The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/sys/eventhandler.h

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    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: src/sys/sys/eventhandler.h,v 1.32 2004/03/14 02:06:28 peter Exp $
   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             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(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 */

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