lib/libpthread/thread/thr_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  * $FreeBSD$
  33  */
  34 #include <errno.h>
  35 #include <string.h>
  36 #include <unistd.h>
  37 #include <fcntl.h>
  38 #ifdef _THREAD_SAFE
  39 #include <pthread.h>
  40 #include "pthread_private.h"
  41
  42 pid_t
  43 fork(void)
  44 {
  45         int             i, flags;
  46         pid_t           ret;
  47         pthread_t       pthread;
  48         pthread_t       pthread_save;
  49
  50         /*
  51          * Defer signals to protect the scheduling queues from access
  52          * by the signal handler:
  53          */
  54         _thread_kern_sig_defer();
  55
  56         /* Fork a new process: */
  57         if ((ret = _thread_sys_fork()) != 0) {
  58                 /* Parent process or error. Nothing to do here. */
  59         } else {
  60                 /* Close the pthread kernel pipe: */
  61                 _thread_sys_close(_thread_kern_pipe[0]);
  62                 _thread_sys_close(_thread_kern_pipe[1]);
  63
  64                 /* Reset signals pending for the running thread: */
  65                 sigemptyset(&_thread_run->sigpend);
  66
  67                 /*
  68                  * Create a pipe that is written to by the signal handler to
  69                  * prevent signals being missed in calls to
  70                  * _thread_sys_select:
  71                  */
  72                 if (_thread_sys_pipe(_thread_kern_pipe) != 0) {
  73                         /* Cannot create pipe, so abort: */
  74                         PANIC("Cannot create pthread kernel pipe for forked process");
  75                 }
  76                 /* Get the flags for the read pipe: */
  77                 else if ((flags = _thread_sys_fcntl(_thread_kern_pipe[0], F_GETFL, NULL)) == -1) {
  78                         /* Abort this application: */
  79                         abort();
  80                 }
  81                 /* Make the read pipe non-blocking: */
  82                 else if (_thread_sys_fcntl(_thread_kern_pipe[0], F_SETFL, flags | O_NONBLOCK) == -1) {
  83                         /* Abort this application: */
  84                         abort();
  85                 }
  86                 /* Get the flags for the write pipe: */
  87                 else if ((flags = _thread_sys_fcntl(_thread_kern_pipe[1], F_GETFL, NULL)) == -1) {
  88                         /* Abort this application: */
  89                         abort();
  90                 }
  91                 /* Make the write pipe non-blocking: */
  92                 else if (_thread_sys_fcntl(_thread_kern_pipe[1], F_SETFL, flags | O_NONBLOCK) == -1) {
  93                         /* Abort this application: */
  94                         abort();
  95                 }
  96                 /* Reinitialize the GC mutex: */
  97                 else if (_mutex_reinit(&_gc_mutex) != 0) {
  98                         /* Abort this application: */
  99                         PANIC("Cannot initialize GC mutex for forked process");
 100                 }
 101                 /* Reinitialize the GC condition variable: */
 102                 else if (_cond_reinit(&_gc_cond) != 0) {
 103                         /* Abort this application: */
 104                         PANIC("Cannot initialize GC condvar for forked process");
 105                 }
 106                 /* Initialize the ready queue: */
 107                 else if (_pq_init(&_readyq) != 0) {
 108                         /* Abort this application: */
 109                         PANIC("Cannot initialize priority ready queue.");
 110                 } else {
 111                         /*
 112                          * Enter a loop to remove all threads other than
 113                          * the running thread from the thread list:
 114                          */
 115                         pthread = TAILQ_FIRST(&_thread_list);
 116                         while (pthread != NULL) {
 117                                 /* Save the thread to be freed: */
 118                                 pthread_save = pthread;
 119
 120                                 /*
 121                                  * Advance to the next thread before
 122                                  * destroying the current thread:
 123                                  */
 124                                 pthread = TAILQ_NEXT(pthread, dle);
 125
 126                                 /* Make sure this isn't the running thread: */
 127                                 if (pthread_save != _thread_run) {
 128                                         /* Remove this thread from the list: */
 129                                         TAILQ_REMOVE(&_thread_list,
 130                                             pthread_save, tle);
 131
 132                                         if (pthread_save->attr.stackaddr_attr ==
 133                                             NULL && pthread_save->stack != NULL)
 134                                                 if (pthread_save->attr.stacksize_attr
 135                                                     == PTHREAD_STACK_DEFAULT) {
 136                                                         /*
 137                                                          * Default-size stack.  Cache
 138                                                          * it:
 139                                                          */
 140                                                         struct stack    *spare_stack;
 141
 142                                                         spare_stack
 143                                                             = (pthread_save->stack
 144                                                                + PTHREAD_STACK_DEFAULT
 145                                                                - sizeof(struct stack));
 146                                                         SLIST_INSERT_HEAD(
 147                                                             &_stackq,
 148                                                             spare_stack,
 149                                                             qe);
 150                                                 } else
 151                                                         /*
 152                                                          * Free the stack of
 153                                                          * the dead thread:
 154                                                          */
 155                                                         free(pthread_save->stack);
 156
 157                                         if (pthread_save->specific_data != NULL)
 158                                                 free(pthread_save->specific_data);
 159
 160                                         if (pthread_save->poll_data.fds != NULL)
 161                                                 free(pthread_save->poll_data.fds);
 162
 163                                         free(pthread_save);
 164                                 }
 165                         }
 166
 167                         /* Treat the current thread as the initial thread: */
 168                         _thread_initial = _thread_run;
 169
 170                         /* Re-init the dead thread list: */
 171                         TAILQ_INIT(&_dead_list);
 172
 173                         /* Re-init the waiting and work queues. */
 174                         TAILQ_INIT(&_waitingq);
 175                         TAILQ_INIT(&_workq);
 176
 177                         /* Re-init the threads mutex queue: */
 178                         TAILQ_INIT(&_thread_run->mutexq);
 179
 180                         /* No spinlocks yet: */
 181                         _spinblock_count = 0;
 182
 183                         /* Don't queue signals yet: */
 184                         _queue_signals = 0;
 185
 186                         /* Initialize signal handling: */
 187                         _thread_sig_init();
 188
 189                         /* Initialize the scheduling switch hook routine: */
 190                         _sched_switch_hook = NULL;
 191
 192                         /* Clear out any locks in the file descriptor table: */
 193                         for (i = 0; i < _thread_dtablesize; i++) {
 194                                 if (_thread_fd_table[i] != NULL) {
 195                                         /* Initialise the file locks: */
 196                                         memset(&_thread_fd_table[i]->lock, 0,
 197                                             sizeof(_thread_fd_table[i]->lock));
 198                                         _thread_fd_table[i]->r_owner = NULL;
 199                                         _thread_fd_table[i]->w_owner = NULL;
 200                                         _thread_fd_table[i]->r_fname = NULL;
 201                                         _thread_fd_table[i]->w_fname = NULL;
 202                                         _thread_fd_table[i]->r_lineno = 0;;
 203                                         _thread_fd_table[i]->w_lineno = 0;;
 204                                         _thread_fd_table[i]->r_lockcount = 0;;
 205                                         _thread_fd_table[i]->w_lockcount = 0;;
 206
 207                                         /* Initialise the read/write queues: */
 208                                         TAILQ_INIT(&_thread_fd_table[i]->r_queue);
 209                                         TAILQ_INIT(&_thread_fd_table[i]->w_queue);
 210                                 }
 211                         }
 212                 }
 213         }
 214
 215         /*
 216          * Undefer and handle pending signals, yielding if necessary:
 217          */
 218         _thread_kern_sig_undefer();
 219
 220         /* Return the process ID: */
 221         return (ret);
 222 }
 223 #endif