df8abd0bb9
the caller can easily find the child proc struct. fork(), rfork() etc syscalls set p->p_retval[] themselves. Simplify the SYSINIT_KT() code and other kernel thread creators to not need to use pfind() to find the child based on the pid. While here, partly tidy up some of the fork1() code for RF_SIGSHARE etc.
548 lines
13 KiB
C
548 lines
13 KiB
C
/*
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* Copyright (c) 1982, 1986, 1989, 1991, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)kern_fork.c 8.6 (Berkeley) 4/8/94
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* $Id: kern_fork.c,v 1.61 1999/04/28 11:36:53 phk Exp $
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*/
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#include "opt_ktrace.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/sysproto.h>
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#include <sys/filedesc.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <sys/malloc.h>
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#include <sys/proc.h>
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#include <sys/resourcevar.h>
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#include <sys/vnode.h>
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#include <sys/acct.h>
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#include <sys/ktrace.h>
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#include <sys/unistd.h>
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#include <sys/jail.h>
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#include <vm/vm.h>
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#include <sys/lock.h>
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#include <vm/pmap.h>
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#include <vm/vm_map.h>
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#include <vm/vm_extern.h>
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#include <vm/vm_zone.h>
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#include <machine/frame.h>
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#include <sys/user.h>
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static int fast_vfork = 1;
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SYSCTL_INT(_kern, OID_AUTO, fast_vfork, CTLFLAG_RW, &fast_vfork, 0, "");
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/*
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* These are the stuctures used to create a callout list for things to do
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* when forking a process
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*/
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typedef struct fork_list_element {
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struct fork_list_element *next;
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forklist_fn function;
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} *fle_p;
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static fle_p fork_list;
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#ifndef _SYS_SYSPROTO_H_
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struct fork_args {
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int dummy;
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};
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#endif
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/* ARGSUSED */
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int
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fork(p, uap)
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struct proc *p;
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struct fork_args *uap;
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{
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int error;
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struct proc *p2;
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error = fork1(p, RFFDG | RFPROC, &p2);
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if (error == 0) {
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p->p_retval[0] = p2->p_pid;
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p->p_retval[1] = 0;
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}
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return error;
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}
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/* ARGSUSED */
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int
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vfork(p, uap)
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struct proc *p;
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struct vfork_args *uap;
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{
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int error;
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struct proc *p2;
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error = fork1(p, RFFDG | RFPROC | RFPPWAIT | RFMEM, &p2);
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if (error == 0) {
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p->p_retval[0] = p2->p_pid;
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p->p_retval[1] = 0;
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}
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return error;
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}
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int
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rfork(p, uap)
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struct proc *p;
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struct rfork_args *uap;
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{
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int error;
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struct proc *p2;
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error = fork1(p, uap->flags, &p2);
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if (error == 0) {
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p->p_retval[0] = p2->p_pid;
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p->p_retval[1] = 0;
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}
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return error;
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}
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int nprocs = 1; /* process 0 */
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static int nextpid = 0;
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int
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fork1(p1, flags, procp)
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struct proc *p1;
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int flags;
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struct proc **procp;
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{
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struct proc *p2, *pptr;
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uid_t uid;
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struct proc *newproc;
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int count;
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static int pidchecked = 0;
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fle_p ep ;
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ep = fork_list;
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if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
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return (EINVAL);
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/*
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* Here we don't create a new process, but we divorce
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* certain parts of a process from itself.
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*/
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if ((flags & RFPROC) == 0) {
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/*
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* Divorce the memory, if it is shared, essentially
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* this changes shared memory amongst threads, into
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* COW locally.
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*/
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if ((flags & RFMEM) == 0) {
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if (p1->p_vmspace->vm_refcnt > 1) {
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vmspace_unshare(p1);
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}
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}
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/*
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* Close all file descriptors.
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*/
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if (flags & RFCFDG) {
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struct filedesc *fdtmp;
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fdtmp = fdinit(p1);
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fdfree(p1);
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p1->p_fd = fdtmp;
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}
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/*
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* Unshare file descriptors (from parent.)
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*/
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if (flags & RFFDG) {
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if (p1->p_fd->fd_refcnt > 1) {
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struct filedesc *newfd;
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newfd = fdcopy(p1);
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fdfree(p1);
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p1->p_fd = newfd;
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}
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}
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return (0);
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}
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/*
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* Although process entries are dynamically created, we still keep
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* a global limit on the maximum number we will create. Don't allow
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* a nonprivileged user to use the last process; don't let root
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* exceed the limit. The variable nprocs is the current number of
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* processes, maxproc is the limit.
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*/
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uid = p1->p_cred->p_ruid;
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if ((nprocs >= maxproc - 1 && uid != 0) || nprocs >= maxproc) {
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tablefull("proc");
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return (EAGAIN);
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}
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/*
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* Increment the nprocs resource before blocking can occur. There
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* are hard-limits as to the number of processes that can run.
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*/
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nprocs++;
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/*
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* Increment the count of procs running with this uid. Don't allow
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* a nonprivileged user to exceed their current limit.
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*/
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count = chgproccnt(uid, 1);
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if (uid != 0 && count > p1->p_rlimit[RLIMIT_NPROC].rlim_cur) {
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(void)chgproccnt(uid, -1);
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/*
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* Back out the process count
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*/
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nprocs--;
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return (EAGAIN);
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}
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/* Allocate new proc. */
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newproc = zalloc(proc_zone);
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/*
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* Setup linkage for kernel based threading
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*/
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if((flags & RFTHREAD) != 0) {
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newproc->p_peers = p1->p_peers;
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p1->p_peers = newproc;
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newproc->p_leader = p1->p_leader;
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} else {
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newproc->p_peers = 0;
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newproc->p_leader = newproc;
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}
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newproc->p_wakeup = 0;
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/*
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* Find an unused process ID. We remember a range of unused IDs
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* ready to use (from nextpid+1 through pidchecked-1).
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*/
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nextpid++;
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retry:
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/*
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* If the process ID prototype has wrapped around,
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* restart somewhat above 0, as the low-numbered procs
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* tend to include daemons that don't exit.
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*/
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if (nextpid >= PID_MAX) {
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nextpid = 100;
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pidchecked = 0;
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}
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if (nextpid >= pidchecked) {
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int doingzomb = 0;
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pidchecked = PID_MAX;
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/*
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* Scan the active and zombie procs to check whether this pid
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* is in use. Remember the lowest pid that's greater
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* than nextpid, so we can avoid checking for a while.
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*/
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p2 = allproc.lh_first;
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again:
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for (; p2 != 0; p2 = p2->p_list.le_next) {
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while (p2->p_pid == nextpid ||
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p2->p_pgrp->pg_id == nextpid ||
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p2->p_session->s_sid == nextpid) {
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nextpid++;
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if (nextpid >= pidchecked)
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goto retry;
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}
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if (p2->p_pid > nextpid && pidchecked > p2->p_pid)
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pidchecked = p2->p_pid;
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if (p2->p_pgrp->pg_id > nextpid &&
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pidchecked > p2->p_pgrp->pg_id)
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pidchecked = p2->p_pgrp->pg_id;
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if (p2->p_session->s_sid > nextpid &&
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pidchecked > p2->p_session->s_sid)
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pidchecked = p2->p_session->s_sid;
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}
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if (!doingzomb) {
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doingzomb = 1;
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p2 = zombproc.lh_first;
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goto again;
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}
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}
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p2 = newproc;
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p2->p_stat = SIDL; /* protect against others */
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p2->p_pid = nextpid;
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LIST_INSERT_HEAD(&allproc, p2, p_list);
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LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash);
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/*
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* Make a proc table entry for the new process.
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* Start by zeroing the section of proc that is zero-initialized,
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* then copy the section that is copied directly from the parent.
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*/
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bzero(&p2->p_startzero,
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(unsigned) ((caddr_t)&p2->p_endzero - (caddr_t)&p2->p_startzero));
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bcopy(&p1->p_startcopy, &p2->p_startcopy,
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(unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy));
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p2->p_aioinfo = NULL;
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/*
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* Duplicate sub-structures as needed.
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* Increase reference counts on shared objects.
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* The p_stats and p_sigacts substructs are set in vm_fork.
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*/
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p2->p_flag = P_INMEM;
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if (p1->p_flag & P_PROFIL)
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startprofclock(p2);
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MALLOC(p2->p_cred, struct pcred *, sizeof(struct pcred),
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M_SUBPROC, M_WAITOK);
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bcopy(p1->p_cred, p2->p_cred, sizeof(*p2->p_cred));
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p2->p_cred->p_refcnt = 1;
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crhold(p1->p_ucred);
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if (p2->p_prison) {
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p2->p_prison->pr_ref++;
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p2->p_flag |= P_JAILED;
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}
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if (flags & RFSIGSHARE) {
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p2->p_procsig = p1->p_procsig;
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p2->p_procsig->ps_refcnt++;
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if (p1->p_sigacts == &p1->p_addr->u_sigacts) {
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struct sigacts *newsigacts;
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int s;
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/* Create the shared sigacts structure */
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MALLOC(newsigacts, struct sigacts *,
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sizeof(struct sigacts), M_SUBPROC, M_WAITOK);
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s = splhigh();
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/*
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* Set p_sigacts to the new shared structure.
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* Note that this is updating p1->p_sigacts at the
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* same time, since p_sigacts is just a pointer to
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* the shared p_procsig->ps_sigacts.
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*/
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p2->p_sigacts = newsigacts;
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bcopy(&p1->p_addr->u_sigacts, p2->p_sigacts,
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sizeof(*p2->p_sigacts));
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*p2->p_sigacts = p1->p_addr->u_sigacts;
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splx(s);
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}
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} else {
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MALLOC(p2->p_procsig, struct procsig *, sizeof(struct procsig),
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M_SUBPROC, M_WAITOK);
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bcopy(p1->p_procsig, p2->p_procsig, sizeof(*p2->p_procsig));
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p2->p_procsig->ps_refcnt = 1;
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p2->p_sigacts = NULL; /* finished in vm_fork() */
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}
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if (flags & RFLINUXTHPN)
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p2->p_sigparent = SIGUSR1;
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else
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p2->p_sigparent = SIGCHLD;
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/* bump references to the text vnode (for procfs) */
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p2->p_textvp = p1->p_textvp;
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if (p2->p_textvp)
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VREF(p2->p_textvp);
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if (flags & RFCFDG)
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p2->p_fd = fdinit(p1);
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else if (flags & RFFDG)
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p2->p_fd = fdcopy(p1);
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else
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p2->p_fd = fdshare(p1);
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/*
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* If p_limit is still copy-on-write, bump refcnt,
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* otherwise get a copy that won't be modified.
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* (If PL_SHAREMOD is clear, the structure is shared
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* copy-on-write.)
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*/
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if (p1->p_limit->p_lflags & PL_SHAREMOD)
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p2->p_limit = limcopy(p1->p_limit);
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else {
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p2->p_limit = p1->p_limit;
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p2->p_limit->p_refcnt++;
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}
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/*
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* Preserve some more flags in subprocess. P_PROFIL has already
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* been preserved.
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*/
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p2->p_flag |= p1->p_flag & P_SUGID;
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if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)
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p2->p_flag |= P_CONTROLT;
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if (flags & RFPPWAIT)
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p2->p_flag |= P_PPWAIT;
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LIST_INSERT_AFTER(p1, p2, p_pglist);
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/*
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* Attach the new process to its parent.
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*
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* If RFNOWAIT is set, the newly created process becomes a child
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* of init. This effectively disassociates the child from the
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* parent.
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*/
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if (flags & RFNOWAIT)
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pptr = initproc;
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else
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pptr = p1;
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p2->p_pptr = pptr;
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LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling);
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LIST_INIT(&p2->p_children);
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#ifdef KTRACE
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/*
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* Copy traceflag and tracefile if enabled.
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* If not inherited, these were zeroed above.
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*/
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if (p1->p_traceflag&KTRFAC_INHERIT) {
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p2->p_traceflag = p1->p_traceflag;
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if ((p2->p_tracep = p1->p_tracep) != NULL)
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VREF(p2->p_tracep);
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}
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#endif
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/*
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* set priority of child to be that of parent
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*/
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p2->p_estcpu = p1->p_estcpu;
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/*
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* This begins the section where we must prevent the parent
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* from being swapped.
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*/
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PHOLD(p1);
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/*
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* Finish creating the child process. It will return via a different
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* execution path later. (ie: directly into user mode)
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*/
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vm_fork(p1, p2, flags);
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/*
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* Both processes are set up, now check if any loadable modules want
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* to adjust anything.
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* What if they have an error? XXX
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*/
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while (ep) {
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(*ep->function)(p1, p2, flags);
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ep = ep->next;
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}
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/*
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* Make child runnable and add to run queue.
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*/
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microtime(&(p2->p_stats->p_start));
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p2->p_acflag = AFORK;
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(void) splhigh();
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p2->p_stat = SRUN;
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setrunqueue(p2);
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(void) spl0();
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/*
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* Now can be swapped.
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*/
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PRELE(p1);
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/*
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* Preserve synchronization semantics of vfork. If waiting for
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* child to exec or exit, set P_PPWAIT on child, and sleep on our
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* proc (in case of exit).
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*/
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while (p2->p_flag & P_PPWAIT)
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tsleep(p1, PWAIT, "ppwait", 0);
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/*
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* Return child proc pointer to parent.
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*/
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*procp = p2;
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return (0);
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}
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/*
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* The next two functionms are general routines to handle adding/deleting
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* items on the fork callout list.
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*
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* at_fork():
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|
* Take the arguments given and put them onto the fork callout list,
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* However first make sure that it's not already there.
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* Returns 0 on success or a standard error number.
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*/
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|
int
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at_fork(function)
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|
forklist_fn function;
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|
{
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|
fle_p ep;
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|
|
/* let the programmer know if he's been stupid */
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|
if (rm_at_fork(function))
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printf("fork callout entry already present\n");
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|
ep = malloc(sizeof(*ep), M_TEMP, M_NOWAIT);
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|
if (ep == NULL)
|
|
return (ENOMEM);
|
|
ep->next = fork_list;
|
|
ep->function = function;
|
|
fork_list = ep;
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Scan the exit callout list for the given items and remove them.
|
|
* Returns the number of items removed.
|
|
* Theoretically this value can only be 0 or 1.
|
|
*/
|
|
int
|
|
rm_at_fork(function)
|
|
forklist_fn function;
|
|
{
|
|
fle_p *epp, ep;
|
|
int count;
|
|
|
|
count= 0;
|
|
epp = &fork_list;
|
|
ep = *epp;
|
|
while (ep) {
|
|
if (ep->function == function) {
|
|
*epp = ep->next;
|
|
free(ep, M_TEMP);
|
|
count++;
|
|
} else {
|
|
epp = &ep->next;
|
|
}
|
|
ep = *epp;
|
|
}
|
|
return (count);
|
|
}
|