freebsd-dev/sys/kern/kern_fork.c
Julian Elischer 4ac9ae7083 Fix thread/process tracking and differentiation for Linux threads emulation.
Submitted by:	Richard Seaman, Jr." <dick@tar.com>

Also clean some compiler warnings in surrounding code.
1999-03-02 00:28:09 +00:00

546 lines
14 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 1.55 1999/01/26 02:38:10 julian 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 <sys/lock.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_extern.h>
#include <vm/vm_zone.h>
#include <machine/frame.h>
#include <sys/user.h>
#ifdef SMP
static int fast_vfork = 0; /* Doesn't work on SMP yet. */
#else
static int fast_vfork = 1;
#endif
SYSCTL_INT(_kern, OID_AUTO, fast_vfork, CTLFLAG_RW, &fast_vfork, 0, "");
/*
* 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)
struct proc *p;
struct fork_args *uap;
{
return (fork1(p, RFFDG | RFPROC));
}
/* ARGSUSED */
int
vfork(p, uap)
struct proc *p;
struct vfork_args *uap;
{
return (fork1(p, RFFDG | RFPROC | RFPPWAIT | (fast_vfork ? RFMEM : 0)));
}
/* ARGSUSED */
int
rfork(p, uap)
struct proc *p;
struct rfork_args *uap;
{
return (fork1(p, uap->flags));
}
int nprocs = 1; /* process 0 */
static int nextpid = 0;
int
fork1(p1, flags)
register struct proc *p1;
int flags;
{
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. */
newproc = zalloc(proc_zone);
/*
* 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 ||
p2->p_session->s_sid == 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 (p2->p_session->s_sid > nextpid &&
pidchecked > p2->p_session->s_sid)
pidchecked = p2->p_session->s_sid;
}
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);
if (flags & RFSIGSHARE) {
p2->p_procsig = p1->p_procsig;
p2->p_procsig->ps_refcnt++;
if (p1->p_sigacts == &p1->p_addr->u_sigacts) {
struct sigacts *newsigacts;
int s;
if (p2->p_procsig->ps_refcnt != 2)
printf ("PID:%d Creating shared sigacts with procsig->ps_refcnt %d\n",
p2->p_pid, p2->p_procsig->ps_refcnt);
/* Create the shared sigacts structure */
MALLOC (newsigacts, struct sigacts *, sizeof (struct sigacts),
M_SUBPROC, M_WAITOK);
s = splhigh();
/* Set p_sigacts to the new shared structure. Note that this
* is updating p1->p_sigacts at the same time, since p_sigacts
* is just a pointer to the shared p_procsig->ps_sigacts.
*/
p2->p_sigacts = newsigacts;
/* Copy in the values from the u area */
*p2->p_sigacts = p1->p_addr->u_sigacts;
splx (s);
}
} else {
MALLOC (p2->p_procsig, struct procsig *, sizeof(struct procsig),
M_SUBPROC, M_WAITOK);
bcopy(&p1->p_procsig->ps_begincopy, &p2->p_procsig->ps_begincopy,
(unsigned)&p1->p_procsig->ps_endcopy -
(unsigned)&p1->p_procsig->ps_begincopy);
p2->p_procsig->ps_refcnt = 1;
/* Note that we fill in the values of sigacts in vm_fork */
p2->p_sigacts = NULL;
}
if (flags & RFLINUXTHPN)
p2->p_sigparent = SIGUSR1;
else
p2->p_sigparent = SIGCHLD;
/* 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 more flags in subprocess. P_PROFIL has already
* been preserved.
*/
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 p1->p_retval[1].
*/
p1->p_retval[0] = p2->p_pid;
p1->p_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(function)
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(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);
}