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 ALSO
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>.