507 lines
14 KiB
C
507 lines
14 KiB
C
/* $NetBSD: kern_fork.c,v 1.109 2003/06/29 22:31:20 fvdl Exp $ */
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/*-
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* Copyright (c) 1999, 2001 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
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* NASA Ames Research Center.
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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 NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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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. 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 8.8 (Berkeley) 2/14/95
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: kern_fork.c,v 1.109 2003/06/29 22:31:20 fvdl Exp $");
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#include "opt_ktrace.h"
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#include "opt_systrace.h"
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#include "opt_multiprocessor.h"
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#include <sys/param.h>
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#include <sys/systm.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/pool.h>
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#include <sys/mount.h>
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#include <sys/proc.h>
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#include <sys/ras.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 <sys/vmmeter.h>
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#include <sys/sched.h>
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#include <sys/signalvar.h>
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#include <sys/systrace.h>
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#include <sys/sa.h>
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#include <sys/syscallargs.h>
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#include <uvm/uvm_extern.h>
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int nprocs = 1; /* process 0 */
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/*
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* Number of ticks to sleep if fork() would fail due to process hitting
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* limits. Exported in miliseconds to userland via sysctl.
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*/
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int forkfsleep = 0;
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/*ARGSUSED*/
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int
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sys_fork(struct lwp *l, void *v, register_t *retval)
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{
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return (fork1(l, 0, SIGCHLD, NULL, 0, NULL, NULL, retval, NULL));
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}
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/*
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* vfork(2) system call compatible with 4.4BSD (i.e. BSD with Mach VM).
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* Address space is not shared, but parent is blocked until child exit.
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*/
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/*ARGSUSED*/
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int
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sys_vfork(struct lwp *l, void *v, register_t *retval)
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{
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return (fork1(l, FORK_PPWAIT, SIGCHLD, NULL, 0, NULL, NULL,
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retval, NULL));
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}
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/*
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* New vfork(2) system call for NetBSD, which implements original 3BSD vfork(2)
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* semantics. Address space is shared, and parent is blocked until child exit.
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*/
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/*ARGSUSED*/
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int
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sys___vfork14(struct lwp *l, void *v, register_t *retval)
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{
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return (fork1(l, FORK_PPWAIT|FORK_SHAREVM, SIGCHLD, NULL, 0,
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NULL, NULL, retval, NULL));
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}
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/*
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* Linux-compatible __clone(2) system call.
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*/
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int
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sys___clone(struct lwp *l, void *v, register_t *retval)
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{
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struct sys___clone_args /* {
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syscallarg(int) flags;
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syscallarg(void *) stack;
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} */ *uap = v;
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int flags, sig;
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/*
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* We don't support the CLONE_PID or CLONE_PTRACE flags.
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*/
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if (SCARG(uap, flags) & (CLONE_PID|CLONE_PTRACE))
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return (EINVAL);
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flags = 0;
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if (SCARG(uap, flags) & CLONE_VM)
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flags |= FORK_SHAREVM;
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if (SCARG(uap, flags) & CLONE_FS)
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flags |= FORK_SHARECWD;
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if (SCARG(uap, flags) & CLONE_FILES)
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flags |= FORK_SHAREFILES;
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if (SCARG(uap, flags) & CLONE_SIGHAND)
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flags |= FORK_SHARESIGS;
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if (SCARG(uap, flags) & CLONE_VFORK)
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flags |= FORK_PPWAIT;
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sig = SCARG(uap, flags) & CLONE_CSIGNAL;
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if (sig < 0 || sig >= _NSIG)
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return (EINVAL);
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/*
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* Note that the Linux API does not provide a portable way of
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* specifying the stack area; the caller must know if the stack
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* grows up or down. So, we pass a stack size of 0, so that the
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* code that makes this adjustment is a noop.
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*/
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return (fork1(l, flags, sig, SCARG(uap, stack), 0,
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NULL, NULL, retval, NULL));
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}
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/* print the 'table full' message once per 10 seconds */
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struct timeval fork_tfmrate = { 10, 0 };
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int
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fork1(struct lwp *l1, int flags, int exitsig, void *stack, size_t stacksize,
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void (*func)(void *), void *arg, register_t *retval,
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struct proc **rnewprocp)
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{
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struct proc *p1, *p2;
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uid_t uid;
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struct lwp *l2;
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int count, s;
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vaddr_t uaddr;
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boolean_t inmem;
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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 few processes; 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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p1 = l1->l_proc;
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uid = p1->p_cred->p_ruid;
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if (__predict_false((nprocs >= maxproc - 5 && uid != 0) ||
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nprocs >= maxproc)) {
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static struct timeval lasttfm;
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if (ratecheck(&lasttfm, &fork_tfmrate))
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tablefull("proc", "increase kern.maxproc or NPROC");
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if (forkfsleep)
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(void)tsleep(&nprocs, PUSER, "forkmx", forkfsleep);
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return (EAGAIN);
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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 (__predict_false(uid != 0 && count >
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p1->p_rlimit[RLIMIT_NPROC].rlim_cur)) {
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(void)chgproccnt(uid, -1);
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nprocs--;
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if (forkfsleep)
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(void)tsleep(&nprocs, PUSER, "forkulim", forkfsleep);
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return (EAGAIN);
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}
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/*
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* Allocate virtual address space for the U-area now, while it
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* is still easy to abort the fork operation if we're out of
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* kernel virtual address space. The actual U-area pages will
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* be allocated and wired in uvm_fork() if needed.
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*/
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inmem = uvm_uarea_alloc(&uaddr);
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if (__predict_false(uaddr == 0)) {
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(void)chgproccnt(uid, -1);
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nprocs--;
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return (ENOMEM);
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}
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/*
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* We are now committed to the fork. From here on, we may
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* block on resources, but resource allocation may NOT fail.
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*/
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/* Allocate new proc. */
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p2 = proc_alloc();
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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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memset(&p2->p_startzero, 0,
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(unsigned) ((caddr_t)&p2->p_endzero - (caddr_t)&p2->p_startzero));
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memcpy(&p2->p_startcopy, &p1->p_startcopy,
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(unsigned) ((caddr_t)&p2->p_endcopy - (caddr_t)&p2->p_startcopy));
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simple_lock_init(&p2->p_lwplock);
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LIST_INIT(&p2->p_lwps);
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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 uvm_fork().
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*/
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p2->p_flag = (p1->p_flag & P_SUGID);
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p2->p_emul = p1->p_emul;
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p2->p_execsw = p1->p_execsw;
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if (p1->p_flag & P_PROFIL)
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startprofclock(p2);
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p2->p_cred = pool_get(&pcred_pool, PR_WAITOK);
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memcpy(p2->p_cred, p1->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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LIST_INIT(&p2->p_raslist);
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p2->p_nras = 0;
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simple_lock_init(&p2->p_raslock);
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#if defined(__HAVE_RAS)
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ras_fork(p1, p2);
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#endif
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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 & FORK_SHAREFILES)
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fdshare(p1, p2);
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else if (flags & FORK_CLEANFILES)
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p2->p_fd = fdinit(p1);
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else
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p2->p_fd = fdcopy(p1);
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if (flags & FORK_SHARECWD)
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cwdshare(p1, p2);
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else
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p2->p_cwdi = cwdinit(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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/* Inherit STOPFORK and STOPEXEC flags */
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p2->p_flag |= p1->p_flag & (P_STOPFORK | P_STOPEXEC);
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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 & FORK_PPWAIT)
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p2->p_flag |= P_PPWAIT;
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p2->p_pptr = (flags & FORK_NOWAIT) ? initproc : p1;
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LIST_INIT(&p2->p_children);
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s = proclist_lock_write();
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LIST_INSERT_AFTER(p1, p2, p_pglist);
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LIST_INSERT_HEAD(&p2->p_pptr->p_children, p2, p_sibling);
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proclist_unlock_write(s);
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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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ktradref(p2);
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}
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#endif
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scheduler_fork_hook(p1, p2);
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/*
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* Create signal actions for the child process.
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*/
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sigactsinit(p2, p1, flags & FORK_SHARESIGS);
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/*
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* p_stats.
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* Copy parts of p_stats, and zero out the rest.
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*/
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p2->p_stats = pstatscopy(p1->p_stats);
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/*
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* If emulation has process fork hook, call it now.
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*/
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if (p2->p_emul->e_proc_fork)
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(*p2->p_emul->e_proc_fork)(p2, p1);
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/*
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* ...and finally, any other random fork hooks that subsystems
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* might have registered.
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*/
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doforkhooks(p2, p1);
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/*
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* This begins the section where we must prevent the parent
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* from being swapped.
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*/
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PHOLD(l1);
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uvm_proc_fork(p1, p2, (flags & FORK_SHAREVM) ? TRUE : FALSE);
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/*
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* Finish creating the child process.
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* It will return through a different path later.
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*/
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newlwp(l1, p2, uaddr, inmem, 0, stack, stacksize,
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(func != NULL) ? func : child_return,
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arg, &l2);
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/* Now safe for scheduler to see child process */
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s = proclist_lock_write();
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p2->p_stat = SIDL; /* protect against others */
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p2->p_exitsig = exitsig; /* signal for parent on exit */
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LIST_INSERT_HEAD(&allproc, p2, p_list);
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proclist_unlock_write(s);
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#ifdef SYSTRACE
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/* Tell systrace what's happening. */
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if (ISSET(p1->p_flag, P_SYSTRACE))
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systrace_sys_fork(p1, p2);
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#endif
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#ifdef __HAVE_SYSCALL_INTERN
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(*p2->p_emul->e_syscall_intern)(p2);
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#endif
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/*
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* Make child runnable, set start time, and add to run queue
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* except if the parent requested the child to start in SSTOP state.
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*/
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SCHED_LOCK(s);
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p2->p_stats->p_start = time;
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p2->p_acflag = AFORK;
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p2->p_nrlwps = 1;
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if (p1->p_flag & P_STOPFORK) {
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p2->p_stat = SSTOP;
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l2->l_stat = LSSTOP;
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} else {
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p2->p_stat = SACTIVE;
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l2->l_stat = LSRUN;
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setrunqueue(l2);
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}
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SCHED_UNLOCK(s);
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/*
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* Now can be swapped.
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*/
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PRELE(l1);
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/*
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* Notify any interested parties about the new process.
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*/
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KNOTE(&p1->p_klist, NOTE_FORK | p2->p_pid);
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/*
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* Update stats now that we know the fork was successful.
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*/
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uvmexp.forks++;
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if (flags & FORK_PPWAIT)
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uvmexp.forks_ppwait++;
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if (flags & FORK_SHAREVM)
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uvmexp.forks_sharevm++;
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/*
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* Pass a pointer to the new process to the caller.
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*/
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if (rnewprocp != NULL)
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*rnewprocp = p2;
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#ifdef KTRACE
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if (KTRPOINT(p2, KTR_EMUL))
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ktremul(p2);
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#endif
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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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if (flags & FORK_PPWAIT)
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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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if (retval != NULL) {
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retval[0] = p2->p_pid;
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retval[1] = 0;
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}
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return (0);
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}
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#if defined(MULTIPROCESSOR)
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/*
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* XXX This is a slight hack to get newly-formed processes to
|
|
* XXX acquire the kernel lock as soon as they run.
|
|
*/
|
|
void
|
|
proc_trampoline_mp(void)
|
|
{
|
|
struct lwp *l;
|
|
|
|
l = curlwp;
|
|
|
|
SCHED_ASSERT_UNLOCKED();
|
|
KERNEL_PROC_LOCK(l);
|
|
}
|
|
#endif
|