KNOTE(9) OpenBSD Kernel Manual KNOTE(9)NAME
knote, KNOTE - raise kernel event
SYNOPSIS
#include <sys/param.h>
#include <sys/event.h>
void
knote(struct klist *list, long hint);
KNOTE(struct klist *list, long hint);
DESCRIPTION
The 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 `knote', which is a struct knote as defined in
<sys/event.h>.
knote() takes a singly linked list of knotes, along with a hint (which is
passed to the appropriate filter routine). knote() then walks the 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 hint is used to pass in additional
information, which may not be present in the data structure that the
filter examines.
If the filter decides that the event should be returned, it returns a
non-zero value and 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.
knote() must not be called from interrupt contexts running at an
interrupt priority level higher than splsched().
KNOTE() is a macro that calls knote(list, hint) if list is not empty.
SEE ALSOkqueue(2)HISTORY
The knote() and KNOTE() functions first appeared in FreeBSD 4.1, and then
in OpenBSD 2.9.
AUTHORS
The kqueue() system was written by Jonathan Lemon <jlemon@FreeBSD.org>.
OpenBSD 4.9 June 26, 2008 OpenBSD 4.9
