NAME    [Toc]    [Back]

     knote, KNOTE - raise kernel event

SYNOPSIS    [Toc]    [Back]

     #include <sys/param.h>
     #include <sys/event.h>

     void
     knote(struct klist *list, long hint);

     KNOTE(struct klist *list, long hint);

DESCRIPTION    [Toc]    [Back]

     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    [Toc]    [Back]

     kqueue(2)

HISTORY    [Toc]    [Back]

     The  knote() and KNOTE() functions first appeared in FreeBSD
4.1, and then
     in OpenBSD 2.9.

AUTHORS    [Toc]    [Back]

     The kqueue() system was  written  by  Jonathan  Lemon  <jle[email protected]>.

OpenBSD      3.6                        February     23,     2003