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 1.5 2006/08/03 18:40:46 swildner 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                 _thread_mksigpipe();
  70
  71                 /* Reinitialize the GC mutex: */
  72                 if (_mutex_reinit(&_gc_mutex) != 0) {
  73                         /* Abort this application: */
  74                         PANIC("Cannot initialize GC mutex for forked process");
  75                 }
  76                 /* Reinitialize the GC condition variable: */
  77                 else if (_cond_reinit(&_gc_cond) != 0) {
  78                         /* Abort this application: */
  79                         PANIC("Cannot initialize GC condvar for forked process");
  80                 }
  81                 /* Initialize the ready queue: */
  82                 else if (_pq_init(&_readyq) != 0) {
  83                         /* Abort this application: */
  84                         PANIC("Cannot initialize priority ready queue.");
  85                 } else {
  86                         /*
  87                          * Enter a loop to remove all threads other than
  88                          * the running thread from the thread list:
  89                          */
  90                         pthread = TAILQ_FIRST(&_thread_list);
  91                         while (pthread != NULL) {
  92                                 /* Save the thread to be freed: */
  93                                 pthread_save = pthread;
  94
  95                                 /*
  96                                  * Advance to the next thread before
  97                                  * destroying the current thread:
  98                                  */
  99                                 pthread = TAILQ_NEXT(pthread, tle);
 100
 101                                 /* Make sure this isn't the running thread: */
 102                                 if (pthread_save != curthread) {
 103                                         /* Remove this thread from the list: */
 104                                         TAILQ_REMOVE(&_thread_list,
 105                                             pthread_save, tle);
 106
 107                                         if (pthread_save->attr.stackaddr_attr ==
 108                                             NULL && pthread_save->stack != NULL) {
 109                                                 if (pthread_save->attr.stacksize_attr
 110                                                     == PTHREAD_STACK_DEFAULT) {
 111                                                         /*
 112                                                          * Default-size stack.
 113                                                          * Cache it:
 114                                                          */
 115                                                         struct stack    *spare_stack;
 116
 117                                                         spare_stack
 118                                                             = (pthread_save->stack
 119                                                             + PTHREAD_STACK_DEFAULT
 120                                                             - sizeof(struct stack));
 121                                                         SLIST_INSERT_HEAD(&_stackq,
 122                                                             spare_stack, qe);
 123                                                 } else
 124                                                         /*
 125                                                          * Free the stack of
 126                                                          * the dead thread:
 127                                                          */
 128                                                         free(pthread_save->stack);
 129                                         }
 130
 131                                         if (pthread_save->specific_data != NULL)
 132                                                 free(pthread_save->specific_data);
 133
 134                                         if (pthread_save->poll_data.fds != NULL)
 135                                                 free(pthread_save->poll_data.fds);
 136
 137                                         _rtld_free_tls(pthread_save->tcb);
 138                                         free(pthread_save);
 139                                 }
 140                         }
 141
 142                         /* Treat the current thread as the initial thread: */
 143                         _thread_initial = curthread;
 144
 145                         /* Re-init the dead thread list: */
 146                         TAILQ_INIT(&_dead_list);
 147
 148                         /* Re-init the waiting and work queues. */
 149                         TAILQ_INIT(&_waitingq);
 150                         TAILQ_INIT(&_workq);
 151
 152                         /* Re-init the threads mutex queue: */
 153                         TAILQ_INIT(&curthread->mutexq);
 154
 155                         /* No spinlocks yet: */
 156                         _spinblock_count = 0;
 157
 158                         /* Don't queue signals yet: */
 159                         _queue_signals = 0;
 160
 161                         /* Initialize the scheduling switch hook routine: */
 162                         _sched_switch_hook = NULL;
 163
 164                         /* Clear out any locks in the file descriptor table: */
 165                         for (i = 0; i < _thread_dtablesize; i++) {
 166                                 if (_thread_fd_table[i] != NULL) {
 167                                         /* Initialise the file locks: */
 168                                         memset(&_thread_fd_table[i]->lock, 0,
 169                                             sizeof(_thread_fd_table[i]->lock));
 170                                         _thread_fd_table[i]->r_owner = NULL;
 171                                         _thread_fd_table[i]->w_owner = NULL;
 172                                         _thread_fd_table[i]->r_fname = NULL;
 173                                         _thread_fd_table[i]->w_fname = NULL;
 174                                         _thread_fd_table[i]->r_lineno = 0;
 175                                         _thread_fd_table[i]->w_lineno = 0;
 176                                         _thread_fd_table[i]->r_lockcount = 0;
 177                                         _thread_fd_table[i]->w_lockcount = 0;
 178
 179                                         /* Initialise the read/write queues: */
 180                                         TAILQ_INIT(&_thread_fd_table[i]->r_queue);
 181                                         TAILQ_INIT(&_thread_fd_table[i]->w_queue);
 182                                 }
 183                         }
 184                 }
 185         }
 186
 187         /*
 188          * Undefer and handle pending signals, yielding if necessary:
 189          */
 190         _thread_kern_sig_undefer();
 191
 192         /* Return the process ID: */
 193         return (ret);
 194 }
 195
 196 __strong_reference(_fork, fork);