knote, KNOTE - raise kernel event
knote(struct klist *list, long hint);
KNOTE(struct klist *list, long hint);
The knote() function provides a hook into the kqueue kernel
mechanism to allow sections of the kernel to raise a
in the form of a `knote', which is a struct knote as defined
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
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
which may not be present in the data structure that the filter examines.
If the filter decides that the event should be returned, it
non-zero value and knote() links the knote onto the tail end
of the active
list in the corresponding kqueue for the application to
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
The knote() and KNOTE() functions first appeared in FreeBSD
4.1, and then
in OpenBSD 2.9.
The kqueue() system was written by Jonathan Lemon <jlemon@FreeBSD.org>.
OpenBSD 3.6 February 23, 2003
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