504 lines
12 KiB
C
504 lines
12 KiB
C
/*
|
|
* Copyright (c) 1982, 1986, 1989, 1991, 1993
|
|
* The Regents of the University of California. All rights reserved.
|
|
* (c) UNIX System Laboratories, Inc.
|
|
* All or some portions of this file are derived from material licensed
|
|
* to the University of California by American Telephone and Telegraph
|
|
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
|
|
* the permission of UNIX System Laboratories, Inc.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
|
* 4. Neither the name of the University nor the names of its contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* @(#)kern_fork.c 8.6 (Berkeley) 4/8/94
|
|
* $Id: kern_fork.c,v 1.45 1997/07/06 02:40:41 dyson Exp $
|
|
*/
|
|
|
|
#include "opt_ktrace.h"
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/sysproto.h>
|
|
#include <sys/filedesc.h>
|
|
#include <sys/kernel.h>
|
|
#include <sys/sysctl.h>
|
|
#include <sys/malloc.h>
|
|
#include <sys/proc.h>
|
|
#include <sys/resourcevar.h>
|
|
#include <sys/vnode.h>
|
|
#include <sys/acct.h>
|
|
#include <sys/ktrace.h>
|
|
#include <sys/unistd.h>
|
|
|
|
#include <vm/vm.h>
|
|
#include <vm/vm_param.h>
|
|
#include <sys/lock.h>
|
|
#include <vm/pmap.h>
|
|
#include <vm/vm_map.h>
|
|
#include <vm/vm_extern.h>
|
|
#include <vm/vm_inherit.h>
|
|
|
|
#ifdef SMP
|
|
int fast_vfork = 0; /* Doesn't work on SMP yet */
|
|
#else
|
|
int fast_vfork = 1;
|
|
#endif
|
|
SYSCTL_INT(_kern, OID_AUTO, fast_vfork, CTLFLAG_RW, &fast_vfork, 0, "");
|
|
|
|
static int fork1 __P((struct proc *p, int flags, int *retval));
|
|
|
|
/*
|
|
* These are the stuctures used to create a callout list for things to do
|
|
* when forking a process
|
|
*/
|
|
typedef struct fork_list_element {
|
|
struct fork_list_element *next;
|
|
forklist_fn function;
|
|
} *fle_p;
|
|
|
|
static fle_p fork_list;
|
|
|
|
#ifndef _SYS_SYSPROTO_H_
|
|
struct fork_args {
|
|
int dummy;
|
|
};
|
|
#endif
|
|
|
|
/* ARGSUSED */
|
|
int
|
|
fork(p, uap, retval)
|
|
struct proc *p;
|
|
struct fork_args *uap;
|
|
int retval[];
|
|
{
|
|
return (fork1(p, (RFFDG|RFPROC), retval));
|
|
}
|
|
|
|
/* ARGSUSED */
|
|
int
|
|
vfork(p, uap, retval)
|
|
struct proc *p;
|
|
struct vfork_args *uap;
|
|
int retval[];
|
|
{
|
|
return (fork1(p, (RFFDG|RFPROC|RFPPWAIT|(fast_vfork ? RFMEM : 0)),
|
|
retval));
|
|
}
|
|
|
|
/* ARGSUSED */
|
|
int
|
|
rfork(p, uap, retval)
|
|
struct proc *p;
|
|
struct rfork_args *uap;
|
|
int retval[];
|
|
{
|
|
return (fork1(p, uap->flags, retval));
|
|
}
|
|
|
|
|
|
int nprocs = 1; /* process 0 */
|
|
static int nextpid = 0;
|
|
|
|
static int
|
|
fork1(p1, flags, retval)
|
|
register struct proc *p1;
|
|
int flags;
|
|
int retval[];
|
|
{
|
|
register struct proc *p2, *pptr;
|
|
register uid_t uid;
|
|
struct proc *newproc;
|
|
int count;
|
|
static int pidchecked = 0;
|
|
fle_p ep ;
|
|
|
|
ep = fork_list;
|
|
|
|
if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
|
|
return (EINVAL);
|
|
|
|
#ifdef SMP
|
|
/*
|
|
* FATAL now, we cannot have the same PTD on both cpus, the PTD
|
|
* needs to move out of PTmap and be per-process, even for shared
|
|
* page table processes. Unfortunately, this means either removing
|
|
* PTD[] as a fixed virtual address, or move it to the per-cpu map
|
|
* area for SMP mode. Both cases require seperate management of
|
|
* the per-process-even-if-PTmap-is-shared PTD.
|
|
*/
|
|
if (flags & RFMEM) {
|
|
printf("shared address space fork attempted: pid: %d\n",
|
|
p1->p_pid);
|
|
return (EOPNOTSUPP);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Here we don't create a new process, but we divorce
|
|
* certain parts of a process from itself.
|
|
*/
|
|
if ((flags & RFPROC) == 0) {
|
|
|
|
/*
|
|
* Divorce the memory, if it is shared, essentially
|
|
* this changes shared memory amongst threads, into
|
|
* COW locally.
|
|
*/
|
|
if ((flags & RFMEM) == 0) {
|
|
if (p1->p_vmspace->vm_refcnt > 1) {
|
|
vmspace_unshare(p1);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Close all file descriptors.
|
|
*/
|
|
if (flags & RFCFDG) {
|
|
struct filedesc *fdtmp;
|
|
fdtmp = fdinit(p1);
|
|
fdfree(p1);
|
|
p1->p_fd = fdtmp;
|
|
}
|
|
|
|
/*
|
|
* Unshare file descriptors (from parent.)
|
|
*/
|
|
if (flags & RFFDG) {
|
|
if (p1->p_fd->fd_refcnt > 1) {
|
|
struct filedesc *newfd;
|
|
newfd = fdcopy(p1);
|
|
fdfree(p1);
|
|
p1->p_fd = newfd;
|
|
}
|
|
}
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Although process entries are dynamically created, we still keep
|
|
* a global limit on the maximum number we will create. Don't allow
|
|
* a nonprivileged user to use the last process; don't let root
|
|
* exceed the limit. The variable nprocs is the current number of
|
|
* processes, maxproc is the limit.
|
|
*/
|
|
uid = p1->p_cred->p_ruid;
|
|
if ((nprocs >= maxproc - 1 && uid != 0) || nprocs >= maxproc) {
|
|
tablefull("proc");
|
|
return (EAGAIN);
|
|
}
|
|
/*
|
|
* Increment the nprocs resource before blocking can occur. There
|
|
* are hard-limits as to the number of processes that can run.
|
|
*/
|
|
nprocs++;
|
|
|
|
/*
|
|
* Increment the count of procs running with this uid. Don't allow
|
|
* a nonprivileged user to exceed their current limit.
|
|
*/
|
|
count = chgproccnt(uid, 1);
|
|
if (uid != 0 && count > p1->p_rlimit[RLIMIT_NPROC].rlim_cur) {
|
|
(void)chgproccnt(uid, -1);
|
|
/*
|
|
* Back out the process count
|
|
*/
|
|
nprocs--;
|
|
return (EAGAIN);
|
|
}
|
|
|
|
/* Allocate new proc. */
|
|
MALLOC(newproc, struct proc *, sizeof(struct proc), M_PROC, M_WAITOK);
|
|
|
|
/*
|
|
* Setup linkage for kernel based threading
|
|
*/
|
|
if((flags & RFTHREAD) != 0) {
|
|
newproc->p_peers = p1->p_peers;
|
|
p1->p_peers = newproc;
|
|
newproc->p_leader = p1->p_leader;
|
|
} else {
|
|
newproc->p_peers = 0;
|
|
newproc->p_leader = newproc;
|
|
}
|
|
|
|
newproc->p_wakeup = 0;
|
|
|
|
/*
|
|
* Find an unused process ID. We remember a range of unused IDs
|
|
* ready to use (from nextpid+1 through pidchecked-1).
|
|
*/
|
|
nextpid++;
|
|
retry:
|
|
/*
|
|
* If the process ID prototype has wrapped around,
|
|
* restart somewhat above 0, as the low-numbered procs
|
|
* tend to include daemons that don't exit.
|
|
*/
|
|
if (nextpid >= PID_MAX) {
|
|
nextpid = 100;
|
|
pidchecked = 0;
|
|
}
|
|
if (nextpid >= pidchecked) {
|
|
int doingzomb = 0;
|
|
|
|
pidchecked = PID_MAX;
|
|
/*
|
|
* Scan the active and zombie procs to check whether this pid
|
|
* is in use. Remember the lowest pid that's greater
|
|
* than nextpid, so we can avoid checking for a while.
|
|
*/
|
|
p2 = allproc.lh_first;
|
|
again:
|
|
for (; p2 != 0; p2 = p2->p_list.le_next) {
|
|
while (p2->p_pid == nextpid ||
|
|
p2->p_pgrp->pg_id == nextpid) {
|
|
nextpid++;
|
|
if (nextpid >= pidchecked)
|
|
goto retry;
|
|
}
|
|
if (p2->p_pid > nextpid && pidchecked > p2->p_pid)
|
|
pidchecked = p2->p_pid;
|
|
if (p2->p_pgrp->pg_id > nextpid &&
|
|
pidchecked > p2->p_pgrp->pg_id)
|
|
pidchecked = p2->p_pgrp->pg_id;
|
|
}
|
|
if (!doingzomb) {
|
|
doingzomb = 1;
|
|
p2 = zombproc.lh_first;
|
|
goto again;
|
|
}
|
|
}
|
|
|
|
p2 = newproc;
|
|
p2->p_stat = SIDL; /* protect against others */
|
|
p2->p_pid = nextpid;
|
|
LIST_INSERT_HEAD(&allproc, p2, p_list);
|
|
LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash);
|
|
|
|
/*
|
|
* Make a proc table entry for the new process.
|
|
* Start by zeroing the section of proc that is zero-initialized,
|
|
* then copy the section that is copied directly from the parent.
|
|
*/
|
|
bzero(&p2->p_startzero,
|
|
(unsigned) ((caddr_t)&p2->p_endzero - (caddr_t)&p2->p_startzero));
|
|
bcopy(&p1->p_startcopy, &p2->p_startcopy,
|
|
(unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy));
|
|
|
|
p2->p_aioinfo = NULL;
|
|
|
|
/*
|
|
* Duplicate sub-structures as needed.
|
|
* Increase reference counts on shared objects.
|
|
* The p_stats and p_sigacts substructs are set in vm_fork.
|
|
*/
|
|
p2->p_flag = P_INMEM;
|
|
if (p1->p_flag & P_PROFIL)
|
|
startprofclock(p2);
|
|
MALLOC(p2->p_cred, struct pcred *, sizeof(struct pcred),
|
|
M_SUBPROC, M_WAITOK);
|
|
bcopy(p1->p_cred, p2->p_cred, sizeof(*p2->p_cred));
|
|
p2->p_cred->p_refcnt = 1;
|
|
crhold(p1->p_ucred);
|
|
|
|
/* bump references to the text vnode (for procfs) */
|
|
p2->p_textvp = p1->p_textvp;
|
|
if (p2->p_textvp)
|
|
VREF(p2->p_textvp);
|
|
|
|
if (flags & RFCFDG)
|
|
p2->p_fd = fdinit(p1);
|
|
else if (flags & RFFDG)
|
|
p2->p_fd = fdcopy(p1);
|
|
else
|
|
p2->p_fd = fdshare(p1);
|
|
|
|
/*
|
|
* If p_limit is still copy-on-write, bump refcnt,
|
|
* otherwise get a copy that won't be modified.
|
|
* (If PL_SHAREMOD is clear, the structure is shared
|
|
* copy-on-write.)
|
|
*/
|
|
if (p1->p_limit->p_lflags & PL_SHAREMOD)
|
|
p2->p_limit = limcopy(p1->p_limit);
|
|
else {
|
|
p2->p_limit = p1->p_limit;
|
|
p2->p_limit->p_refcnt++;
|
|
}
|
|
|
|
/*
|
|
* Preserve some flags in subprocess.
|
|
*/
|
|
p2->p_flag |= p1->p_flag & P_SUGID;
|
|
if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)
|
|
p2->p_flag |= P_CONTROLT;
|
|
if (flags & RFPPWAIT)
|
|
p2->p_flag |= P_PPWAIT;
|
|
LIST_INSERT_AFTER(p1, p2, p_pglist);
|
|
|
|
/*
|
|
* Attach the new process to its parent.
|
|
*
|
|
* If RFNOWAIT is set, the newly created process becomes a child
|
|
* of init. This effectively disassociates the child from the
|
|
* parent.
|
|
*/
|
|
if (flags & RFNOWAIT)
|
|
pptr = initproc;
|
|
else
|
|
pptr = p1;
|
|
p2->p_pptr = pptr;
|
|
LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling);
|
|
LIST_INIT(&p2->p_children);
|
|
|
|
#ifdef KTRACE
|
|
/*
|
|
* Copy traceflag and tracefile if enabled.
|
|
* If not inherited, these were zeroed above.
|
|
*/
|
|
if (p1->p_traceflag&KTRFAC_INHERIT) {
|
|
p2->p_traceflag = p1->p_traceflag;
|
|
if ((p2->p_tracep = p1->p_tracep) != NULL)
|
|
VREF(p2->p_tracep);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* set priority of child to be that of parent
|
|
*/
|
|
p2->p_estcpu = p1->p_estcpu;
|
|
|
|
/*
|
|
* This begins the section where we must prevent the parent
|
|
* from being swapped.
|
|
*/
|
|
p1->p_flag |= P_NOSWAP;
|
|
|
|
/*
|
|
* Finish creating the child process. It will return via a different
|
|
* execution path later. (ie: directly into user mode)
|
|
*/
|
|
vm_fork(p1, p2, flags);
|
|
|
|
/*
|
|
* Both processes are set up, now check if any LKMs want
|
|
* to adjust anything.
|
|
* What if they have an error? XXX
|
|
*/
|
|
while (ep) {
|
|
(*ep->function)(p1, p2, flags);
|
|
ep = ep->next;
|
|
}
|
|
|
|
/*
|
|
* Make child runnable and add to run queue.
|
|
*/
|
|
microtime(&(p2->p_stats->p_start));
|
|
p2->p_acflag = AFORK;
|
|
(void) splhigh();
|
|
p2->p_stat = SRUN;
|
|
setrunqueue(p2);
|
|
(void) spl0();
|
|
|
|
/*
|
|
* Now can be swapped.
|
|
*/
|
|
p1->p_flag &= ~P_NOSWAP;
|
|
|
|
/*
|
|
* Preserve synchronization semantics of vfork. If waiting for
|
|
* child to exec or exit, set P_PPWAIT on child, and sleep on our
|
|
* proc (in case of exit).
|
|
*/
|
|
while (p2->p_flag & P_PPWAIT)
|
|
tsleep(p1, PWAIT, "ppwait", 0);
|
|
|
|
/*
|
|
* Return child pid to parent process,
|
|
* marking us as parent via retval[1].
|
|
*/
|
|
retval[0] = p2->p_pid;
|
|
retval[1] = 0;
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* The next two functionms are general routines to handle adding/deleting
|
|
* items on the fork callout list.
|
|
*
|
|
* at_fork():
|
|
* Take the arguments given and put them onto the fork callout list,
|
|
* However first make sure that it's not already there.
|
|
* Returns 0 on success or a standard error number.
|
|
*/
|
|
int
|
|
at_fork(forklist_fn function)
|
|
{
|
|
fle_p ep;
|
|
|
|
/* let the programmer know if he's been stupid */
|
|
if (rm_at_fork(function))
|
|
printf("fork callout entry already present\n");
|
|
ep = malloc(sizeof(*ep), M_TEMP, M_NOWAIT);
|
|
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(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);
|
|
}
|
|
|
|
|