diff --git a/share/man/man9/kqueue.9 b/share/man/man9/kqueue.9
index ee56358b9e86..53f55b8efe03 100644
--- a/share/man/man9/kqueue.9
+++ b/share/man/man9/kqueue.9
@@ -1,467 +1,467 @@
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 .\"
 .\" Redistribution and use in source and binary forms, with or without
 .\" modification, are permitted provided that the following conditions
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 .\" 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.
 .\"
 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR OR CONTRIBUTORS BE LIABLE
 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 .\" 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.
 .\"
 .\" $FreeBSD$
 .\"
-.Dd March 26, 2012
+.Dd October 12, 2021
 .Dt KQUEUE 9
 .Os
 .Sh NAME
 .Nm kqueue_add_filteropts , kqueue_del_filteropts ,
 .Nm kqfd_register ,
 .Nm knote_fdclose ,
 .Nm knlist_init , knlist_init_mtx , knlist_init_rw_reader ,
 .Nm knlist_add , knlist_remove , knlist_remove_inevent , knlist_empty ,
 .Nm knlist_clear , knlist_delete , knlist_destroy ,
 .Nm KNOTE_LOCKED , KNOTE_UNLOCKED
 .Nd "event delivery subsystem"
 .Sh SYNOPSIS
 .In sys/event.h
 .Ft int
 .Fn kqueue_add_filteropts "int filt" "struct filterops *filtops"
 .Ft int
 .Fn kqueue_del_filteropts "int filt"
 .Ft int
 .Fn kqfd_register "int fd" "struct kevent *kev" "struct thread *td" "int waitok"
 .Ft void
 .Fn knote_fdclose "struct thread *td" "int fd"
 .Ft void
 .Fo knlist_init
 .Fa "struct knlist *knl"
 .Fa "void *lock"
 .Fa "void \*[lp]*kl_lock\*[rp]\*[lp]void *\*[rp]"
 .Fa "void \*[lp]*kl_unlock\*[rp]\*[lp]void *\*[rp]"
 .Fa "int \*[lp]*kl_locked\*[rp]\*[lp]void *\*[rp]"
 .Fc
 .Ft void
 .Fn knlist_init_mtx "struct knlist *knl" "struct mtx *lock"
 .Ft void
 .Fn knlist_init_rw_reader "struct knlist *knl" "struct rwlock *lock"
 .Ft void
 .Fn knlist_add "struct knlist *knl" "struct knote *kn" "int islocked"
 .Ft void
 .Fn knlist_remove "struct knlist *knl" "struct knote *kn" "int islocked"
 .Ft void
 .Fn knlist_remove_inevent "struct knlist *knl" "struct knote *kn"
 .Ft int
 .Fn knlist_empty "struct knlist *knl"
 .Ft void
 .Fn knlist_clear "struct knlist *knl" "int islocked"
 .Ft void
 .Fn knlist_delete "struct knlist *knl" "struct thread *td" "int islocked"
 .Ft void
 .Fn knlist_destroy "struct knlist *knl"
 .Ft void
 .Fn KNOTE_LOCKED "struct knlist *knl" "long hint"
 .Ft void
 .Fn KNOTE_UNLOCKED "struct knlist *knl" "long hint"
 .Sh DESCRIPTION
 The functions
 .Fn kqueue_add_filteropts
 and
 .Fn kqueue_del_filteropts
 allow for the addition and removal of a filter type.
 The filter is statically defined by the
 .Dv EVFILT_*
 macros.
 The function
 .Fn kqueue_add_filteropts
 will make
 .Fa filt
 available.
 The
 .Vt "struct filterops"
 has the following members:
 .Bl -tag -width ".Va f_attach"
 .It Va f_isfd
 If
 .Va f_isfd
 is set,
 .Va ident
 in
 .Vt "struct kevent"
 is taken to be a file descriptor.
 In this case, the
 .Vt knote
 passed into
 .Va f_attach
 will have the
 .Va kn_fp
 member initialized to the
 .Vt "struct file *"
 that represents the file descriptor.
 .It Va f_attach
 The
 .Va f_attach
 function will be called when attaching a
 .Vt knote
 to the object.
 The method should call
 .Fn knlist_add
 to add the
 .Vt knote
 to the list that was initialized with
 .Fn knlist_init .
 The call to
 .Fn knlist_add
 is only necessary if the object can have multiple
 .Vt knotes
 associated with it.
 If there is no
 .Vt knlist
 to call
 .Fn knlist_add
 with, the function
 .Va f_attach
 must clear the
 .Dv KN_DETACHED
 bit of
 .Va kn_status
 in the
 .Vt knote .
 The function shall return 0 on success, or appropriate error for the failure,
 such as when the object is being destroyed, or does not exist.
 During
 .Va f_attach ,
 it is valid to change the
-.Va kn_fops
+.Va kn_fop
 pointer to a different pointer.
 This will change the
 .Va f_event
 and
 .Va f_detach
 functions called when processing the
 .Vt knote .
 .It Va f_detach
 The
 .Va f_detach
 function will be called to detach the
 .Vt knote
 if the
 .Vt knote
 has not already been detached by a call to
 .Fn knlist_remove ,
 .Fn knlist_remove_inevent
 or
 .Fn knlist_delete .
 The list
 .Fa lock
 will not be held when this function is called.
 .It Va f_event
 The
 .Va f_event
 function will be called to update the status of the
 .Vt knote .
 If the function returns 0, it will be assumed that the object is not
 ready (or no longer ready) to be woken up.
 The
 .Fa hint
 argument will be 0 when scanning
 .Vt knotes
 to see which are triggered.
 Otherwise, the
 .Fa hint
 argument will be the value passed to either
 .Dv KNOTE_LOCKED
 or
 .Dv KNOTE_UNLOCKED .
 The
 .Va kn_data
 value should be updated as necessary to reflect the current value, such as
 number of bytes available for reading, or buffer space available for writing.
 If the note needs to be removed,
 .Fn knlist_remove_inevent
 must be called.
 The function
 .Fn knlist_remove_inevent
 will remove the note from the list, the
 .Va f_detach
 function will not be called and the
 .Vt knote
 will not be returned as an event.
 .Pp
 Locks
 .Em must not
 be acquired in
 .Va f_event .
 If a lock is required in
 .Va f_event ,
 it must be obtained in the
 .Fa kl_lock
 function of the
 .Vt knlist
 that the
 .Va knote
 was added to.
 .El
 .Pp
 The function
 .Fn kqfd_register
 will register the
 .Vt kevent
 on the kqueue file descriptor
 .Fa fd .
 If it is safe to sleep,
 .Fa waitok
 should be set.
 .Pp
 The function
 .Fn knote_fdclose
 is used to delete all
 .Vt knotes
 associated with
 .Fa fd .
 Once returned, there will no longer be any
 .Vt knotes
 associated with the
 .Fa fd .
 The
 .Vt knotes
 removed will never be returned from a
 .Xr kevent 2
 call, so if userland uses the
 .Vt knote
 to track resources, they will be leaked.
 The
 .Fn FILEDESC_LOCK
 lock must be held over the call to
 .Fn knote_fdclose
 so that file descriptors cannot be added or removed.
 .Pp
 The
 .Fn knlist_*
 family of functions are for managing
 .Vt knotes
 associated with an object.
 A
 .Vt knlist
 is not required, but is commonly used.
 If used, the
 .Vt knlist
 must be initialized with either
 .Fn knlist_init ,
 .Fn knlist_init_mtx
 or
 .Fn knlist_init_rw_reader .
 The
 .Vt knlist
 structure may be embedded into the object structure.
 The
 .Fa lock
 will be held over
 .Va f_event
 calls.
 .Pp
 For the
 .Fn knlist_init
 function, if
 .Fa lock
 is
 .Dv NULL ,
 a shared global lock will be used and the remaining arguments must be
 .Dv NULL .
 The function pointers
 .Fa kl_lock , kl_unlock
 and
 .Fa kl_locked
 will be used to manipulate the argument
 .Fa lock .
 If any of the function pointers are
 .Dv NULL ,
 a function operating on
 .Dv MTX_DEF
 style
 .Xr mutex 9
 locks will be used instead.
 .Pp
 The function
 .Fn knlist_init_mtx
 may be used to initialize a
 .Vt knlist
 when
 .Fa lock
 is a
 .Dv MTX_DEF
 style
 .Xr mutex 9
 lock.
 .Pp
 The function
 .Fn knlist_init_rw_reader
 may be used to initialize a
 .Vt knlist
 when
 .Fa lock
 is a
 .Xr rwlock 9
 read lock.
 Lock is acquired via
 .Fn rw_rlock
 function.
 .Pp
 The function
 .Fn knlist_empty
 returns true when there are no
 .Vt knotes
 on the list.
 The function requires that the
 .Fa lock
 be held when called.
 .Pp
 The function
 .Fn knlist_clear
 removes all
 .Vt knotes
 from the list.
 The
 .Fa islocked
 argument declares if the
 .Fa lock
 has been acquired.
 All
 .Vt knotes
 will have
 .Dv EV_ONESHOT
 set so that the
 .Vt knote
 will be returned and removed during the next scan.
 The
 .Va f_detach
 function will be called when the
 .Vt knote
 is deleted during the next scan.
 This function must not be used when
 .Va f_isfd
 is set in
 .Vt "struct filterops" ,
 as the
 .Fa td
 argument of
 .Fn fdrop
 will be
 .Dv NULL .
 .Pp
 The function
 .Fn knlist_delete
 removes and deletes all
 .Vt knotes
 on the list.
 The function
 .Va f_detach
 will not be called, and the
 .Vt knote
 will not be returned on the next scan.
 Using this function could leak userland resources if a process uses the
 .Vt knote
 to track resources.
 .Pp
 Both the
 .Fn knlist_clear
 and
 .Fn knlist_delete
 functions may sleep.
 They also may release the
 .Fa lock
 to wait for other
 .Vt knotes
 to drain.
 .Pp
 The
 .Fn knlist_destroy
 function is used to destroy a
 .Vt knlist .
 There must be no
 .Vt knotes
 associated with the
 .Vt knlist
 .Po Fn knlist_empty
 returns true
 .Pc
 and no more
 .Vt knotes
 may be attached to the object.
 A
 .Vt knlist
 may be emptied by calling
 .Fn knlist_clear
 or
 .Fn knlist_delete .
 .Pp
 The macros
 .Fn KNOTE_LOCKED
 and
 .Fn KNOTE_UNLOCKED
 are used to notify
 .Vt knotes
 about events associated with the object.
 It will iterate over all
 .Vt knotes
 on the list calling the
 .Va f_event
 function associated with the
 .Vt knote .
 The macro
 .Fn KNOTE_LOCKED
 must be used if the lock associated with the
 .Fa knl
 is held.
 The function
 .Fn KNOTE_UNLOCKED
 will acquire the lock before iterating over the list of
 .Vt knotes .
 .Sh RETURN VALUES
 The function
 .Fn kqueue_add_filteropts
 will return zero on success,
 .Er EINVAL
 in the case of an invalid
 .Fa filt ,
 or
 .Er EEXIST
 if the filter has already been installed.
 .Pp
 The function
 .Fn kqueue_del_filteropts
 will return zero on success,
 .Er EINVAL
 in the case of an invalid
 .Fa filt ,
 or
 .Er EBUSY
 if the filter is still in use.
 .Pp
 The function
 .Fn kqfd_register
 will return zero on success,
 .Er EBADF
 if the file descriptor is not a kqueue, or any of the possible values returned
 by
 .Xr kevent 2 .
 .Sh SEE ALSO
 .Xr kevent 2 ,
 .Xr kqueue 2
 .Sh AUTHORS
 This
 manual page was written by
 .An John-Mark Gurney Aq Mt jmg@FreeBSD.org .