threads/cthreads.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 /*
  24  * cthreads.c - by Eric Cooper
  25  *
  26  * Implementation of cthread_fork, cthread_join, cthread_exit, etc.
  27  * HISTORY
  28  * 22-July-93 Blaine Garst
  29  *      fixed association of read_thread info
  30  *      fixed kernel cache set up of cproc info
  31  *
  32  */
  33 #include "pthread_internals.h"
  34 #include <stdlib.h>
  35 #include <sys/queue.h>
  36 #include "cthreads.h"
  37 #include "cthread_internals.h"
  38 /*
  39  * C Threads imports:
  40  */
  41 extern void cproc_init();
  42 extern thread_port_t cproc_create();
  43 extern void mig_init();
  44 extern void _pthread_set_self(pthread_t);
  45
  46 /*
  47  * Mach imports:
  48  */
  49 extern void mig_fork_child();
  50
  51 /*
  52  * C library imports:
  53  */
  54 extern int _setjmp(jmp_buf env);
  55 extern void _longjmp(jmp_buf env, int val);
  56
  57 /*
  58  * Thread status bits.
  59  */
  60 #define T_MAIN          0x1
  61 #define T_RETURNED      0x2
  62 #define T_DETACHED      0x4
  63
  64 #ifdef  CTHREADS_DEBUG
  65 int cthread_debug = FALSE;
  66 #endif  /* CTHREADS_DEBUG */
  67
  68 /*
  69  * Routines for supporting fork() of multi-threaded programs.
  70  */
  71
  72
  73 extern void _malloc_fork_prepare(), _malloc_fork_parent();
  74 extern void _malloc_fork_child();
  75 extern void fork_mach_init();
  76 extern void _cproc_fork_child(), _stack_fork_child();
  77 extern void _lu_fork_child(void);
  78 extern void _pthread_fork_child(pthread_t);
  79 extern void _notify_fork_child(void);
  80
  81 static pthread_t psaved_self = 0;
  82 static pthread_lock_t psaved_self_global_lock = LOCK_INITIALIZER;
  83 static pthread_lock_t pthread_atfork_lock = LOCK_INITIALIZER;
  84 struct pthread_atfork_entry {
  85         TAILQ_ENTRY(pthread_atfork_entry) qentry;
  86         void (*prepare)(void);
  87         void (*parent)(void);
  88         void (*child)(void);
  89 };
  90 static TAILQ_HEAD(pthread_atfork_queue_head, pthread_atfork_entry) pthread_atfork_queue = TAILQ_HEAD_INITIALIZER(pthread_atfork_queue);
  91
  92 int pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void))
  93 {
  94         struct pthread_atfork_entry *e;
  95
  96         e = malloc(sizeof(struct pthread_atfork_entry));
  97         if (e == NULL)
  98                 return (ENOMEM);
  99
 100         e->prepare = prepare;
 101         e->parent = parent;
 102         e->child = child;
 103
 104         _spin_lock(&pthread_atfork_lock);
 105         TAILQ_INSERT_TAIL(&pthread_atfork_queue, e, qentry);
 106         _spin_unlock(&pthread_atfork_lock);
 107
 108         return 0;
 109 }
 110
 111 void _cthread_fork_prepare()
 112 /*
 113  * Prepare cthreads library to fork() a multi-threaded program.  All cthread
 114  * library critical section locks are acquired before a fork() and released
 115  * afterwards to insure no cthread data structure is left in an inconsistent
 116  * state in the child, which comes up with only the forking thread running.
 117  */
 118 {
 119         struct pthread_atfork_entry *e;
 120
 121         _spin_lock(&pthread_atfork_lock);
 122         TAILQ_FOREACH_REVERSE(e, &pthread_atfork_queue, qentry, pthread_atfork_queue_head) {
 123                 if (e->prepare != NULL)
 124                         e->prepare();
 125         }
 126
 127         _spin_lock(&psaved_self_global_lock);
 128         psaved_self = pthread_self();
 129         _spin_lock(&psaved_self->lock);
 130         _malloc_fork_prepare();
 131 }
 132
 133 void _cthread_fork_parent()
 134 /*
 135  * Called in the parent process after a fork syscall.
 136  * Releases locks acquired by cthread_fork_prepare().
 137  */
 138 {
 139         struct pthread_atfork_entry *e;
 140
 141         _malloc_fork_parent();
 142         _spin_unlock(&psaved_self->lock);
 143         _spin_unlock(&psaved_self_global_lock);
 144
 145         TAILQ_FOREACH(e, &pthread_atfork_queue, qentry) {
 146                 if (e->parent != NULL)
 147                         e->parent();
 148         }
 149         _spin_unlock(&pthread_atfork_lock);
 150
 151 }
 152
 153 void _cthread_fork_child()
 154 /*
 155  * Called in the child process after a fork syscall.  Releases locks acquired
 156  * by cthread_fork_prepare().  Deallocates cthread data structures which
 157  * described other threads in our parent.  Makes this thread the main thread.
 158  */
 159 {
 160         pthread_t p = psaved_self;
 161         struct pthread_atfork_entry *e;
 162
 163         _pthread_set_self(p);
 164         _spin_unlock(&psaved_self_global_lock);
 165         mig_fork_child();
 166         _malloc_fork_child();
 167         p->kernel_thread = mach_thread_self();
 168         p->reply_port = mach_reply_port();
 169         p->mutexes = NULL;
 170         p->__cleanup_stack = NULL;
 171         p->death = MACH_PORT_NULL;
 172         p->joiner = NULL;
 173         p->detached |= _PTHREAD_CREATE_PARENT;
 174         _spin_unlock(&p->lock);
 175
 176         fork_mach_init();
 177         _pthread_fork_child(p);
 178
 179         _cproc_fork_child();
 180
 181         _lu_fork_child();
 182
 183         _notify_fork_child();
 184
 185         __is_threaded = 0;
 186
 187         mig_init(1);            /* enable multi-threaded mig interfaces */
 188
 189         TAILQ_FOREACH(e, &pthread_atfork_queue, qentry) {
 190                 if (e->child != NULL)
 191                         e->child();
 192         }
 193         LOCK_INIT(pthread_atfork_lock);
 194
 195 }
 196