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NAME

kqueue_add_filteropts , kqueue_del_filteropts

 
kqfd_register

 
knote_fdclose

 
knlist_add , knlist_remove , knlist_remove_inevent , knlist_empty

 
knlist_init , knlist_destroy , knlist_clear , knlist_delete

 
KNOTE_LOCKED , KNOTE_UNLOCKED

 - event delivery subsystem

 

SYNOPSIS

DESCRIPTION

f_isfd

If f_isfd is set, ident in Vt struct kevent is taken to be a file descriptor. In this case, the Vt knote passed into f_attach will have the kn_fp member initialized to the Vt struct file * that represents the file descriptor.

f_attach

The f_attach function will be called when attaching a Vt knote to the object. The method should call knlist_add ();
to add the Vt knote to the list that was initialized with knlist_init (.);
The call to knlist_add ();
is only necessary if the object can have multiple Vt knotes associated with it. If there is no Vt knlist to call knlist_add ();
with, the function f_attach must clear the KN_DETACHED bit of kn_status in the Vt knote . The function shall return 0 on success, or appropriate error for the failure. During f_attach it is valid to change the kn_fops pointer to a different pointer. This will change the f_event and f_detach functions called when processing the Vt knote .

f_detach

The f_detach function will be called to detach the Vt knote if the Vt knote has not already been detached by a call to knlist_remove (.);

f_event

The 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 KNOTE_LOCKED or KNOTE_UNLOCKED The 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, knlist_remove_inevent ();
must be called. The function knlist_remove_inevent ();
will remove the note from the list, the f_detach function will not be called and the Vt knote will not be returned as an event.

Locks must not be acquired in f_event If a lock is required in f_event it must be obtained in the Fa kl_lock function of the Vt knlist that the knote was added to.

The function 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.

The function 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 kevent(2) call, so if userland uses the Vt knote to track resources, they will be leaked. The FILEDESC_LOCK ();
lock must be held over the call to knote_fdclose ();
so that file descriptors cannot be added or removed.

The 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 the knlist_init ();
function. If Fa lock is NULL an internal lock will be used and the remaining arguments will be ignored. The Fa kl_lock , kl_unlock and Fa kl_locked functions will be used to manipulate a Fa lock . If the argument is NULL default routines operating on Vt struct mtx * will be used. The Vt knlist structure may be embedded into the object structure. The Fa lock will be held over calls to f_event If NULL is passed for the mutex, a private mutex will be used. The function knlist_empty ();
requires that a Fa lock be held. The function knlist_clear ();
is used to remove all Vt knotes associated with the list. The Fa islocked argument declares if Fa lock has been acquired. All Vt knotes will be marked as detached, and EV_ONESHOT will be set so that the Vt knote will be deleted after the next scan. The knlist_destroy ();
function is used to destroy a Vt knlist . There must be no Vt knotes associated with the Vt knlist Fn ( knlist_empty returns true) and no more Vt knotes may be attached to the object. A Vt knlist may be emptied by calling knlist_clear (.);

The macros KNOTE_LOCKED ();
and 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 f_event function associated with the Vt knote . The macro KNOTE_LOCKED ();
must be used if the lock associated with the Fa knl passed in is held. The function KNOTE_UNLOCKED ();
will acquire the lock before iterating over the list of Vt knotes .  

RETURN VALUES

The function 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.

The function 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 kevent(2).  

SEE ALSO

AUTHORS

Index

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUES

SEE ALSO

AUTHORS

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