1.\" Copyright (c) 2015 Mark Johnston <markj@FreeBSD.org> 2.\" 3.\" Redistribution and use in source and binary forms, with or without 4.\" modification, are permitted provided that the following conditions 5.\" are met: 6.\" 1. Redistributions of source code must retain the above copyright 7.\" notice, this list of conditions and the following disclaimer. 8.\" 2. Redistributions in binary form must reproduce the above copyright 9.\" notice, this list of conditions and the following disclaimer in the 10.\" documentation and/or other materials provided with the distribution. 11.\" 12.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 13.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 14.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 15.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 16.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 17.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 18.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 19.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 20.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 21.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 22.\" 23.Dd November 7, 2015 24.Dt PHOLD 9 25.Os 26.Sh NAME 27.Nm PHOLD 28.Nd hold a process 29.Sh SYNOPSIS 30.In sys/proc.h 31.Fn PHOLD "struct proc *p" 32.Fn _PHOLD "struct proc *p" 33.Fn PRELE "struct proc *p" 34.Fn _PRELE "struct proc *p" 35.Fn PROC_ASSERT_HELD "struct proc *p" 36.Fn PROC_ASSERT_NOT_HELD "struct proc *p" 37.Sh DESCRIPTION 38The 39.Fn PHOLD 40macro increments the hold count of a process, and the 41.Fn PRELE 42macro decrements the hold count of a process. 43.Pp 44If a process with a non-zero hold count attempts to exit, it will sleep until 45its hold count has reached zero before the kernel begins releasing resources 46associated with the process. 47Once a process has started exiting, it is invalid to increase its hold count. 48Thus, callers must not attempt to hold a process that has the 49.Dv P_WEXIT 50flag set. 51The VM daemon will not swap out the kernel stack of a thread belonging to a 52process with a non-zero hold count. 53.Pp 54The 55.Fn _PHOLD 56and 57.Fn _PRELE 58macros are identical to 59.Fn PHOLD 60and 61.Fn PRELE , 62except that they must be called with the process lock held. 63.Sh AUTHORS 64This manual page was written by 65.An Mark Johnston Aq Mt markj@FreeBSD.org . 66