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.\" -*- nroff -*-
.\"
.\" copyright (C) 1997 Stephen Williams <steve@icarus.com>
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein. The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.TH poll_wait 9 "$Date:$" "Linux DDI" "Kernel Functions"
.\"
.\" Turn off hyphenation and right justification for the first sections.
.hlm 0
.na
.\" The name should be formatted this way for apropos to work
.SH NAME
poll_wait \- wait for selectable event to be ready
.\"
.\"
.SH SYNOPSIS
.B #include <linux/poll.h>
.PP
.BI "void poll_wait(struct\%wait_queue**" sync ", poll_table*" pt ")"
.HP
.\"
.\" Turn hyphenation and adjustment back on.
.hlm 1
.ad
.SH DESCRIPTION
This function is used in support of the poll device driver entry
point. The intent is for a device driver to put
.I sync
into the poll table immediately entering the device poll routine, then
returning a bit mask of events that are currently ready. The kernel
looks at the mask of events to see if something it needs is ready, and
suspends the process if not.
.PP
.nf
static unsigned int xxpoll(struct file*file, poll_table*pt)
{
poll_wait(&data_in_sync, pt);
if (data_in.cnt > 0) return POLLIN | POLLRDNORM;
else return 0;
}
.fi
.PP
This example shows the basic use of
.BR poll_wait "(9)"
in a device driver poll function.
.SH AVAILABILITY
Linux kernel 2.1.34+
.SH "SEE ALSO"
.hlm 0
.na
.BR intro "(9)"
.ad
.hlm 1
.SH AUTHOR
Stephen Williams <steve@icarus.com>
.SH BUGS
To early to say.
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