fed06968ba
I've been meaning to do this for AGES as I keep having to patch those routines whenever I write a proprietary package or similar.. any module that assigns resources to processes needs to know when these events occur. there are existsing modules that should be modified to take advantage of these.. e.g. SYSV IPC primatives presently have #ifdef entries in exit() this also helps with making LKMs out of such things.. (see the man pages at_exit(9) and at_fork(9))
437 lines
11 KiB
C
437 lines
11 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 1.23 1996/07/31 09:26:34 davidg 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/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/file.h>
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#include <sys/acct.h>
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#include <sys/ktrace.h>
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#include <vm/vm.h>
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#include <vm/vm_param.h>
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#include <vm/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_inherit.h>
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static int fork1 __P((struct proc *p, int flags, int *retval));
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/*
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* callout list for things to do at fork time
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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, retval)
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struct proc *p;
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struct fork_args *uap;
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int retval[];
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{
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return (fork1(p, (RFFDG|RFPROC), retval));
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}
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/* ARGSUSED */
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int
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vfork(p, uap, retval)
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struct proc *p;
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struct vfork_args *uap;
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int retval[];
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{
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return (fork1(p, (RFFDG|RFPROC|RFPPWAIT), retval));
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}
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/* ARGSUSED */
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int
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rfork(p, uap, retval)
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struct proc *p;
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struct rfork_args *uap;
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int retval[];
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{
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return (fork1(p, uap->flags, retval));
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}
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int nprocs = 1; /* process 0 */
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static int
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fork1(p1, flags, retval)
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register struct proc *p1;
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int flags;
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int retval[];
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{
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register struct proc *p2, *pptr;
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register uid_t uid;
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struct proc *newproc;
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int count;
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static int nextpid, pidchecked = 0;
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fle_p ep = fork_list;
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if ((flags & RFPROC) == 0)
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return (EINVAL);
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if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
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return (EINVAL);
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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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MALLOC(newproc, struct proc *, sizeof(struct proc), M_PROC, M_WAITOK);
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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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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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}
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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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/*
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* XXX: this should be done as part of the startzero above
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*/
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p2->p_vmspace = 0; /* XXX */
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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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/* 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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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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p1->p_flag |= P_NOSWAP;
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/*
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* share as much address space as possible
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* XXX this should probably go in vm_fork()
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*/
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if (flags & RFMEM)
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(void) vm_map_inherit(&p1->p_vmspace->vm_map,
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VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS - MAXSSIZ,
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VM_INHERIT_SHARE);
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/*
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* Set return values for child before vm_fork,
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* so they can be copied to child stack.
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* We return parent pid, and mark as child in retval[1].
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* NOTE: the kernel stack may be at a different location in the child
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* process, and thus addresses of automatic variables (including retval)
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* may be invalid after vm_fork returns in the child process.
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*/
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retval[0] = p1->p_pid;
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retval[1] = 1;
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if (vm_fork(p1, p2)) {
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/*
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* Child process. Set start time and get to work.
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*/
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microtime(&runtime);
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p2->p_stats->p_start = runtime;
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p2->p_acflag = AFORK;
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return (0);
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}
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/*
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* Both processes are set up,
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* check if any LKMs want 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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(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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p1->p_flag &= ~P_NOSWAP;
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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 pid to parent process,
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* marking us as parent via retval[1].
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*/
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retval[0] = p2->p_pid;
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retval[1] = 0;
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return (0);
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}
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/*********************************************************
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* general routines to handle adding/deleting items on the
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* fork callout list
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*****
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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.
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*/
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int
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at_fork(forklist_fn function)
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{
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fle_p ep;
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if(rm_at_fork(function)) {
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printf("fork callout entry already present\n");
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}
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ep = malloc(sizeof(*ep),M_TEMP,M_NOWAIT);
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if(!ep) return ENOMEM;
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ep->next = fork_list;
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ep->function = function;
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fork_list = ep;
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return 0;
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}
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/*
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* Scan the exit callout list for the given items and remove them.
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* Returns the number of items removed.
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*/
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int
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rm_at_fork(forklist_fn function)
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{
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fle_p *epp,ep;
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int count = 0;
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epp = &fork_list;
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ep = *epp;
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while(ep) {
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if(ep->function == function) {
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*epp = ep->next;
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free(ep,M_TEMP);
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count++;
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} else {
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epp = &ep->next;
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}
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ep = *epp;
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}
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return count;
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}
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