'\" t
.\"     Title: threadgroup_lock
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: May 2018
.\"    Manual: Driver Basics
.\"    Source: Kernel Hackers Manual 3.16.56
.\"  Language: English
.\"
.TH "THREADGROUP_LOCK" "9" "May 2018" "Kernel Hackers Manual 3\&.16\&" "Driver Basics"
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.SH "NAME"
threadgroup_lock \- lock threadgroup
.SH "SYNOPSIS"
.HP \w'void\ threadgroup_lock('u
.BI "void threadgroup_lock(struct\ task_struct\ *\ " "tsk" ");"
.SH "ARGUMENTS"
.PP
\fItsk\fR
.RS 4
member task of the threadgroup to lock
.RE
.SH "DESCRIPTION"
.PP
Lock the threadgroup
\fItsk\fR
belongs to\&. No new task is allowed to enter and member tasks aren\*(Aqt allowed to exit (as indicated by PF_EXITING) or change \->group_leader/pid\&. This is useful for cases where the threadgroup needs to stay stable across blockable operations\&.
.PP
fork and exit paths explicitly call threadgroup_change_{begin|end}() for synchronization\&. While held, no new task will be added to threadgroup and no existing live task will have its PF_EXITING set\&.
.PP
\fBde_thread\fR
does threadgroup_change_{begin|end}() when a non\-leader sub\-thread becomes a new leader\&.
.SH "COPYRIGHT"
.br