lib/libc_r/uthread/uthread_fork.c

   1 /*
   2  * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by John Birrell.
  16  * 4. Neither the name of the author nor the names of any co-contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * $FreeBSD: src/lib/libc_r/uthread/uthread_fork.c,v 1.19.2.7 2002/10/22 14:44:03 fjoe Exp $
  33  */
  34
  35 #include <sys/syscall.h>
  36 #include <errno.h>
  37 #include <string.h>
  38 #include <stdlib.h>
  39 #include <unistd.h>
  40 #include <fcntl.h>
  41 #include <pthread.h>
  42 #include "pthread_private.h"
  43
  44 pid_t
  45 _fork(void)
  46 {
  47         struct pthread  *curthread = _get_curthread();
  48         struct pthread_atfork *af;
  49         int             i;
  50         pid_t           ret;
  51         pthread_t       pthread;
  52         pthread_t       pthread_save;
  53
  54         /*
  55          * Defer signals to protect the scheduling queues from access
  56          * by the signal handler:
  57          */
  58         _thread_kern_sig_defer();
  59
  60         _pthread_mutex_lock(&_atfork_mutex);
  61
  62         /* Run down atfork prepare handlers. */
  63         TAILQ_FOREACH_REVERSE(af, &_atfork_list, atfork_head, qe) {
  64                 if (af->prepare != NULL)
  65                         af->prepare();
  66         }
  67
  68         /* Fork a new process: */
  69         if ((ret = __syscall(SYS_fork)) != 0) {
  70                 /* Run down atfork parent handlers. */
  71                 TAILQ_FOREACH(af, &_atfork_list, qe) {
  72                         if (af->parent != NULL)
  73                                 af->parent();
  74                 }
  75                 _pthread_mutex_unlock(&_atfork_mutex);
  76         } else {
  77                 /* Close the pthread kernel pipe: */
  78                 __sys_close(_thread_kern_pipe[0]);
  79                 __sys_close(_thread_kern_pipe[1]);
  80
  81                 /* Reset signals pending for the running thread: */
  82                 sigemptyset(&curthread->sigpend);
  83
  84                 _thread_mksigpipe();
  85
  86                 /* Reinitialize the GC mutex: */
  87                 if (_mutex_reinit(&_gc_mutex) != 0) {
  88                         /* Abort this application: */
  89                         PANIC("Cannot initialize GC mutex for forked process");
  90                 }
  91                 /* Reinitialize the GC condition variable: */
  92                 else if (_cond_reinit(&_gc_cond) != 0) {
  93                         /* Abort this application: */
  94                         PANIC("Cannot initialize GC condvar for forked process");
  95                 }
  96                 /* Initialize the ready queue: */
  97                 else if (_pq_init(&_readyq) != 0) {
  98                         /* Abort this application: */
  99                         PANIC("Cannot initialize priority ready queue.");
 100                 } else {
 101                         /*
 102                          * Enter a loop to remove all threads other than
 103                          * the running thread from the thread list:
 104                          */
 105                         pthread = TAILQ_FIRST(&_thread_list);
 106                         while (pthread != NULL) {
 107                                 /* Save the thread to be freed: */
 108                                 pthread_save = pthread;
 109
 110                                 /*
 111                                  * Advance to the next thread before
 112                                  * destroying the current thread:
 113                                  */
 114                                 pthread = TAILQ_NEXT(pthread, tle);
 115
 116                                 /* Make sure this isn't the running thread: */
 117                                 if (pthread_save != curthread) {
 118                                         /* Remove this thread from the list: */
 119                                         TAILQ_REMOVE(&_thread_list,
 120                                             pthread_save, tle);
 121
 122                                         if (pthread_save->attr.stackaddr_attr ==
 123                                             NULL && pthread_save->stack != NULL) {
 124                                                 if (pthread_save->attr.stacksize_attr
 125                                                     == PTHREAD_STACK_DEFAULT) {
 126                                                         /*
 127                                                          * Default-size stack.
 128                                                          * Cache it:
 129                                                          */
 130                                                         struct stack    *spare_stack;
 131
 132                                                         spare_stack
 133                                                             = (pthread_save->stack
 134                                                             + PTHREAD_STACK_DEFAULT
 135                                                             - sizeof(struct stack));
 136                                                         SLIST_INSERT_HEAD(&_stackq,
 137                                                             spare_stack, qe);
 138                                                 } else
 139                                                         /*
 140                                                          * Free the stack of
 141                                                          * the dead thread:
 142                                                          */
 143                                                         free(pthread_save->stack);
 144                                         }
 145
 146                                         if (pthread_save->specific_data != NULL)
 147                                                 free(pthread_save->specific_data);
 148
 149                                         if (pthread_save->poll_data.fds != NULL)
 150                                                 free(pthread_save->poll_data.fds);
 151
 152                                         _rtld_free_tls(pthread_save->tcb);
 153                                         free(pthread_save);
 154                                 }
 155                         }
 156
 157                         /* Treat the current thread as the initial thread: */
 158                         _thread_initial = curthread;
 159
 160                         /* Re-init the dead thread list: */
 161                         TAILQ_INIT(&_dead_list);
 162
 163                         /* Re-init the waiting and work queues. */
 164                         TAILQ_INIT(&_waitingq);
 165                         TAILQ_INIT(&_workq);
 166
 167                         /* Re-init the threads mutex queue: */
 168                         TAILQ_INIT(&curthread->mutexq);
 169
 170                         /* No spinlocks yet: */
 171                         _spinblock_count = 0;
 172
 173                         /* Don't queue signals yet: */
 174                         _queue_signals = 0;
 175
 176                         /* Initialize the scheduling switch hook routine: */
 177                         _sched_switch_hook = NULL;
 178
 179                         /* Clear out any locks in the file descriptor table: */
 180                         for (i = 0; i < _thread_dtablesize; i++) {
 181                                 if (_thread_fd_table[i] != NULL) {
 182                                         /* Initialise the file locks: */
 183                                         memset(&_thread_fd_table[i]->lock, 0,
 184                                             sizeof(_thread_fd_table[i]->lock));
 185                                         _thread_fd_table[i]->r_owner = NULL;
 186                                         _thread_fd_table[i]->w_owner = NULL;
 187                                         _thread_fd_table[i]->r_fname = NULL;
 188                                         _thread_fd_table[i]->w_fname = NULL;
 189                                         _thread_fd_table[i]->r_lineno = 0;
 190                                         _thread_fd_table[i]->w_lineno = 0;
 191                                         _thread_fd_table[i]->r_lockcount = 0;
 192                                         _thread_fd_table[i]->w_lockcount = 0;
 193
 194                                         /* Initialise the read/write queues: */
 195                                         TAILQ_INIT(&_thread_fd_table[i]->r_queue);
 196                                         TAILQ_INIT(&_thread_fd_table[i]->w_queue);
 197                                 }
 198                         }
 199                 }
 200                 /* Run down atfork child handlers. */
 201                 TAILQ_FOREACH(af, &_atfork_list, qe) {
 202                         if (af->child != NULL)
 203                                 af->child();
 204                         }
 205                 _mutex_reinit(&_atfork_mutex);
 206         }
 207
 208         /*
 209          * Undefer and handle pending signals, yielding if necessary:
 210          */
 211         _thread_kern_sig_undefer();
 212
 213         /* Return the process ID: */
 214         return (ret);
 215 }
 216
 217 __strong_reference(_fork, fork);