libc_internal_tsd_set;
 219
 220 static void *
 221 libc_internal_tsd_get(enum __libc_tsd_key_t key)
 222 {
 223   pthread_descr self = thread_self();
 224
 225   return THREAD_GETMEM_NC(self, p_libc_specific[key]);
 226 }
 227 void * (*__libc_internal_tsd_get)(enum __libc_tsd_key_t key)
 228      = libc_internal_tsd_get;