svcadm(8)을 검색하려면 섹션에서 8 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
EVENTHANDLER(9)
EVENTHANDLER(9) BSD Kernel Developer's Manual EVENTHANDLER(9)
NAME
EVENTHANDLER — kernel event handling functions
SYNOPSIS
#include <sys/eventhandler.h>
EVENTHANDLER_DECLARE(name, type);
EVENTHANDLER_DEFINE(name, func, arg, priority);
EVENTHANDLER_INVOKE(name, ...);
eventhandler_tag
EVENTHANDLER_REGISTER(name, func, arg, priority);
EVENTHANDLER_DEREGISTER(name, tag);
EVENTHANDLER_DEREGISTER_NOWAIT(name, tag);
EVENTHANDLER_LIST_DECLARE(name);
EVENTHANDLER_LIST_DEFINE(name);
EVENTHANDLER_DIRECT_INVOKE(name);
eventhandler_tag
eventhandler_register(struct eventhandler_list *list, const char *name,
void *func, void *arg, int priority);
void
eventhandler_deregister(struct eventhandler_list *list,
eventhandler_tag tag);
void
eventhandler_deregister_nowait(struct eventhandler_list *list,
eventhandler_tag tag);
struct eventhandler_list *
eventhandler_find_list(const char *name);
void
eventhandler_prune_list(struct eventhandler_list *list);
DESCRIPTION
The EVENTHANDLER mechanism provides a way for kernel subsystems to regis‐
ter interest in kernel events and have their callback functions invoked
when these events occur.
Callback functions are invoked in order of priority. The relative prior‐
ity of each callback among other callbacks associated with an event is
given by argument priority, which is an integer ranging from
EVENTHANDLER_PRI_FIRST (highest priority), to EVENTHANDLER_PRI_LAST (low‐
est priority). The symbol EVENTHANDLER_PRI_ANY may be used if the han‐
dler does not have a specific priority associated with it.
The normal way to use this subsystem is via the macro interface. For
events that are high frequency it is suggested that you additionally use
EVENTHANDLER_LIST_DEFINE() so that the event handlers can be invoked
directly using EVENTHANDLER_DIRECT_INVOKE() (see below). This saves the
invoker from having to do a locked traversal of a global list of event
handler lists.
EVENTHANDLER_DECLARE()
This macro declares an event handler named by argument name with
callback functions of type type.
EVENTHANDLER_DEFINE()
This macro uses SYSINIT(9) to register a callback function func
with event handler name. When invoked, function func will be
invoked with argument arg as its first parameter along with any
additional parameters passed in via macro EVENTHANDLER_INVOKE()
(see below).
EVENTHANDLER_REGISTER()
This macro registers a callback function func with event handler
name. When invoked, function func will be invoked with argument
arg as its first parameter along with any additional parameters
passed in via macro EVENTHANDLER_INVOKE() (see below). If regis‐
tration is successful, EVENTHANDLER_REGISTER() returns a cookie
of type eventhandler_tag.
EVENTHANDLER_DEREGISTER()
This macro removes a previously registered callback associated
with tag tag from the event handler named by argument name. It
waits until no threads are running handlers for this event before
returning, making it safe to unload a module immediately upon
return from this function.
EVENTHANDLER_DEREGISTER_NOWAIT()
This macro removes a previously registered callback associated
with tag tag from the event handler named by argument name. Upon
return, one or more threads could still be running the removed
function(s), but no new calls will be made. To remove a handler
function from within that function, use this version of deregis‐
ter, to avoid a deadlock.
EVENTHANDLER_INVOKE()
This macro is used to invoke all the callbacks associated with
event handler name. This macro is a variadic one. Additional
arguments to the macro after the name parameter are passed as the
second and subsequent arguments to each registered callback func‐
tion.
EVENTHANDLER_LIST_DEFINE()
This macro defines a reference to an event handler list named by
argument name. It uses SYSINIT(9) to initialize the reference
and the eventhandler list.
EVENTHANDLER_LIST_DECLARE()
This macro declares an event handler list named by argument name.
This is only needed for users of EVENTHANDLER_DIRECT_INVOKE()
which are not in the same compilation unit of that list's defini‐
tion.
EVENTHANDLER_DIRECT_INVOKE()
This macro invokes the event handlers registered for the list
named by argument name. This macro can only be used if the list
was defined with EVENTHANDLER_LIST_DEFINE(). The macro is vari‐
adic with the same semantics as EVENTHANDLER_INVOKE().
The macros are implemented using the following functions:
eventhandler_register()
The eventhandler_register() function is used to register a call‐
back with a given event. The arguments expected by this function
are:
list A pointer to an existing event handler list, or NULL.
If list is NULL, the event handler list corresponding
to argument name is used.
name The name of the event handler list.
func A pointer to a callback function. Argument arg is
passed to the callback function func as its first argu‐
ment when it is invoked.
priority The relative priority of this callback among all the
callbacks registered for this event. Valid values are
those in the range EVENTHANDLER_PRI_FIRST to
EVENTHANDLER_PRI_LAST.
The eventhandler_register() function returns a tag that can later
be used with eventhandler_deregister() to remove the particular
callback function.
eventhandler_deregister()
The eventhandler_deregister() function removes the callback asso‐
ciated with tag tag from the event handler list pointed to by
list. If tag is NULL, all callback functions for the event are
removed. This function will not return until all threads have
exited from the removed handler callback function(s). This func‐
tion is not safe to call from inside an event handler callback.
eventhandler_deregister_nowait()
The eventhandler_deregister() function removes the callback asso‐
ciated with tag tag from the event handler list pointed to by
list. This function is safe to call from inside an event handler
callback.
eventhandler_find_list()
The eventhandler_find_list() function returns a pointer to event
handler list structure corresponding to event name.
eventhandler_prune_list()
The eventhandler_prune_list() function removes all deregistered
callbacks from the event list list.
Kernel Event Handlers
The following event handlers are present in the kernel:
acpi_sleep_event
Callbacks invoked when the system is being sent to sleep.
acpi_wakeup_event
Callbacks invoked when the system is being woken up.
app_coredump_start
Callbacks invoked at start of application core dump.
app_coredump_progress
Callbacks invoked during progress of application core dump.
app_coredump_finish
Callbacks invoked at finish of application core dump.
app_coredump_error
Callbacks invoked on error of application core dump.
bpf_track
Callbacks invoked when a BPF listener attaches to/detaches from
network interface.
cpufreq_levels_changed
Callback invoked when cpu frequency levels have changed.
cpufreq_post_change
Callback invoked after cpu frequency has changed.
cpufreq_pre_change
Callback invoked before cpu frequency has changed.
dcons_poll
Callback invoked to poll for dcons changes.
device_attach
Callback invoked after a device has attached.
device_detach
Callbacks invoked before and after a device has detached.
dev_clone
Callbacks invoked when a new entry is created under /dev.
group_attach_event
Callback invoked when an interfance has been added to an inter‐
face group.
group_change_event
Callback invoked when an change has been made to an interface
group.
group_detach_event
Callback invoked when an interfance has been removed from an
interface group.
ifaddr_event
Callbacks invoked when an address is set up on a network inter‐
face.
if_clone_event
Callbacks invoked when an interface is cloned.
iflladdr_event
Callback invoked when an if link layer address event has hap‐
pened.
ifnet_arrival_event
Callbacks invoked when a new network interface appears.
ifnet_departure_event
Callbacks invoked when a network interface is taken down.
ifnet_link_event
Callback invoked when an interfance link event has happened.
kld_load
Callbacks invoked after a linker file has been loaded.
kld_unload
Callbacks invoked after a linker file has been successfully
unloaded.
kld_unload_try
Callbacks invoked before a linker file is about to be unloaded.
These callbacks may be used to return an error and prevent the
unload from proceeding.
lle_event
Callback invoked when an link layer event has happened.
nmbclusters_change
Callback invoked when the number of mbuf clusters has changed.
nmbufs_change
Callback invoked when the number of mbufs has changed.
maxsockets_change
Callback invoked when the maximum number of sockets has changed.
mountroot
Callback invoked when root has been mounted.
power_profile_change
Callbacks invoked when the power profile of the system changes.
power_resume
Callback invoked when the system has resumed.
power_suspend
Callback invoked just before the system is suspended.
process_ctor
Callback invoked when a process is created.
process_dtor
Callback invoked when a process is destroyed.
process_exec
Callbacks invoked when a process performs an exec() operation.
process_exit
Callbacks invoked when a process exits.
process_fini
Callback invoked when a process memory is destroyed. This is
never called.
process_fork
Callbacks invoked when a process forks a child.
process_init
Callback invoked when a process is initialized.
random_adaptor_attach
Callback invoked when a new random module has been loaded.
register_framebuffer
Callback invoked when a new frame buffer is registered.
route_redirect_event
Callback invoked when a route gets redirected to a new location.
shutdown_pre_sync
Callbacks invoked at shutdown time, before file systems are syn‐
chronized.
shutdown_post_sync
Callbacks invoked at shutdown time, after all file systems are
synchronized.
shutdown_final
Callbacks invoked just before halting the system.
tcp_offload_listen_start
Callback invoked for TCP Offload to start listening for new con‐
nections.
tcp_offload_listen_stop
Callback invoked ror TCP Offload to stop listening for new con‐
nections.
thread_ctor
Callback invoked when a thread object is created.
thread_dtor
Callback invoked when a thread object is destroyed.
thread_init
Callback invoked when a thread object is initialized.
thread_fini
Callback invoked when a thread object is deinitalized.
usb_dev_configured
Callback invoked when a USB device is configured
unregister_framebuffer
Callback invoked when a frame buffer is deregistered.
vfs_mounted
Callback invoked when a file system is mounted.
vfs_unmounted
Callback invoked when a file system is unmounted.
vlan_config
Callback invoked when the vlan configuration has changed.
vlan_unconfig
Callback invoked when a vlan is destroyed.
vm_lowmem
Callbacks invoked when virtual memory is low.
watchdog_list
Callbacks invoked when the system watchdog timer is reinitial‐
ized.
RETURN VALUES
The macro EVENTHANDLER_REGISTER() and function eventhandler_register()
return a cookie of type eventhandler_tag, which may be used in a subse‐
quent call to EVENTHANDLER_DEREGISTER() or eventhandler_deregister().
The eventhandler_find_list() function returns a pointer to an event han‐
dler list corresponding to parameter name, or NULL if no such list was
found.
HISTORY
The EVENTHANDLER facility first appeared in FreeBSD 4.0.
AUTHORS
This manual page was written by Joseph Koshy <jkoshy@FreeBSD.org> and
Matt Joras <mjoras@FreeBSD.org>.
BSD September 6, 2018 BSD