Index: head/share/man/man9/EVENTHANDLER.9 =================================================================== --- head/share/man/man9/EVENTHANDLER.9 (revision 338503) +++ head/share/man/man9/EVENTHANDLER.9 (revision 338504) @@ -1,418 +1,422 @@ .\" Copyright (c) 2004 Joseph Koshy .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 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 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" 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 October 31, 2017 +.Dd September 6, 2018 .Dt EVENTHANDLER 9 .Os .Sh NAME .Nm EVENTHANDLER .Nd kernel event handling functions .Sh SYNOPSIS .In sys/eventhandler.h .Fn EVENTHANDLER_DECLARE name type .Fn EVENTHANDLER_DEFINE name func arg priority .Fn EVENTHANDLER_INVOKE name ... .Ft eventhandler_tag .Fn EVENTHANDLER_REGISTER name func arg priority .Fn EVENTHANDLER_DEREGISTER name tag .Fn EVENTHANDLER_DEREGISTER_NOWAIT name tag .Fn EVENTHANDLER_LIST_DECLARE name .Fn EVENTHANDLER_LIST_DEFINE name .Fn EVENTHANDLER_DIRECT_INVOKE name .Ft eventhandler_tag .Fo eventhandler_register .Fa "struct eventhandler_list *list" .Fa "const char *name" .Fa "void *func" .Fa "void *arg" .Fa "int priority" .Fc .Ft void .Fo eventhandler_deregister .Fa "struct eventhandler_list *list" .Fa "eventhandler_tag tag" .Fc .Ft void .Fo eventhandler_deregister_nowait .Fa "struct eventhandler_list *list" .Fa "eventhandler_tag tag" .Fc .Ft "struct eventhandler_list *" .Fn eventhandler_find_list "const char *name" .Ft void .Fn eventhandler_prune_list "struct eventhandler_list *list" .Sh DESCRIPTION The .Nm mechanism provides a way for kernel subsystems to register interest in kernel events and have their callback functions invoked when these events occur. .Pp Callback functions are invoked in order of priority. The relative priority of each callback among other callbacks associated with an event is given by argument .Fa priority , which is an integer ranging from .Dv EVENTHANDLER_PRI_FIRST (highest priority), to .Dv EVENTHANDLER_PRI_LAST (lowest priority). The symbol .Dv EVENTHANDLER_PRI_ANY may be used if the handler does not have a specific priority associated with it. .Pp 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 .Fn EVENTHANDLER_LIST_DEFINE so that the event handlers can be invoked directly using .Fn EVENTHANDLER_DIRECT_INVOKE (see below). This saves the invoker from having to do a locked traversal of a global list of event handler lists. .Bl -tag -width indent .It Fn EVENTHANDLER_DECLARE This macro declares an event handler named by argument .Fa name with callback functions of type .Fa type . .It Fn EVENTHANDLER_DEFINE This macro uses .Xr SYSINIT 9 to register a callback function .Fa func with event handler .Fa name . When invoked, function .Fa func will be invoked with argument .Fa arg as its first parameter along with any additional parameters passed in via macro .Fn EVENTHANDLER_INVOKE (see below). .It Fn EVENTHANDLER_REGISTER This macro registers a callback function .Fa func with event handler .Fa name . When invoked, function .Fa func will be invoked with argument .Fa arg as its first parameter along with any additional parameters passed in via macro .Fn EVENTHANDLER_INVOKE (see below). If registration is successful, .Fn EVENTHANDLER_REGISTER returns a cookie of type .Vt eventhandler_tag . .It Fn EVENTHANDLER_DEREGISTER This macro removes a previously registered callback associated with tag .Fa tag from the event handler named by argument .Fa 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. .It Fn EVENTHANDLER_DEREGISTER_NOWAIT This macro removes a previously registered callback associated with tag .Fa tag from the event handler named by argument .Fa 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 deregister, to avoid a deadlock. .It Fn EVENTHANDLER_INVOKE This macro is used to invoke all the callbacks associated with event handler .Fa name . This macro is a variadic one. Additional arguments to the macro after the .Fa name parameter are passed as the second and subsequent arguments to each registered callback function. .It Fn EVENTHANDLER_LIST_DEFINE This macro defines a reference to an event handler list named by argument .Fa name . It uses .Xr SYSINIT 9 to initialize the reference and the eventhandler list. .It Fn EVENTHANDLER_LIST_DECLARE This macro declares an event handler list named by argument .Fa name . This is only needed for users of .Fn EVENTHANDLER_DIRECT_INVOKE which are not in the same compilation unit of that list's definition. .It Fn EVENTHANDLER_DIRECT_INVOKE This macro invokes the event handlers registered for the list named by argument .Fa name . This macro can only be used if the list was defined with .Fn EVENTHANDLER_LIST_DEFINE . The macro is variadic with the same semantics as .Fn EVENTHANDLER_INVOKE . .El .Pp The macros are implemented using the following functions: .Bl -tag -width indent .It Fn eventhandler_register The .Fn eventhandler_register function is used to register a callback with a given event. The arguments expected by this function are: .Bl -tag -width ".Fa priority" .It Fa list A pointer to an existing event handler list, or .Dv NULL . If .Fa list is .Dv NULL , the event handler list corresponding to argument .Fa name is used. .It Fa name The name of the event handler list. .It Fa func A pointer to a callback function. Argument .Fa arg is passed to the callback function .Fa func as its first argument when it is invoked. .It Fa priority The relative priority of this callback among all the callbacks registered for this event. Valid values are those in the range .Dv EVENTHANDLER_PRI_FIRST to .Dv EVENTHANDLER_PRI_LAST . .El .Pp The .Fn eventhandler_register function returns a .Fa tag that can later be used with .Fn eventhandler_deregister to remove the particular callback function. .It Fn eventhandler_deregister The .Fn eventhandler_deregister function removes the callback associated with tag .Fa tag from the event handler list pointed to by .Fa list . If .Fa tag is .Va 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 function is not safe to call from inside an event handler callback. .It Fn eventhandler_deregister_nowait The .Fn eventhandler_deregister function removes the callback associated with tag .Fa tag from the event handler list pointed to by .Fa list . This function is safe to call from inside an event handler callback. .It Fn eventhandler_find_list The .Fn eventhandler_find_list function returns a pointer to event handler list structure corresponding to event .Fa name . .It Fn eventhandler_prune_list The .Fn eventhandler_prune_list function removes all deregistered callbacks from the event list .Fa list . .El .Ss Kernel Event Handlers The following event handlers are present in the kernel: .Bl -tag -width indent .It Vt acpi_sleep_event Callbacks invoked when the system is being sent to sleep. .It Vt acpi_wakeup_event Callbacks invoked when the system is being woken up. .It Vt app_coredump_start Callbacks invoked at start of application core dump. .It Vt app_coredump_progress Callbacks invoked during progress of application core dump. .It Vt app_coredump_finish Callbacks invoked at finish of application core dump. .It Vt app_coredump_error Callbacks invoked on error of application core dump. .It Vt bpf_track Callbacks invoked when a BPF listener attaches to/detaches from network interface. .It Vt cpufreq_levels_changed Callback invoked when cpu frequency levels have changed. .It Vt cpufreq_post_change Callback invoked after cpu frequency has changed. .It Vt cpufreq_pre_change Callback invoked before cpu frequency has changed. .It Vt dcons_poll Callback invoked to poll for dcons changes. +.It Vt device_attach +Callback invoked after a device has attached. +.It Vt device_detach +Callbacks invoked before and after a device has detached. .It Vt dev_clone Callbacks invoked when a new entry is created under .Pa /dev . .It Vt group_attach_event Callback invoked when an interfance has been added to an interface group. .It Vt group_change_event Callback invoked when an change has been made to an interface group. .It Vt group_detach_event Callback invoked when an interfance has been removed from an interface group. .It Vt ifaddr_event Callbacks invoked when an address is set up on a network interface. .It Vt if_clone_event Callbacks invoked when an interface is cloned. .It Vt iflladdr_event Callback invoked when an if link layer address event has happened. .It Vt ifnet_arrival_event Callbacks invoked when a new network interface appears. .It Vt ifnet_departure_event Callbacks invoked when a network interface is taken down. .It Vt ifnet_link_event Callback invoked when an interfance link event has happened. .It Vt kld_load Callbacks invoked after a linker file has been loaded. .It Vt kld_unload Callbacks invoked after a linker file has been successfully unloaded. .It Vt 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. .It Vt lle_event Callback invoked when an link layer event has happened. .It Vt nmbclusters_change Callback invoked when the number of mbuf clusters has changed. .It Vt nmbufs_change Callback invoked when the number of mbufs has changed. .It Vt maxsockets_change Callback invoked when the maximum number of sockets has changed. .It Vt mountroot Callback invoked when root has been mounted. .It Vt power_profile_change Callbacks invoked when the power profile of the system changes. .It Vt power_resume Callback invoked when the system has resumed. .It Vt power_suspend Callback invoked just before the system is suspended. .It Vt process_ctor Callback invoked when a process is created. .It Vt process_dtor Callback invoked when a process is destroyed. .It Vt process_exec Callbacks invoked when a process performs an .Fn exec operation. .It Vt process_exit Callbacks invoked when a process exits. .It Vt process_fini Callback invoked when a process memory is destroyed. This is never called. .It Vt process_fork Callbacks invoked when a process forks a child. .It Vt process_init Callback invoked when a process is initialized. .It Vt random_adaptor_attach Callback invoked when a new random module has been loaded. .It Vt register_framebuffer Callback invoked when a new frame buffer is registered. .It Vt route_redirect_event Callback invoked when a route gets redirected to a new location. .It Vt shutdown_pre_sync Callbacks invoked at shutdown time, before file systems are synchronized. .It Vt shutdown_post_sync Callbacks invoked at shutdown time, after all file systems are synchronized. .It Vt shutdown_final Callbacks invoked just before halting the system. .It Vt tcp_offload_listen_start Callback invoked for TCP Offload to start listening for new connections. .It Vt tcp_offload_listen_stop Callback invoked ror TCP Offload to stop listening for new connections. .It Vt thread_ctor Callback invoked when a thread object is created. .It Vt thread_dtor Callback invoked when a thread object is destroyed. .It Vt thread_init Callback invoked when a thread object is initialized. .It Vt thread_fini Callback invoked when a thread object is deinitalized. .It Vt usb_dev_configured Callback invoked when a USB device is configured .It Vt unregister_framebuffer Callback invoked when a frame buffer is deregistered. .It Vt vfs_mounted Callback invoked when a file system is mounted. .It Vt vfs_unmounted Callback invoked when a file system is unmounted. .It Vt vlan_config Callback invoked when the vlan configuration has changed. .It Vt vlan_unconfig Callback invoked when a vlan is destroyed. .It Vt vm_lowmem Callbacks invoked when virtual memory is low. .It Vt watchdog_list Callbacks invoked when the system watchdog timer is reinitialized. .El .Sh RETURN VALUES The macro .Fn EVENTHANDLER_REGISTER and function .Fn eventhandler_register return a cookie of type .Vt eventhandler_tag , which may be used in a subsequent call to .Fn EVENTHANDLER_DEREGISTER or .Fn eventhandler_deregister . .Pp The .Fn eventhandler_find_list function returns a pointer to an event handler list corresponding to parameter .Fa name , or .Dv NULL if no such list was found. .Sh HISTORY The .Nm facility first appeared in .Fx 4.0 . .Sh AUTHORS This manual page was written by .An Joseph Koshy Aq Mt jkoshy@FreeBSD.org and .An Matt Joras Aq Mt mjoras@FreeBSD.org .