'\" t
.\"     Title: wait_on_bit_lock
.\"    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 "WAIT_ON_BIT_LOCK" "9" "January 2017" "Kernel Hackers Manual 4\&.8\&." "Driver Basics"
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.SH "NAME"
wait_on_bit_lock \- wait for a bit to be cleared, when wanting to set it
.SH "SYNOPSIS"
.HP \w'int\ wait_on_bit_lock('u
.BI "int wait_on_bit_lock(unsigned\ long\ *\ " "word" ", int\ " "bit" ", unsigned\ " "mode" ");"
.SH "ARGUMENTS"
.PP
\fIword\fR
.RS 4
the word being waited on, a kernel virtual address
.RE
.PP
\fIbit\fR
.RS 4
the bit of the word being waited on
.RE
.PP
\fImode\fR
.RS 4
the task state to sleep in
.RE
.SH "DESCRIPTION"
.PP
There is a standard hashed waitqueue table for generic use\&. This is the part of the hashtable\*(Aqs accessor API that waits on a bit when one intends to set it, for instance, trying to lock bitflags\&. For instance, if one were to have waiters trying to set bitflag and waiting for it to clear before setting it, one would call
\fBwait_on_bit\fR
in threads waiting to be able to set the bit\&. One uses
\fBwait_on_bit_lock\fR
where one is waiting for the bit to clear with the intention of setting it, and when done, clearing it\&.
.PP
Returns zero if the bit was (eventually) found to be clear and was set\&. Returns non\-zero if a signal was delivered to the process and the
\fImode\fR
allows that signal to wake the process\&.
.SH "COPYRIGHT"
.br