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  * $DragonFly: src/lib/libc_r/uthread/uthread_fork.c,v 1.2 2003/06/17 04:26:48 dillon Exp $
  34  */
  35 #include <errno.h>
  36 #include <string.h>
  37 #include <stdlib.h>
  38 #include <unistd.h>
  39 #include <fcntl.h>
  40 #include <pthread.h>
  41 #include "pthread_private.h"
  42
  43 pid_t
  44 _fork(void)
  45 {
  46         struct pthread  *curthread = _get_curthread();
  47         int             i, flags;
  48         pid_t           ret;
  49         pthread_t       pthread;
  50         pthread_t       pthread_save;
  51
  52         /*
  53          * Defer signals to protect the scheduling queues from access
  54          * by the signal handler:
  55          */
  56         _thread_kern_sig_defer();
  57
  58         /* Fork a new process: */
  59         if ((ret = __sys_fork()) != 0) {
  60                 /* Parent process or error. Nothing to do here. */
  61         } else {
  62                 /* Close the pthread kernel pipe: */
  63                 __sys_close(_thread_kern_pipe[0]);
  64                 __sys_close(_thread_kern_pipe[1]);
  65
  66                 /* Reset signals pending for the running thread: */
  67                 sigemptyset(&curthread->sigpend);
  68
  69                 /*
  70                  * Create a pipe that is written to by the signal handler to
  71                  * prevent signals being missed in calls to
  72                  * __sys_select:
  73                  */
  74                 if (__sys_pipe(_thread_kern_pipe) != 0) {
  75                         /* Cannot create pipe, so abort: */
  76                         PANIC("Cannot create pthread kernel pipe for forked process");
  77                 }
  78                 /* Get the flags for the read pipe: */
  79                 else if ((flags = __sys_fcntl(_thread_kern_pipe[0], F_GETFL, NULL)) == -1) {
  80                         /* Abort this application: */
  81                         abort();
  82                 }
  83                 /* Make the read pipe non-blocking: */
  84                 else if (__sys_fcntl(_thread_kern_pipe[0], F_SETFL, flags | O_NONBLOCK) == -1) {
  85                         /* Abort this application: */
  86                         abort();
  87                 }
  88                 /* Get the flags for the write pipe: */
  89                 else if ((flags = __sys_fcntl(_thread_kern_pipe[1], F_GETFL, NULL)) == -1) {
  90                         /* Abort this application: */
  91                         abort();
  92                 }
  93                 /* Make the write pipe non-blocking: */
  94                 else if (__sys_fcntl(_thread_kern_pipe[1], F_SETFL, flags | O_NONBLOCK) == -1) {
  95                         /* Abort this application: */
  96                         abort();
  97                 }
  98                 /* Reinitialize the GC mutex: */
  99                 else if (_mutex_reinit(&_gc_mutex) != 0) {
 100                         /* Abort this application: */
 101                         PANIC("Cannot initialize GC mutex for forked process");
 102                 }
 103                 /* Reinitialize the GC condition variable: */
 104                 else if (_cond_reinit(&_gc_cond) != 0) {
 105                         /* Abort this application: */
 106                         PANIC("Cannot initialize GC condvar for forked process");
 107                 }
 108                 /* Initialize the ready queue: */
 109                 else if (_pq_init(&_readyq) != 0) {
 110                         /* Abort this application: */
 111                         PANIC("Cannot initialize priority ready queue.");
 112                 } else {
 113                         /*
 114                          * Enter a loop to remove all threads other than
 115                          * the running thread from the thread list:
 116                          */
 117                         pthread = TAILQ_FIRST(&_thread_list);
 118                         while (pthread != NULL) {
 119                                 /* Save the thread to be freed: */
 120                                 pthread_save = pthread;
 121
 122                                 /*
 123                                  * Advance to the next thread before
 124                                  * destroying the current thread:
 125                                  */
 126                                 pthread = TAILQ_NEXT(pthread, tle);
 127
 128                                 /* Make sure this isn't the running thread: */
 129                                 if (pthread_save != curthread) {
 130                                         /* Remove this thread from the list: */
 131                                         TAILQ_REMOVE(&_thread_list,
 132                                             pthread_save, tle);
 133
 134                                         if (pthread_save->attr.stackaddr_attr ==
 135                                             NULL && pthread_save->stack != NULL) {
 136                                                 if (pthread_save->attr.stacksize_attr
 137                                                     == PTHREAD_STACK_DEFAULT) {
 138                                                         /*
 139                                                          * Default-size stack.
 140                                                          * Cache it:
 141                                                          */
 142                                                         struct stack    *spare_stack;
 143
 144                                                         spare_stack
 145                                                             = (pthread_save->stack
 146                                                             + PTHREAD_STACK_DEFAULT
 147                                                             - sizeof(struct stack));
 148                                                         SLIST_INSERT_HEAD(&_stackq,
 149                                                             spare_stack, qe);
 150                                                 } else
 151                                                         /*
 152                                                          * Free the stack of
 153                                                          * the dead thread:
 154                                                          */
 155                                                         free(pthread_save->stack);
 156                                         }
 157
 158                                         if (pthread_save->specific_data != NULL)
 159                                                 free(pthread_save->specific_data);
 160
 161                                         if (pthread_save->poll_data.fds != NULL)
 162                                                 free(pthread_save->poll_data.fds);
 163
 164                                         free(pthread_save);
 165                                 }
 166                         }
 167
 168                         /* Treat the current thread as the initial thread: */
 169                         _thread_initial = curthread;
 170
 171                         /* Re-init the dead thread list: */
 172                         TAILQ_INIT(&_dead_list);
 173
 174                         /* Re-init the waiting and work queues. */
 175                         TAILQ_INIT(&_waitingq);
 176                         TAILQ_INIT(&_workq);
 177
 178                         /* Re-init the threads mutex queue: */
 179                         TAILQ_INIT(&curthread->mutexq);
 180
 181                         /* No spinlocks yet: */
 182                         _spinblock_count = 0;
 183
 184                         /* Don't queue signals yet: */
 185                         _queue_signals = 0;
 186
 187                         /* Initialize the scheduling switch hook routine: */
 188                         _sched_switch_hook = NULL;
 189
 190                         /* Clear out any locks in the file descriptor table: */
 191                         for (i = 0; i < _thread_dtablesize; i++) {
 192                                 if (_thread_fd_table[i] != NULL) {
 193                                         /* Initialise the file locks: */
 194                                         memset(&_thread_fd_table[i]->lock, 0,
 195                                             sizeof(_thread_fd_table[i]->lock));
 196                                         _thread_fd_table[i]->r_owner = NULL;
 197                                         _thread_fd_table[i]->w_owner = NULL;
 198                                         _thread_fd_table[i]->r_fname = NULL;
 199                                         _thread_fd_table[i]->w_fname = NULL;
 200                                         _thread_fd_table[i]->r_lineno = 0;;
 201                                         _thread_fd_table[i]->w_lineno = 0;;
 202                                         _thread_fd_table[i]->r_lockcount = 0;;
 203                                         _thread_fd_table[i]->w_lockcount = 0;;
 204
 205                                         /* Initialise the read/write queues: */
 206                                         TAILQ_INIT(&_thread_fd_table[i]->r_queue);
 207                                         TAILQ_INIT(&_thread_fd_table[i]->w_queue);
 208                                 }
 209                         }
 210                 }
 211         }
 212
 213         /*
 214          * Undefer and handle pending signals, yielding if necessary:
 215          */
 216         _thread_kern_sig_undefer();
 217
 218         /* Return the process ID: */
 219         return (ret);
 220 }
 221
 222 __strong_reference(_fork, fork);