Doing so removes the dependency on proctree lock from sysctl process list export which further reduces contention during poudriere -j 128 runs. Reviewed by: kib (previous version) Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D17825
1126 lines
28 KiB
C
1126 lines
28 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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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. 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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*/
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#include <sys/cdefs.h>
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|
__FBSDID("$FreeBSD$");
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|
|
|
#include "opt_ktrace.h"
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|
#include "opt_kstack_pages.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/eventhandler.h>
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|
#include <sys/fcntl.h>
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|
#include <sys/filedesc.h>
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|
#include <sys/jail.h>
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|
#include <sys/kernel.h>
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|
#include <sys/kthread.h>
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|
#include <sys/sysctl.h>
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|
#include <sys/lock.h>
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|
#include <sys/malloc.h>
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|
#include <sys/mutex.h>
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|
#include <sys/priv.h>
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|
#include <sys/proc.h>
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|
#include <sys/procdesc.h>
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|
#include <sys/pioctl.h>
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|
#include <sys/ptrace.h>
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|
#include <sys/racct.h>
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|
#include <sys/resourcevar.h>
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|
#include <sys/sched.h>
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|
#include <sys/syscall.h>
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|
#include <sys/vmmeter.h>
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|
#include <sys/vnode.h>
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|
#include <sys/acct.h>
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|
#include <sys/ktr.h>
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|
#include <sys/ktrace.h>
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|
#include <sys/unistd.h>
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|
#include <sys/sdt.h>
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|
#include <sys/sx.h>
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|
#include <sys/sysent.h>
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|
#include <sys/signalvar.h>
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|
|
|
#include <security/audit/audit.h>
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|
#include <security/mac/mac_framework.h>
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|
|
|
#include <vm/vm.h>
|
|
#include <vm/pmap.h>
|
|
#include <vm/vm_map.h>
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|
#include <vm/vm_extern.h>
|
|
#include <vm/uma.h>
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|
|
|
#ifdef KDTRACE_HOOKS
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|
#include <sys/dtrace_bsd.h>
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|
dtrace_fork_func_t dtrace_fasttrap_fork;
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|
#endif
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|
|
|
SDT_PROVIDER_DECLARE(proc);
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|
SDT_PROBE_DEFINE3(proc, , , create, "struct proc *", "struct proc *", "int");
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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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|
#endif
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|
|
|
EVENTHANDLER_LIST_DECLARE(process_fork);
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|
|
|
/* ARGSUSED */
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|
int
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|
sys_fork(struct thread *td, struct fork_args *uap)
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|
{
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|
struct fork_req fr;
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|
int error, pid;
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|
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|
bzero(&fr, sizeof(fr));
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fr.fr_flags = RFFDG | RFPROC;
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fr.fr_pidp = &pid;
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error = fork1(td, &fr);
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|
if (error == 0) {
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td->td_retval[0] = pid;
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|
td->td_retval[1] = 0;
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|
}
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|
return (error);
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|
}
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|
|
|
/* ARGUSED */
|
|
int
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|
sys_pdfork(struct thread *td, struct pdfork_args *uap)
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|
{
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|
struct fork_req fr;
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|
int error, fd, pid;
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|
|
|
bzero(&fr, sizeof(fr));
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fr.fr_flags = RFFDG | RFPROC | RFPROCDESC;
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fr.fr_pidp = &pid;
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fr.fr_pd_fd = &fd;
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|
fr.fr_pd_flags = uap->flags;
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|
/*
|
|
* It is necessary to return fd by reference because 0 is a valid file
|
|
* descriptor number, and the child needs to be able to distinguish
|
|
* itself from the parent using the return value.
|
|
*/
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|
error = fork1(td, &fr);
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|
if (error == 0) {
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|
td->td_retval[0] = pid;
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|
td->td_retval[1] = 0;
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|
error = copyout(&fd, uap->fdp, sizeof(fd));
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|
}
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|
return (error);
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|
}
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|
|
|
/* ARGSUSED */
|
|
int
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|
sys_vfork(struct thread *td, struct vfork_args *uap)
|
|
{
|
|
struct fork_req fr;
|
|
int error, pid;
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|
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|
bzero(&fr, sizeof(fr));
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|
fr.fr_flags = RFFDG | RFPROC | RFPPWAIT | RFMEM;
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|
fr.fr_pidp = &pid;
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|
error = fork1(td, &fr);
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|
if (error == 0) {
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|
td->td_retval[0] = pid;
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|
td->td_retval[1] = 0;
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|
}
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|
return (error);
|
|
}
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|
|
|
int
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|
sys_rfork(struct thread *td, struct rfork_args *uap)
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|
{
|
|
struct fork_req fr;
|
|
int error, pid;
|
|
|
|
/* Don't allow kernel-only flags. */
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|
if ((uap->flags & RFKERNELONLY) != 0)
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|
return (EINVAL);
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|
|
|
AUDIT_ARG_FFLAGS(uap->flags);
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|
bzero(&fr, sizeof(fr));
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|
fr.fr_flags = uap->flags;
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|
fr.fr_pidp = &pid;
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|
error = fork1(td, &fr);
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|
if (error == 0) {
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|
td->td_retval[0] = pid;
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|
td->td_retval[1] = 0;
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|
}
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|
return (error);
|
|
}
|
|
|
|
int nprocs = 1; /* process 0 */
|
|
int lastpid = 0;
|
|
SYSCTL_INT(_kern, OID_AUTO, lastpid, CTLFLAG_RD, &lastpid, 0,
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|
"Last used PID");
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|
|
|
/*
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|
* Random component to lastpid generation. We mix in a random factor to make
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|
* it a little harder to predict. We sanity check the modulus value to avoid
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|
* doing it in critical paths. Don't let it be too small or we pointlessly
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* waste randomness entropy, and don't let it be impossibly large. Using a
|
|
* modulus that is too big causes a LOT more process table scans and slows
|
|
* down fork processing as the pidchecked caching is defeated.
|
|
*/
|
|
static int randompid = 0;
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|
|
|
static int
|
|
sysctl_kern_randompid(SYSCTL_HANDLER_ARGS)
|
|
{
|
|
int error, pid;
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|
|
|
error = sysctl_wire_old_buffer(req, sizeof(int));
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|
if (error != 0)
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|
return(error);
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|
sx_xlock(&allproc_lock);
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pid = randompid;
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|
error = sysctl_handle_int(oidp, &pid, 0, req);
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|
if (error == 0 && req->newptr != NULL) {
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|
if (pid == 0)
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|
randompid = 0;
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|
else if (pid == 1)
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|
/* generate a random PID modulus between 100 and 1123 */
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|
randompid = 100 + arc4random() % 1024;
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|
else if (pid < 0 || pid > pid_max - 100)
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|
/* out of range */
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|
randompid = pid_max - 100;
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|
else if (pid < 100)
|
|
/* Make it reasonable */
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|
randompid = 100;
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else
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randompid = pid;
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}
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sx_xunlock(&allproc_lock);
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return (error);
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|
}
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|
SYSCTL_PROC(_kern, OID_AUTO, randompid, CTLTYPE_INT|CTLFLAG_RW,
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0, 0, sysctl_kern_randompid, "I", "Random PID modulus. Special values: 0: disable, 1: choose random value");
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|
|
static int
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|
fork_findpid(int flags)
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|
{
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|
struct proc *p;
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|
int trypid;
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|
static int pidchecked = 0;
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|
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|
/*
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* Requires allproc_lock in order to iterate over the list
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* of processes, and proctree_lock to access p_pgrp.
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|
*/
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|
sx_assert(&allproc_lock, SX_LOCKED);
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|
sx_assert(&proctree_lock, SX_LOCKED);
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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 lastpid+1 through pidchecked-1).
|
|
*
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|
* If RFHIGHPID is set (used during system boot), do not allocate
|
|
* low-numbered pids.
|
|
*/
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|
trypid = lastpid + 1;
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|
if (flags & RFHIGHPID) {
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|
if (trypid < 10)
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|
trypid = 10;
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|
} else {
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if (randompid)
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|
trypid += arc4random() % randompid;
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|
}
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|
retry:
|
|
/*
|
|
* 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.
|
|
*/
|
|
if (trypid >= pid_max) {
|
|
trypid = trypid % pid_max;
|
|
if (trypid < 100)
|
|
trypid += 100;
|
|
pidchecked = 0;
|
|
}
|
|
if (trypid >= 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 trypid, so we can avoid checking for a while.
|
|
*
|
|
* Avoid reuse of the process group id, session id or
|
|
* the reaper subtree id. Note that for process group
|
|
* and sessions, the amount of reserved pids is
|
|
* limited by process limit. For the subtree ids, the
|
|
* id is kept reserved only while there is a
|
|
* non-reaped process in the subtree, so amount of
|
|
* reserved pids is limited by process limit times
|
|
* two.
|
|
*/
|
|
p = LIST_FIRST(&allproc);
|
|
again:
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|
for (; p != NULL; p = LIST_NEXT(p, p_list)) {
|
|
while (p->p_pid == trypid ||
|
|
p->p_reapsubtree == trypid ||
|
|
(p->p_pgrp != NULL &&
|
|
(p->p_pgrp->pg_id == trypid ||
|
|
(p->p_session != NULL &&
|
|
p->p_session->s_sid == trypid)))) {
|
|
trypid++;
|
|
if (trypid >= pidchecked)
|
|
goto retry;
|
|
}
|
|
if (p->p_pid > trypid && pidchecked > p->p_pid)
|
|
pidchecked = p->p_pid;
|
|
if (p->p_pgrp != NULL) {
|
|
if (p->p_pgrp->pg_id > trypid &&
|
|
pidchecked > p->p_pgrp->pg_id)
|
|
pidchecked = p->p_pgrp->pg_id;
|
|
if (p->p_session != NULL &&
|
|
p->p_session->s_sid > trypid &&
|
|
pidchecked > p->p_session->s_sid)
|
|
pidchecked = p->p_session->s_sid;
|
|
}
|
|
}
|
|
if (!doingzomb) {
|
|
doingzomb = 1;
|
|
p = LIST_FIRST(&zombproc);
|
|
goto again;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* RFHIGHPID does not mess with the lastpid counter during boot.
|
|
*/
|
|
if (flags & RFHIGHPID)
|
|
pidchecked = 0;
|
|
else
|
|
lastpid = trypid;
|
|
|
|
return (trypid);
|
|
}
|
|
|
|
static int
|
|
fork_norfproc(struct thread *td, int flags)
|
|
{
|
|
int error;
|
|
struct proc *p1;
|
|
|
|
KASSERT((flags & RFPROC) == 0,
|
|
("fork_norfproc called with RFPROC set"));
|
|
p1 = td->td_proc;
|
|
|
|
if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) &&
|
|
(flags & (RFCFDG | RFFDG))) {
|
|
PROC_LOCK(p1);
|
|
if (thread_single(p1, SINGLE_BOUNDARY)) {
|
|
PROC_UNLOCK(p1);
|
|
return (ERESTART);
|
|
}
|
|
PROC_UNLOCK(p1);
|
|
}
|
|
|
|
error = vm_forkproc(td, NULL, NULL, NULL, flags);
|
|
if (error)
|
|
goto fail;
|
|
|
|
/*
|
|
* Close all file descriptors.
|
|
*/
|
|
if (flags & RFCFDG) {
|
|
struct filedesc *fdtmp;
|
|
fdtmp = fdinit(td->td_proc->p_fd, false);
|
|
fdescfree(td);
|
|
p1->p_fd = fdtmp;
|
|
}
|
|
|
|
/*
|
|
* Unshare file descriptors (from parent).
|
|
*/
|
|
if (flags & RFFDG)
|
|
fdunshare(td);
|
|
|
|
fail:
|
|
if (((p1->p_flag & (P_HADTHREADS|P_SYSTEM)) == P_HADTHREADS) &&
|
|
(flags & (RFCFDG | RFFDG))) {
|
|
PROC_LOCK(p1);
|
|
thread_single_end(p1, SINGLE_BOUNDARY);
|
|
PROC_UNLOCK(p1);
|
|
}
|
|
return (error);
|
|
}
|
|
|
|
static void
|
|
do_fork(struct thread *td, struct fork_req *fr, struct proc *p2, struct thread *td2,
|
|
struct vmspace *vm2, struct file *fp_procdesc)
|
|
{
|
|
struct proc *p1, *pptr;
|
|
int trypid;
|
|
struct filedesc *fd;
|
|
struct filedesc_to_leader *fdtol;
|
|
struct sigacts *newsigacts;
|
|
|
|
sx_assert(&proctree_lock, SX_LOCKED);
|
|
sx_assert(&allproc_lock, SX_XLOCKED);
|
|
|
|
p1 = td->td_proc;
|
|
|
|
trypid = fork_findpid(fr->fr_flags);
|
|
|
|
p2->p_state = PRS_NEW; /* protect against others */
|
|
p2->p_pid = trypid;
|
|
AUDIT_ARG_PID(p2->p_pid);
|
|
LIST_INSERT_HEAD(&allproc, p2, p_list);
|
|
allproc_gen++;
|
|
LIST_INSERT_HEAD(PIDHASH(p2->p_pid), p2, p_hash);
|
|
PROC_LOCK(p2);
|
|
PROC_LOCK(p1);
|
|
|
|
sx_xunlock(&allproc_lock);
|
|
sx_xunlock(&proctree_lock);
|
|
|
|
bcopy(&p1->p_startcopy, &p2->p_startcopy,
|
|
__rangeof(struct proc, p_startcopy, p_endcopy));
|
|
pargs_hold(p2->p_args);
|
|
|
|
PROC_UNLOCK(p1);
|
|
|
|
bzero(&p2->p_startzero,
|
|
__rangeof(struct proc, p_startzero, p_endzero));
|
|
|
|
/* Tell the prison that we exist. */
|
|
prison_proc_hold(p2->p_ucred->cr_prison);
|
|
|
|
PROC_UNLOCK(p2);
|
|
|
|
tidhash_add(td2);
|
|
|
|
/*
|
|
* Malloc things while we don't hold any locks.
|
|
*/
|
|
if (fr->fr_flags & RFSIGSHARE)
|
|
newsigacts = NULL;
|
|
else
|
|
newsigacts = sigacts_alloc();
|
|
|
|
/*
|
|
* Copy filedesc.
|
|
*/
|
|
if (fr->fr_flags & RFCFDG) {
|
|
fd = fdinit(p1->p_fd, false);
|
|
fdtol = NULL;
|
|
} else if (fr->fr_flags & RFFDG) {
|
|
fd = fdcopy(p1->p_fd);
|
|
fdtol = NULL;
|
|
} else {
|
|
fd = fdshare(p1->p_fd);
|
|
if (p1->p_fdtol == NULL)
|
|
p1->p_fdtol = filedesc_to_leader_alloc(NULL, NULL,
|
|
p1->p_leader);
|
|
if ((fr->fr_flags & RFTHREAD) != 0) {
|
|
/*
|
|
* Shared file descriptor table, and shared
|
|
* process leaders.
|
|
*/
|
|
fdtol = p1->p_fdtol;
|
|
FILEDESC_XLOCK(p1->p_fd);
|
|
fdtol->fdl_refcount++;
|
|
FILEDESC_XUNLOCK(p1->p_fd);
|
|
} else {
|
|
/*
|
|
* Shared file descriptor table, and different
|
|
* process leaders.
|
|
*/
|
|
fdtol = filedesc_to_leader_alloc(p1->p_fdtol,
|
|
p1->p_fd, p2);
|
|
}
|
|
}
|
|
/*
|
|
* 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.
|
|
*/
|
|
|
|
PROC_LOCK(p2);
|
|
PROC_LOCK(p1);
|
|
|
|
bzero(&td2->td_startzero,
|
|
__rangeof(struct thread, td_startzero, td_endzero));
|
|
|
|
bcopy(&td->td_startcopy, &td2->td_startcopy,
|
|
__rangeof(struct thread, td_startcopy, td_endcopy));
|
|
|
|
bcopy(&p2->p_comm, &td2->td_name, sizeof(td2->td_name));
|
|
td2->td_sigstk = td->td_sigstk;
|
|
td2->td_flags = TDF_INMEM;
|
|
td2->td_lend_user_pri = PRI_MAX;
|
|
|
|
#ifdef VIMAGE
|
|
td2->td_vnet = NULL;
|
|
td2->td_vnet_lpush = NULL;
|
|
#endif
|
|
|
|
/*
|
|
* Allow the scheduler to initialize the child.
|
|
*/
|
|
thread_lock(td);
|
|
sched_fork(td, td2);
|
|
thread_unlock(td);
|
|
|
|
/*
|
|
* Duplicate sub-structures as needed.
|
|
* Increase reference counts on shared objects.
|
|
*/
|
|
p2->p_flag = P_INMEM;
|
|
p2->p_flag2 = p1->p_flag2 & (P2_NOTRACE | P2_NOTRACE_EXEC | P2_TRAPCAP);
|
|
p2->p_swtick = ticks;
|
|
if (p1->p_flag & P_PROFIL)
|
|
startprofclock(p2);
|
|
|
|
if (fr->fr_flags & RFSIGSHARE) {
|
|
p2->p_sigacts = sigacts_hold(p1->p_sigacts);
|
|
} else {
|
|
sigacts_copy(newsigacts, p1->p_sigacts);
|
|
p2->p_sigacts = newsigacts;
|
|
}
|
|
|
|
if (fr->fr_flags & RFTSIGZMB)
|
|
p2->p_sigparent = RFTSIGNUM(fr->fr_flags);
|
|
else if (fr->fr_flags & RFLINUXTHPN)
|
|
p2->p_sigparent = SIGUSR1;
|
|
else
|
|
p2->p_sigparent = SIGCHLD;
|
|
|
|
p2->p_textvp = p1->p_textvp;
|
|
p2->p_fd = fd;
|
|
p2->p_fdtol = fdtol;
|
|
|
|
if (p1->p_flag2 & P2_INHERIT_PROTECTED) {
|
|
p2->p_flag |= P_PROTECTED;
|
|
p2->p_flag2 |= P2_INHERIT_PROTECTED;
|
|
}
|
|
|
|
/*
|
|
* p_limit is copy-on-write. Bump its refcount.
|
|
*/
|
|
lim_fork(p1, p2);
|
|
|
|
thread_cow_get_proc(td2, p2);
|
|
|
|
pstats_fork(p1->p_stats, p2->p_stats);
|
|
|
|
PROC_UNLOCK(p1);
|
|
PROC_UNLOCK(p2);
|
|
|
|
/* Bump references to the text vnode (for procfs). */
|
|
if (p2->p_textvp)
|
|
vrefact(p2->p_textvp);
|
|
|
|
/*
|
|
* Set up linkage for kernel based threading.
|
|
*/
|
|
if ((fr->fr_flags & RFTHREAD) != 0) {
|
|
mtx_lock(&ppeers_lock);
|
|
p2->p_peers = p1->p_peers;
|
|
p1->p_peers = p2;
|
|
p2->p_leader = p1->p_leader;
|
|
mtx_unlock(&ppeers_lock);
|
|
PROC_LOCK(p1->p_leader);
|
|
if ((p1->p_leader->p_flag & P_WEXIT) != 0) {
|
|
PROC_UNLOCK(p1->p_leader);
|
|
/*
|
|
* The task leader is exiting, so process p1 is
|
|
* going to be killed shortly. Since p1 obviously
|
|
* isn't dead yet, we know that the leader is either
|
|
* sending SIGKILL's to all the processes in this
|
|
* task or is sleeping waiting for all the peers to
|
|
* exit. We let p1 complete the fork, but we need
|
|
* to go ahead and kill the new process p2 since
|
|
* the task leader may not get a chance to send
|
|
* SIGKILL to it. We leave it on the list so that
|
|
* the task leader will wait for this new process
|
|
* to commit suicide.
|
|
*/
|
|
PROC_LOCK(p2);
|
|
kern_psignal(p2, SIGKILL);
|
|
PROC_UNLOCK(p2);
|
|
} else
|
|
PROC_UNLOCK(p1->p_leader);
|
|
} else {
|
|
p2->p_peers = NULL;
|
|
p2->p_leader = p2;
|
|
}
|
|
|
|
sx_xlock(&proctree_lock);
|
|
PGRP_LOCK(p1->p_pgrp);
|
|
PROC_LOCK(p2);
|
|
PROC_LOCK(p1);
|
|
|
|
/*
|
|
* Preserve some more flags in subprocess. P_PROFIL has already
|
|
* been preserved.
|
|
*/
|
|
p2->p_flag |= p1->p_flag & P_SUGID;
|
|
td2->td_pflags |= (td->td_pflags & TDP_ALTSTACK) | TDP_FORKING;
|
|
SESS_LOCK(p1->p_session);
|
|
if (p1->p_session->s_ttyvp != NULL && p1->p_flag & P_CONTROLT)
|
|
p2->p_flag |= P_CONTROLT;
|
|
SESS_UNLOCK(p1->p_session);
|
|
if (fr->fr_flags & RFPPWAIT)
|
|
p2->p_flag |= P_PPWAIT;
|
|
|
|
p2->p_pgrp = p1->p_pgrp;
|
|
LIST_INSERT_AFTER(p1, p2, p_pglist);
|
|
PGRP_UNLOCK(p1->p_pgrp);
|
|
LIST_INIT(&p2->p_children);
|
|
LIST_INIT(&p2->p_orphans);
|
|
|
|
callout_init_mtx(&p2->p_itcallout, &p2->p_mtx, 0);
|
|
|
|
/*
|
|
* If PF_FORK is set, the child process inherits the
|
|
* procfs ioctl flags from its parent.
|
|
*/
|
|
if (p1->p_pfsflags & PF_FORK) {
|
|
p2->p_stops = p1->p_stops;
|
|
p2->p_pfsflags = p1->p_pfsflags;
|
|
}
|
|
|
|
/*
|
|
* This begins the section where we must prevent the parent
|
|
* from being swapped.
|
|
*/
|
|
_PHOLD(p1);
|
|
PROC_UNLOCK(p1);
|
|
|
|
/*
|
|
* 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 ((fr->fr_flags & RFNOWAIT) != 0) {
|
|
pptr = p1->p_reaper;
|
|
p2->p_reaper = pptr;
|
|
} else {
|
|
p2->p_reaper = (p1->p_treeflag & P_TREE_REAPER) != 0 ?
|
|
p1 : p1->p_reaper;
|
|
pptr = p1;
|
|
}
|
|
p2->p_pptr = pptr;
|
|
p2->p_oppid = pptr->p_pid;
|
|
LIST_INSERT_HEAD(&pptr->p_children, p2, p_sibling);
|
|
LIST_INIT(&p2->p_reaplist);
|
|
LIST_INSERT_HEAD(&p2->p_reaper->p_reaplist, p2, p_reapsibling);
|
|
if (p2->p_reaper == p1)
|
|
p2->p_reapsubtree = p2->p_pid;
|
|
sx_xunlock(&proctree_lock);
|
|
|
|
/* Inform accounting that we have forked. */
|
|
p2->p_acflag = AFORK;
|
|
PROC_UNLOCK(p2);
|
|
|
|
#ifdef KTRACE
|
|
ktrprocfork(p1, p2);
|
|
#endif
|
|
|
|
/*
|
|
* Finish creating the child process. It will return via a different
|
|
* execution path later. (ie: directly into user mode)
|
|
*/
|
|
vm_forkproc(td, p2, td2, vm2, fr->fr_flags);
|
|
|
|
if (fr->fr_flags == (RFFDG | RFPROC)) {
|
|
VM_CNT_INC(v_forks);
|
|
VM_CNT_ADD(v_forkpages, p2->p_vmspace->vm_dsize +
|
|
p2->p_vmspace->vm_ssize);
|
|
} else if (fr->fr_flags == (RFFDG | RFPROC | RFPPWAIT | RFMEM)) {
|
|
VM_CNT_INC(v_vforks);
|
|
VM_CNT_ADD(v_vforkpages, p2->p_vmspace->vm_dsize +
|
|
p2->p_vmspace->vm_ssize);
|
|
} else if (p1 == &proc0) {
|
|
VM_CNT_INC(v_kthreads);
|
|
VM_CNT_ADD(v_kthreadpages, p2->p_vmspace->vm_dsize +
|
|
p2->p_vmspace->vm_ssize);
|
|
} else {
|
|
VM_CNT_INC(v_rforks);
|
|
VM_CNT_ADD(v_rforkpages, p2->p_vmspace->vm_dsize +
|
|
p2->p_vmspace->vm_ssize);
|
|
}
|
|
|
|
/*
|
|
* Associate the process descriptor with the process before anything
|
|
* can happen that might cause that process to need the descriptor.
|
|
* However, don't do this until after fork(2) can no longer fail.
|
|
*/
|
|
if (fr->fr_flags & RFPROCDESC)
|
|
procdesc_new(p2, fr->fr_pd_flags);
|
|
|
|
/*
|
|
* Both processes are set up, now check if any loadable modules want
|
|
* to adjust anything.
|
|
*/
|
|
EVENTHANDLER_DIRECT_INVOKE(process_fork, p1, p2, fr->fr_flags);
|
|
|
|
/*
|
|
* Set the child start time and mark the process as being complete.
|
|
*/
|
|
PROC_LOCK(p2);
|
|
PROC_LOCK(p1);
|
|
microuptime(&p2->p_stats->p_start);
|
|
PROC_SLOCK(p2);
|
|
p2->p_state = PRS_NORMAL;
|
|
PROC_SUNLOCK(p2);
|
|
|
|
#ifdef KDTRACE_HOOKS
|
|
/*
|
|
* Tell the DTrace fasttrap provider about the new process so that any
|
|
* tracepoints inherited from the parent can be removed. We have to do
|
|
* this only after p_state is PRS_NORMAL since the fasttrap module will
|
|
* use pfind() later on.
|
|
*/
|
|
if ((fr->fr_flags & RFMEM) == 0 && dtrace_fasttrap_fork)
|
|
dtrace_fasttrap_fork(p1, p2);
|
|
#endif
|
|
/*
|
|
* Hold the process so that it cannot exit after we make it runnable,
|
|
* but before we wait for the debugger.
|
|
*/
|
|
_PHOLD(p2);
|
|
if (fr->fr_flags & RFPPWAIT) {
|
|
td->td_pflags |= TDP_RFPPWAIT;
|
|
td->td_rfppwait_p = p2;
|
|
td->td_dbgflags |= TDB_VFORK;
|
|
}
|
|
PROC_UNLOCK(p2);
|
|
|
|
/*
|
|
* Now can be swapped.
|
|
*/
|
|
_PRELE(p1);
|
|
PROC_UNLOCK(p1);
|
|
|
|
/*
|
|
* Tell any interested parties about the new process.
|
|
*/
|
|
knote_fork(p1->p_klist, p2->p_pid);
|
|
SDT_PROBE3(proc, , , create, p2, p1, fr->fr_flags);
|
|
|
|
if (fr->fr_flags & RFPROCDESC) {
|
|
procdesc_finit(p2->p_procdesc, fp_procdesc);
|
|
fdrop(fp_procdesc, td);
|
|
}
|
|
|
|
/*
|
|
* Speculative check for PTRACE_FORK. PTRACE_FORK is not
|
|
* synced with forks in progress so it is OK if we miss it
|
|
* if being set atm.
|
|
*/
|
|
if ((p1->p_ptevents & PTRACE_FORK) != 0) {
|
|
sx_xlock(&proctree_lock);
|
|
PROC_LOCK(p2);
|
|
|
|
/*
|
|
* p1->p_ptevents & p1->p_pptr are protected by both
|
|
* process and proctree locks for modifications,
|
|
* so owning proctree_lock allows the race-free read.
|
|
*/
|
|
if ((p1->p_ptevents & PTRACE_FORK) != 0) {
|
|
/*
|
|
* Arrange for debugger to receive the fork event.
|
|
*
|
|
* We can report PL_FLAG_FORKED regardless of
|
|
* P_FOLLOWFORK settings, but it does not make a sense
|
|
* for runaway child.
|
|
*/
|
|
td->td_dbgflags |= TDB_FORK;
|
|
td->td_dbg_forked = p2->p_pid;
|
|
td2->td_dbgflags |= TDB_STOPATFORK;
|
|
proc_set_traced(p2, true);
|
|
CTR2(KTR_PTRACE,
|
|
"do_fork: attaching to new child pid %d: oppid %d",
|
|
p2->p_pid, p2->p_oppid);
|
|
proc_reparent(p2, p1->p_pptr, false);
|
|
}
|
|
PROC_UNLOCK(p2);
|
|
sx_xunlock(&proctree_lock);
|
|
}
|
|
|
|
if ((fr->fr_flags & RFSTOPPED) == 0) {
|
|
/*
|
|
* If RFSTOPPED not requested, make child runnable and
|
|
* add to run queue.
|
|
*/
|
|
thread_lock(td2);
|
|
TD_SET_CAN_RUN(td2);
|
|
sched_add(td2, SRQ_BORING);
|
|
thread_unlock(td2);
|
|
if (fr->fr_pidp != NULL)
|
|
*fr->fr_pidp = p2->p_pid;
|
|
} else {
|
|
*fr->fr_procp = p2;
|
|
}
|
|
|
|
PROC_LOCK(p2);
|
|
_PRELE(p2);
|
|
racct_proc_fork_done(p2);
|
|
PROC_UNLOCK(p2);
|
|
}
|
|
|
|
int
|
|
fork1(struct thread *td, struct fork_req *fr)
|
|
{
|
|
struct proc *p1, *newproc;
|
|
struct thread *td2;
|
|
struct vmspace *vm2;
|
|
struct file *fp_procdesc;
|
|
vm_ooffset_t mem_charged;
|
|
int error, nprocs_new, ok;
|
|
static int curfail;
|
|
static struct timeval lastfail;
|
|
int flags, pages;
|
|
|
|
flags = fr->fr_flags;
|
|
pages = fr->fr_pages;
|
|
|
|
if ((flags & RFSTOPPED) != 0)
|
|
MPASS(fr->fr_procp != NULL && fr->fr_pidp == NULL);
|
|
else
|
|
MPASS(fr->fr_procp == NULL);
|
|
|
|
/* Check for the undefined or unimplemented flags. */
|
|
if ((flags & ~(RFFLAGS | RFTSIGFLAGS(RFTSIGMASK))) != 0)
|
|
return (EINVAL);
|
|
|
|
/* Signal value requires RFTSIGZMB. */
|
|
if ((flags & RFTSIGFLAGS(RFTSIGMASK)) != 0 && (flags & RFTSIGZMB) == 0)
|
|
return (EINVAL);
|
|
|
|
/* Can't copy and clear. */
|
|
if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
|
|
return (EINVAL);
|
|
|
|
/* Check the validity of the signal number. */
|
|
if ((flags & RFTSIGZMB) != 0 && (u_int)RFTSIGNUM(flags) > _SIG_MAXSIG)
|
|
return (EINVAL);
|
|
|
|
if ((flags & RFPROCDESC) != 0) {
|
|
/* Can't not create a process yet get a process descriptor. */
|
|
if ((flags & RFPROC) == 0)
|
|
return (EINVAL);
|
|
|
|
/* Must provide a place to put a procdesc if creating one. */
|
|
if (fr->fr_pd_fd == NULL)
|
|
return (EINVAL);
|
|
|
|
/* Check if we are using supported flags. */
|
|
if ((fr->fr_pd_flags & ~PD_ALLOWED_AT_FORK) != 0)
|
|
return (EINVAL);
|
|
}
|
|
|
|
p1 = td->td_proc;
|
|
|
|
/*
|
|
* Here we don't create a new process, but we divorce
|
|
* certain parts of a process from itself.
|
|
*/
|
|
if ((flags & RFPROC) == 0) {
|
|
if (fr->fr_procp != NULL)
|
|
*fr->fr_procp = NULL;
|
|
else if (fr->fr_pidp != NULL)
|
|
*fr->fr_pidp = 0;
|
|
return (fork_norfproc(td, flags));
|
|
}
|
|
|
|
fp_procdesc = NULL;
|
|
newproc = NULL;
|
|
vm2 = NULL;
|
|
|
|
/*
|
|
* Increment the nprocs resource before allocations occur.
|
|
* Although process entries are dynamically created, we still
|
|
* keep a global limit on the maximum number we will
|
|
* create. There are hard-limits as to the number of processes
|
|
* that can run, established by the KVA and memory usage for
|
|
* the process data.
|
|
*
|
|
* Don't allow a nonprivileged user to use the last ten
|
|
* processes; don't let root exceed the limit.
|
|
*/
|
|
nprocs_new = atomic_fetchadd_int(&nprocs, 1) + 1;
|
|
if ((nprocs_new >= maxproc - 10 && priv_check_cred(td->td_ucred,
|
|
PRIV_MAXPROC, 0) != 0) || nprocs_new >= maxproc) {
|
|
error = EAGAIN;
|
|
sx_xlock(&allproc_lock);
|
|
if (ppsratecheck(&lastfail, &curfail, 1)) {
|
|
printf("maxproc limit exceeded by uid %u (pid %d); "
|
|
"see tuning(7) and login.conf(5)\n",
|
|
td->td_ucred->cr_ruid, p1->p_pid);
|
|
}
|
|
sx_xunlock(&allproc_lock);
|
|
goto fail2;
|
|
}
|
|
|
|
/*
|
|
* If required, create a process descriptor in the parent first; we
|
|
* will abandon it if something goes wrong. We don't finit() until
|
|
* later.
|
|
*/
|
|
if (flags & RFPROCDESC) {
|
|
error = procdesc_falloc(td, &fp_procdesc, fr->fr_pd_fd,
|
|
fr->fr_pd_flags, fr->fr_pd_fcaps);
|
|
if (error != 0)
|
|
goto fail2;
|
|
}
|
|
|
|
mem_charged = 0;
|
|
if (pages == 0)
|
|
pages = kstack_pages;
|
|
/* Allocate new proc. */
|
|
newproc = uma_zalloc(proc_zone, M_WAITOK);
|
|
td2 = FIRST_THREAD_IN_PROC(newproc);
|
|
if (td2 == NULL) {
|
|
td2 = thread_alloc(pages);
|
|
if (td2 == NULL) {
|
|
error = ENOMEM;
|
|
goto fail2;
|
|
}
|
|
proc_linkup(newproc, td2);
|
|
} else {
|
|
if (td2->td_kstack == 0 || td2->td_kstack_pages != pages) {
|
|
if (td2->td_kstack != 0)
|
|
vm_thread_dispose(td2);
|
|
if (!thread_alloc_stack(td2, pages)) {
|
|
error = ENOMEM;
|
|
goto fail2;
|
|
}
|
|
}
|
|
}
|
|
|
|
if ((flags & RFMEM) == 0) {
|
|
vm2 = vmspace_fork(p1->p_vmspace, &mem_charged);
|
|
if (vm2 == NULL) {
|
|
error = ENOMEM;
|
|
goto fail2;
|
|
}
|
|
if (!swap_reserve(mem_charged)) {
|
|
/*
|
|
* The swap reservation failed. The accounting
|
|
* from the entries of the copied vm2 will be
|
|
* subtracted in vmspace_free(), so force the
|
|
* reservation there.
|
|
*/
|
|
swap_reserve_force(mem_charged);
|
|
error = ENOMEM;
|
|
goto fail2;
|
|
}
|
|
} else
|
|
vm2 = NULL;
|
|
|
|
/*
|
|
* XXX: This is ugly; when we copy resource usage, we need to bump
|
|
* per-cred resource counters.
|
|
*/
|
|
proc_set_cred_init(newproc, crhold(td->td_ucred));
|
|
|
|
/*
|
|
* Initialize resource accounting for the child process.
|
|
*/
|
|
error = racct_proc_fork(p1, newproc);
|
|
if (error != 0) {
|
|
error = EAGAIN;
|
|
goto fail1;
|
|
}
|
|
|
|
#ifdef MAC
|
|
mac_proc_init(newproc);
|
|
#endif
|
|
newproc->p_klist = knlist_alloc(&newproc->p_mtx);
|
|
STAILQ_INIT(&newproc->p_ktr);
|
|
|
|
/* We have to lock the process tree while we look for a pid. */
|
|
sx_xlock(&proctree_lock);
|
|
sx_xlock(&allproc_lock);
|
|
|
|
/*
|
|
* Increment the count of procs running with this uid. Don't allow
|
|
* a nonprivileged user to exceed their current limit.
|
|
*
|
|
* XXXRW: Can we avoid privilege here if it's not needed?
|
|
*/
|
|
error = priv_check_cred(td->td_ucred, PRIV_PROC_LIMIT, 0);
|
|
if (error == 0)
|
|
ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1, 0);
|
|
else {
|
|
ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1,
|
|
lim_cur(td, RLIMIT_NPROC));
|
|
}
|
|
if (ok) {
|
|
do_fork(td, fr, newproc, td2, vm2, fp_procdesc);
|
|
return (0);
|
|
}
|
|
|
|
error = EAGAIN;
|
|
sx_xunlock(&allproc_lock);
|
|
sx_xunlock(&proctree_lock);
|
|
#ifdef MAC
|
|
mac_proc_destroy(newproc);
|
|
#endif
|
|
racct_proc_exit(newproc);
|
|
fail1:
|
|
crfree(newproc->p_ucred);
|
|
newproc->p_ucred = NULL;
|
|
fail2:
|
|
if (vm2 != NULL)
|
|
vmspace_free(vm2);
|
|
uma_zfree(proc_zone, newproc);
|
|
if ((flags & RFPROCDESC) != 0 && fp_procdesc != NULL) {
|
|
fdclose(td, fp_procdesc, *fr->fr_pd_fd);
|
|
fdrop(fp_procdesc, td);
|
|
}
|
|
atomic_add_int(&nprocs, -1);
|
|
pause("fork", hz / 2);
|
|
return (error);
|
|
}
|
|
|
|
/*
|
|
* Handle the return of a child process from fork1(). This function
|
|
* is called from the MD fork_trampoline() entry point.
|
|
*/
|
|
void
|
|
fork_exit(void (*callout)(void *, struct trapframe *), void *arg,
|
|
struct trapframe *frame)
|
|
{
|
|
struct proc *p;
|
|
struct thread *td;
|
|
struct thread *dtd;
|
|
|
|
td = curthread;
|
|
p = td->td_proc;
|
|
KASSERT(p->p_state == PRS_NORMAL, ("executing process is still new"));
|
|
|
|
CTR4(KTR_PROC, "fork_exit: new thread %p (td_sched %p, pid %d, %s)",
|
|
td, td_get_sched(td), p->p_pid, td->td_name);
|
|
|
|
sched_fork_exit(td);
|
|
/*
|
|
* Processes normally resume in mi_switch() after being
|
|
* cpu_switch()'ed to, but when children start up they arrive here
|
|
* instead, so we must do much the same things as mi_switch() would.
|
|
*/
|
|
if ((dtd = PCPU_GET(deadthread))) {
|
|
PCPU_SET(deadthread, NULL);
|
|
thread_stash(dtd);
|
|
}
|
|
thread_unlock(td);
|
|
|
|
/*
|
|
* cpu_fork_kthread_handler intercepts this function call to
|
|
* have this call a non-return function to stay in kernel mode.
|
|
* initproc has its own fork handler, but it does return.
|
|
*/
|
|
KASSERT(callout != NULL, ("NULL callout in fork_exit"));
|
|
callout(arg, frame);
|
|
|
|
/*
|
|
* Check if a kernel thread misbehaved and returned from its main
|
|
* function.
|
|
*/
|
|
if (p->p_flag & P_KPROC) {
|
|
printf("Kernel thread \"%s\" (pid %d) exited prematurely.\n",
|
|
td->td_name, p->p_pid);
|
|
kthread_exit();
|
|
}
|
|
mtx_assert(&Giant, MA_NOTOWNED);
|
|
|
|
if (p->p_sysent->sv_schedtail != NULL)
|
|
(p->p_sysent->sv_schedtail)(td);
|
|
td->td_pflags &= ~TDP_FORKING;
|
|
}
|
|
|
|
/*
|
|
* Simplified back end of syscall(), used when returning from fork()
|
|
* directly into user mode. This function is passed in to fork_exit()
|
|
* as the first parameter and is called when returning to a new
|
|
* userland process.
|
|
*/
|
|
void
|
|
fork_return(struct thread *td, struct trapframe *frame)
|
|
{
|
|
struct proc *p;
|
|
|
|
p = td->td_proc;
|
|
if (td->td_dbgflags & TDB_STOPATFORK) {
|
|
PROC_LOCK(p);
|
|
if ((p->p_flag & P_TRACED) != 0) {
|
|
/*
|
|
* Inform the debugger if one is still present.
|
|
*/
|
|
td->td_dbgflags |= TDB_CHILD | TDB_SCX | TDB_FSTP;
|
|
ptracestop(td, SIGSTOP, NULL);
|
|
td->td_dbgflags &= ~(TDB_CHILD | TDB_SCX);
|
|
} else {
|
|
/*
|
|
* ... otherwise clear the request.
|
|
*/
|
|
td->td_dbgflags &= ~TDB_STOPATFORK;
|
|
}
|
|
PROC_UNLOCK(p);
|
|
} else if (p->p_flag & P_TRACED || td->td_dbgflags & TDB_BORN) {
|
|
/*
|
|
* This is the start of a new thread in a traced
|
|
* process. Report a system call exit event.
|
|
*/
|
|
PROC_LOCK(p);
|
|
td->td_dbgflags |= TDB_SCX;
|
|
_STOPEVENT(p, S_SCX, td->td_sa.code);
|
|
if ((p->p_ptevents & PTRACE_SCX) != 0 ||
|
|
(td->td_dbgflags & TDB_BORN) != 0)
|
|
ptracestop(td, SIGTRAP, NULL);
|
|
td->td_dbgflags &= ~(TDB_SCX | TDB_BORN);
|
|
PROC_UNLOCK(p);
|
|
}
|
|
|
|
userret(td, frame);
|
|
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(td, KTR_SYSRET))
|
|
ktrsysret(SYS_fork, 0, 0);
|
|
#endif
|
|
}
|