sys/sys/eventhandler.h

   1 /*-
   2  * Copyright (c) 1999 Michael Smith <msmith@freebsd.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD$
  27  */
  28
  29 #ifndef SYS_EVENTHANDLER_H
  30 #define SYS_EVENTHANDLER_H
  31
  32 #include <sys/lock.h>
  33 #include <sys/ktr.h>
  34 #include <sys/mutex.h>
  35 #include <sys/queue.h>
  36
  37 struct eventhandler_entry {
  38         TAILQ_ENTRY(eventhandler_entry) ee_link;
  39         int                             ee_priority;
  40 #define EHE_DEAD_PRIORITY       (-1)
  41         void                            *ee_arg;
  42 };
  43
  44 struct eventhandler_list {
  45         char                            *el_name;
  46         int                             el_flags;
  47 #define EHL_INITTED     (1<<0)
  48         u_int                           el_runcount;
  49         struct mtx                      el_lock;
  50         TAILQ_ENTRY(eventhandler_list)  el_link;
  51         TAILQ_HEAD(,eventhandler_entry) el_entries;
  52 };
  53
  54 typedef struct eventhandler_entry       *eventhandler_tag;
  55
  56 #define EHL_LOCK(p)             mtx_lock(&(p)->el_lock)
  57 #define EHL_UNLOCK(p)           mtx_unlock(&(p)->el_lock)
  58 #define EHL_LOCK_ASSERT(p, x)   mtx_assert(&(p)->el_lock, x)
  59
  60 /*
  61  * Macro to invoke the handlers for a given event.
  62  */
  63 #define _EVENTHANDLER_INVOKE(name, list, ...) do {                      \
  64         struct eventhandler_entry *_ep;                                 \
  65         struct eventhandler_entry_ ## name *_t;                         \
  66                                                                         \
  67         KASSERT((list)->el_flags & EHL_INITTED,                         \
  68            ("eventhandler_invoke: running non-inited list"));           \
  69         EHL_LOCK_ASSERT((list), MA_OWNED);                              \
  70         (list)->el_runcount++;                                          \
  71         KASSERT((list)->el_runcount > 0,                                \
  72             ("eventhandler_invoke: runcount overflow"));                \
  73         CTR0(KTR_EVH, "eventhandler_invoke(\"" __STRING(name) "\")");   \
  74         TAILQ_FOREACH(_ep, &((list)->el_entries), ee_link) {            \
  75                 if (_ep->ee_priority != EHE_DEAD_PRIORITY) {            \
  76                         EHL_UNLOCK((list));                             \
  77                         _t = (struct eventhandler_entry_ ## name *)_ep; \
  78                         CTR1(KTR_EVH, "eventhandler_invoke: executing %p", \
  79                             (void *)_t->eh_func);                       \
  80                         _t->eh_func(_ep->ee_arg , ## __VA_ARGS__);      \
  81                         EHL_LOCK((list));                               \
  82                 }                                                       \
  83         }                                                               \
  84         KASSERT((list)->el_runcount > 0,                                \
  85             ("eventhandler_invoke: runcount underflow"));               \
  86         (list)->el_runcount--;                                          \
  87         if ((list)->el_runcount == 0)                                   \
  88                 eventhandler_prune_list(list);                          \
  89         EHL_UNLOCK((list));                                             \
  90 } while (0)
  91
  92 /*
  93  * Slow handlers are entirely dynamic; lists are created
  94  * when entries are added to them, and thus have no concept of "owner",
  95  *
  96  * Slow handlers need to be declared, but do not need to be defined. The
  97  * declaration must be in scope wherever the handler is to be invoked.
  98  */
  99 #define EVENTHANDLER_DECLARE(name, type)                                \
 100 struct eventhandler_entry_ ## name                                      \
 101 {                                                                       \
 102         struct eventhandler_entry       ee;                             \
 103         type                            eh_func;                        \
 104 };                                                                      \
 105 struct __hack
 106
 107 #define EVENTHANDLER_INVOKE(name, ...)                                  \
 108 do {                                                                    \
 109         struct eventhandler_list *_el;                                  \
 110                                                                         \
 111         if ((_el = eventhandler_find_list(#name)) != NULL)              \
 112                 _EVENTHANDLER_INVOKE(name, _el , ## __VA_ARGS__);       \
 113 } while (0)
 114
 115 #define EVENTHANDLER_REGISTER(name, func, arg, priority)                \
 116         eventhandler_register(NULL, #name, func, arg, priority)
 117
 118 #define EVENTHANDLER_DEREGISTER(name, tag)                              \
 119 do {                                                                    \
 120         struct eventhandler_list *_el;                                  \
 121                                                                         \
 122         if ((_el = eventhandler_find_list(#name)) != NULL)              \
 123                 eventhandler_deregister(_el, tag);                      \
 124 } while(0)
 125
 126
 127 eventhandler_tag eventhandler_register(struct eventhandler_list *list,
 128             const char *name, void *func, void *arg, int priority);
 129 void    eventhandler_deregister(struct eventhandler_list *list,
 130             eventhandler_tag tag);
 131 struct eventhandler_list *eventhandler_find_list(const char *name);
 132 void    eventhandler_prune_list(struct eventhandler_list *list);
 133
 134 /*
 135  * Standard system event queues.
 136  */
 137
 138 /* Generic priority levels */
 139 #define EVENTHANDLER_PRI_FIRST  0
 140 #define EVENTHANDLER_PRI_ANY    10000
 141 #define EVENTHANDLER_PRI_LAST   20000
 142
 143 /* Shutdown events */
 144 typedef void (*shutdown_fn)(void *, int);
 145
 146 #define SHUTDOWN_PRI_FIRST      EVENTHANDLER_PRI_FIRST
 147 #define SHUTDOWN_PRI_DEFAULT    EVENTHANDLER_PRI_ANY
 148 #define SHUTDOWN_PRI_LAST       EVENTHANDLER_PRI_LAST
 149
 150 EVENTHANDLER_DECLARE(shutdown_pre_sync, shutdown_fn);   /* before fs sync */
 151 EVENTHANDLER_DECLARE(shutdown_post_sync, shutdown_fn);  /* after fs sync */
 152 EVENTHANDLER_DECLARE(shutdown_final, shutdown_fn);
 153
 154 /* Low memory event */
 155 typedef void (*vm_lowmem_handler_t)(void *, int);
 156 #define LOWMEM_PRI_DEFAULT      EVENTHANDLER_PRI_FIRST
 157 EVENTHANDLER_DECLARE(vm_lowmem, vm_lowmem_handler_t);
 158
 159 /*
 160  * Process events
 161  * process_fork and exit handlers are called without Giant.
 162  * exec handlers are called with Giant, but that is by accident.
 163  */
 164 struct proc;
 165
 166 typedef void (*exitlist_fn)(void *, struct proc *);
 167 typedef void (*forklist_fn)(void *, struct proc *, struct proc *, int);
 168 typedef void (*execlist_fn)(void *, struct proc *);
 169
 170 EVENTHANDLER_DECLARE(process_exit, exitlist_fn);
 171 EVENTHANDLER_DECLARE(process_fork, forklist_fn);
 172 EVENTHANDLER_DECLARE(process_exec, execlist_fn);
 173
 174 #endif /* SYS_EVENTHANDLER_H */