113 lines
4.1 KiB
Groff
113 lines
4.1 KiB
Groff
.\" $NetBSD: kthread.9,v 1.1 2001/07/01 04:11:14 gmcgarry Exp $
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.\"
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.\" Copyright (c) 2000 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 Gregory McGarry.
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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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.Dd July 9, 2000
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.Dt KTHREAD 9
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.Os
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.Sh NAME
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.Nm kthread_create1 ,
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.Nm kthread_exit ,
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.Nm kthread_create
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.Nd kernel threads
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.Sh SYNOPSIS
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.Fd #include <sys/kthread.h>
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.Ft void
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.Fn kthread_create "void (*func)(void)" "void *arg"
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.Ft void
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.Fn kthread_exit "int ecode"
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.Ft int
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.Fn kthread_create1 "void (*func)(void)" "void *arg" "struct proc **newpp" \
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"const char *fmt" "..."
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.Sh DESCRIPTION
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Kernel threads are light-weight processes which execute entirely
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within the kernel. Any process can request the creation of a new
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kernel thread. Kernel threads are not swapped out during memory
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congestion. The VM space and limits are shaed with proc0 (usually
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.Xr init 8 ).
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.Sh FUNCTIONS
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.Bl -tag -width compact
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.It Fn kthread_create1 "func" "arg" "newpp" "fmt" "..."
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Fork a kernel thread.
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.Fa newpp
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is a pointer the the new proc structure for the kernel thread.
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The function
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.Fa func
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is called with arguments
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.Fa arg
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to commence execution.
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.Fa fmt
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is a string containing format information used to display the kernel
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thread name.
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.It Fn kthread_create "void (*func)(void)" "void *arg"
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Register function
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.Fa func
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to defer creation of the kernel thread. Deferral of kernel thread
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creation is required during system startup when kernel thread resources
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are not available.
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.It Fn kthread_exit "int ecode"
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Exit from a kernel thread.
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.El
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.Sh RETURN VALUES
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Upon successful completion,
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.Fn kthread_create1
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returns 0. Otherwise, the following error values are returned:
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.Bl -tag -width [EAGAIN]
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.It Bq Er EAGAIN
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The limit on the total number of system processes would be exceeded.
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.It Bq Er EAGAIN
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The limit
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.Dv RLIMIT_NPROC
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on the total number of processes under execution by this
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user id would be exceeded.
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.El
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.Sh CODE REFERENCES
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This section describes places within the
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.Nx
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source tree where actual code implementing or utilising the kthread
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framework can be found. All pathnames are relative to
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.Pa /usr/src.
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.Pp
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The kthread framework itself is implemented within the file
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.Pa sys/kern/kern_kthread.c .
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Data structures and function prototypes for the framework are located in
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.Pa sys/sys/kthread.h .
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.Sh SEE ALSO
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.Xr fork1 9 ,
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.Xr driver 9 .
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.Sh HISTORY
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The kthread framework appeared in
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.Nx 1.4 .
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