68 lines
2.4 KiB
Groff
68 lines
2.4 KiB
Groff
.\" Copyright (c) 2015 Mark Johnston <markj@FreeBSD.org>
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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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd November 7, 2015
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.Dt PHOLD 9
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.Os
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.Sh NAME
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.Nm PHOLD
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.Nd hold a process
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.Sh SYNOPSIS
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.In sys/proc.h
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.Fn PHOLD "struct proc *p"
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.Fn _PHOLD "struct proc *p"
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.Fn PRELE "struct proc *p"
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.Fn _PRELE "struct proc *p"
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.Fn PROC_ASSERT_HELD "struct proc *p"
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.Fn PROC_ASSERT_NOT_HELD "struct proc *p"
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.Sh DESCRIPTION
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The
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.Fn PHOLD
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macro increments the hold count of a process, and the
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.Fn PRELE
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macro decrements the hold count of a process.
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.Pp
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If a process with a non-zero hold count attempts to exit, it will sleep until
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its hold count has reached zero before the kernel begins releasing resources
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associated with the process.
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Once a process has started exiting, it is invalid to increase its hold count.
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Thus, callers must not attempt to hold a process that has the
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.Dv P_WEXIT
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flag set.
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The VM daemon will not swap out the kernel stack of a thread belonging to a
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process with a non-zero hold count.
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.Pp
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The
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.Fn _PHOLD
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and
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.Fn _PRELE
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macros are identical to
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.Fn PHOLD
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and
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.Fn PRELE ,
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except that they must be called with the process lock held.
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.Sh AUTHORS
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This manual page was written by
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.An Mark Johnston Aq Mt markj@FreeBSD.org .
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