'\" t
.\"     Title: rcu_read_lock_bh_held
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: January 2017
.\"    Manual: Driver Basics
.\"    Source: Kernel Hackers Manual 4.8.15
.\"  Language: English
.\"
.TH "RCU_READ_LOCK_BH_HEL" "9" "January 2017" "Kernel Hackers Manual 4\&.8\&." "Driver Basics"
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.SH "NAME"
rcu_read_lock_bh_held \- might we be in RCU\-bh read\-side critical section?
.SH "SYNOPSIS"
.HP \w'int\ rcu_read_lock_bh_held('u
.BI "int rcu_read_lock_bh_held(" "void" ");"
.SH "ARGUMENTS"
.PP
\fIvoid\fR
.RS 4
no arguments
.RE
.SH "DESCRIPTION"
.PP
.PP
Check for bottom half being disabled, which covers both the CONFIG_PROVE_RCU and not cases\&. Note that if someone uses
\fBrcu_read_lock_bh\fR, but then later enables BH, lockdep (if enabled) will show the situation\&. This is useful for debug checks in functions that require that they be called within an RCU read\-side critical section\&.
.PP
Check
\fBdebug_lockdep_rcu_enabled\fR
to prevent false positives during boot\&.
.PP
Note that
\fBrcu_read_lock\fR
is disallowed if the CPU is either idle or offline from an RCU perspective, so check for those as well\&.
.SH "COPYRIGHT"
.br