117 lines
3.8 KiB
Groff
117 lines
3.8 KiB
Groff
.\" $NetBSD: knote.9,v 1.11 2004/02/18 16:50:25 jdolecek Exp $
|
|
.\"
|
|
.\" Copyright (c) 2001, 2002, 2003 The NetBSD Foundation, Inc.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" This documentation is derived from text contributed by
|
|
.\" Luke Mewburn.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed by the NetBSD
|
|
.\" Foundation, Inc. and its contributors.
|
|
.\" 4. Neither the name of The NetBSD Foundation nor the names of its
|
|
.\" contributors may be used to endorse or promote products derived
|
|
.\" from this software without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
|
|
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
|
|
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
|
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
|
|
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
|
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
|
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
|
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
|
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
.\" POSSIBILITY OF SUCH DAMAGE.
|
|
.\"
|
|
.Dd February 18, 2004
|
|
.Dt KNOTE 9
|
|
.Os
|
|
.Sh NAME
|
|
.Nm knote ,
|
|
.Nm KNOTE
|
|
.Nd raise kernel event
|
|
.Sh SYNOPSIS
|
|
.In sys/event.h
|
|
.Ft void
|
|
.Fn knote "struct klist *list" "long hint"
|
|
.Fn KNOTE "struct klist *list" "long hint"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn knote
|
|
function provides a hook into the kqueue kernel event notification
|
|
mechanism to allow sections of the kernel to raise a kernel event
|
|
in the form of a
|
|
.Sq knote ,
|
|
which is a
|
|
.Fa struct knote
|
|
as defined in
|
|
.Aq Pa sys/event.h .
|
|
.Pp
|
|
.Fn knote
|
|
takes a singly linked
|
|
.Fa list
|
|
of knotes, along with a
|
|
.Fa hint
|
|
(which is passed to the appropriate filter routine).
|
|
.Fn knote
|
|
then walks the
|
|
.Fa list
|
|
making calls to the filter routine for each knote.
|
|
As each knote contains a reference to the data structure that it is
|
|
attached to, the filter may choose to examine the data structure in
|
|
deciding whether an event should be reported.
|
|
The
|
|
.Fa hint
|
|
is used to pass in additional information, which may not be present in
|
|
the data structure that the filter examines.
|
|
.Pp
|
|
If the filter decides that the event should be returned, it returns a
|
|
non-zero value and
|
|
.Fn knote
|
|
links the knote onto the tail end of the active list in the
|
|
corresponding kqueue for the application to retrieve.
|
|
If the knote is already on the active list, no action is taken, but the
|
|
call to the filter occurs in order to provide an opportunity for the
|
|
filter to record the activity.
|
|
.Pp
|
|
.Fn knote
|
|
must not be called from interrupt contexts running at an interrupt
|
|
priority level higher than
|
|
.Fn splsched .
|
|
.Pp
|
|
.Fn KNOTE
|
|
is a macro that calls
|
|
.Fn knote list hint
|
|
if
|
|
.Fa list
|
|
is not empty.
|
|
.\" .Sh ERRORS
|
|
.Sh SEE ALSO
|
|
.Xr kqueue 2 ,
|
|
.Xr kfilter_register 9
|
|
.Sh HISTORY
|
|
The
|
|
.Fn knote
|
|
and
|
|
.Fn KNOTE
|
|
functions first appeared in
|
|
.Fx 4.1 ,
|
|
and then in
|
|
.Nx 2.0 .
|
|
.Sh AUTHORS
|
|
The
|
|
.Fn kqueue
|
|
system was written by
|
|
.An Jonathan Lemon Aq jlemon@FreeBSD.org .
|