From 635458bc065a0c33e8d8fe87cc2506219aadca11 Mon Sep 17 00:00:00 2001 From: Mark Johnston Date: Sun, 8 Nov 2015 01:41:44 +0000 Subject: [PATCH] Add a manual page for PHOLD() and friends. MFC after: 1 week --- share/man/man9/Makefile | 6 ++++ share/man/man9/PHOLD.9 | 67 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 73 insertions(+) create mode 100644 share/man/man9/PHOLD.9 diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile index f5f51640225b..530dff31c8dd 100644 --- a/share/man/man9/Makefile +++ b/share/man/man9/Makefile @@ -209,6 +209,7 @@ MAN= accept_filter.9 \ pfind.9 \ pget.9 \ pgfind.9 \ + PHOLD.9 \ physio.9 \ pmap.9 \ pmap_activate.9 \ @@ -1314,6 +1315,11 @@ MLINKS+=pfil.9 pfil_add_hook.9 \ pfil.9 pfil_wlock.9 \ pfil.9 pfil_wunlock.9 MLINKS+=pfind.9 zpfind.9 +MLINKS+=PHOLD.9 PRELE.9 \ + PHOLD.9 _PHOLD.9 \ + PHOLD.9 _PRELE.9 \ + PHOLD.9 PROC_ASSERT_HELD.9 \ + PHOLD.9 PROC_ASSERT_NOT_HELD.9 MLINKS+=pmap_copy.9 pmap_copy_page.9 MLINKS+=pmap_extract.9 pmap_extract_and_hold.9 MLINKS+=pmap_init.9 pmap_init2.9 diff --git a/share/man/man9/PHOLD.9 b/share/man/man9/PHOLD.9 new file mode 100644 index 000000000000..12e0f3e02f99 --- /dev/null +++ b/share/man/man9/PHOLD.9 @@ -0,0 +1,67 @@ +.\" Copyright (c) 2015 Mark Johnston +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR +.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES +.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. +.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, +.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT +.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF +.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +.\" +.\" $FreeBSD$ +.\" +.Dd November 7, 2015 +.Dt PHOLD 9 +.Os +.Sh NAME +.Nm PHOLD +.Nd hold a process +.Sh SYNOPSIS +.In sys/proc.h +.Fn PHOLD "struct proc *p" +.Fn _PHOLD "struct proc *p" +.Fn PRELE "struct proc *p" +.Fn _PRELE "struct proc *p" +.Fn PROC_ASSERT_HELD "struct proc *p" +.Fn PROC_ASSERT_NOT_HELD "struct proc *p" +.Sh DESCRIPTION +The +.Fn PHOLD +macro increments the hold count of a process, and the +.Fn PRELE +macro decrements the hold count of a process. +.Pp +If a process with a non-zero hold count attempts to exit, it will sleep until +its hold count has reached zero before the kernel begins releasing resources +associated with the process. +Once a process has started exiting, it is invalid to increase its hold count. +Thus, callers must not attempt to hold a process that has the +.Dv P_WEXIT +flag set. +The VM daemon will not swap out the kernel stack of a thread belonging to a +process with a non-zero hold count. +.Pp +The +.Fn _PHOLD +and +.Fn _PRELE +macros are identical to +.Fn PHOLD +and +.Fn PRELE , +except that they must be called with the process lock held. +.Sh AUTHORS +This manual page was written by +.An Mark Johnston Aq Mt markj@FreeBSD.org .