bsd/sys/eventhandler.h

   1 /*
   2  * Copyright (c) 2016-2017 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*-
  29  * Copyright (c) 1999 Michael Smith <msmith@freebsd.org>
  30  * All rights reserved.
  31  *
  32  * Redistribution and use in source and binary forms, with or without
  33  * modification, are permitted provided that the following conditions
  34  * are met:
  35  * 1. Redistributions of source code must retain the above copyright
  36  *    notice, this list of conditions and the following disclaimer.
  37  * 2. Redistributions in binary form must reproduce the above copyright
  38  *    notice, this list of conditions and the following disclaimer in the
  39  *    documentation and/or other materials provided with the distribution.
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  *
  53  * $FreeBSD$
  54  */
  55
  56 #ifndef _SYS_EVENTHANDLER_H_
  57 #define _SYS_EVENTHANDLER_H_
  58
  59 #include <kern/locks.h>
  60 #include <sys/queue.h>
  61 #include <sys/cdefs.h>
  62 #include <sys/syslog.h>
  63 #include <uuid/uuid.h>
  64
  65 extern int evh_debug;
  66 extern lck_grp_t        *el_lock_grp;
  67 extern lck_attr_t       *el_lock_attr;
  68 extern struct eventhandler_entry_arg eventhandler_entry_dummy_arg;
  69
  70 struct eventhandler_lists_ctxt {
  71         TAILQ_HEAD(, eventhandler_list)  eventhandler_lists;
  72         int eventhandler_lists_initted;
  73         decl_lck_mtx_data(, eventhandler_mutex);
  74 };
  75
  76 struct eventhandler_entry_arg {
  77         union {
  78                 /* Generic cookie object reference */
  79                 void            *ee_voidptr;
  80                 /* Skywalk ids */
  81                 struct {
  82                         pid_t           ee_fe_pid;
  83                         uuid_t          ee_fe_uuid;
  84                         uuid_t          ee_nx_uuid;
  85                 } sk_ids;
  86                 /* Generic UUID */
  87                 uuid_t          ee_uuid;
  88         } ee_arg;
  89 };
  90
  91 #define ee_voidptr      ee_arg.ee_voidptr
  92 #define ee_fe_pid       ee_arg.sk_ids.ee_fe_pid
  93 #define ee_fe_uuid      ee_arg.sk_ids.ee_fe_uuid
  94 #define ee_nx_uuid      ee_arg.sk_ids.ee_nx_uuid
  95 #define ee_uuid         ee_arg.ee_uuid
  96
  97 struct eventhandler_entry {
  98         TAILQ_ENTRY(eventhandler_entry) ee_link;
  99         int                             ee_priority;
 100 #define EHE_DEAD_PRIORITY       (-1)
 101         struct eventhandler_entry_arg   ee_arg;
 102 };
 103
 104 struct eventhandler_list {
 105         char                            *el_name;
 106         int                             el_flags;
 107 #define EHL_INITTED     (1<<0)
 108         u_int                           el_runcount;
 109         decl_lck_mtx_data(, el_lock);
 110         TAILQ_ENTRY(eventhandler_list)  el_link;
 111         TAILQ_HEAD(,eventhandler_entry) el_entries;
 112 };
 113
 114 typedef struct eventhandler_entry       *eventhandler_tag;
 115
 116 #define EHL_LOCK_INIT(p)        lck_mtx_init(&(p)->el_lock, el_lock_grp, el_lock_attr)
 117 #define EHL_LOCK(p)             lck_mtx_lock(&(p)->el_lock)
 118 #define EHL_UNLOCK(p)           lck_mtx_unlock(&(p)->el_lock)
 119 #define EHL_LOCK_ASSERT(p, x)   LCK_MTX_ASSERT(&(p)->el_lock, x)
 120 #define EHL_LOCK_DESTROY(p)     lck_mtx_destroy(&(p)->el_lock, el_lock_grp)
 121
 122 #define evhlog(x)       do { if (evh_debug >= 1) log x; } while (0)
 123
 124 /*
 125  * Macro to invoke the handlers for a given event.
 126  */
 127 #define _EVENTHANDLER_INVOKE(name, list, ...) do {                      \
 128         struct eventhandler_entry *_ep;                                 \
 129         struct eventhandler_entry_ ## name *_t;                         \
 130                                                                         \
 131         VERIFY((list)->el_flags & EHL_INITTED);                         \
 132         EHL_LOCK_ASSERT((list), LCK_MTX_ASSERT_OWNED);                  \
 133         (list)->el_runcount++;                                          \
 134         VERIFY((list)->el_runcount > 0);                                \
 135         evhlog((LOG_DEBUG, "eventhandler_invoke(\"" __STRING(name) "\")"));     \
 136         TAILQ_FOREACH(_ep, &((list)->el_entries), ee_link) {            \
 137                 if (_ep->ee_priority != EHE_DEAD_PRIORITY) {            \
 138                         EHL_UNLOCK((list));                             \
 139                         _t = (struct eventhandler_entry_ ## name *)_ep; \
 140                         evhlog((LOG_DEBUG, "eventhandler_invoke: executing %p", \
 141                             VM_KERNEL_UNSLIDE((void *)_t->eh_func)));   \
 142                         _t->eh_func(_ep->ee_arg , ## __VA_ARGS__);      \
 143                         EHL_LOCK((list));                               \
 144                 }                                                       \
 145         }                                                               \
 146         KASSERT((list)->el_runcount > 0,                                \
 147             ("eventhandler_invoke: runcount underflow"));               \
 148         (list)->el_runcount--;                                          \
 149         if ((list)->el_runcount == 0)                                   \
 150                 eventhandler_prune_list(list);                          \
 151         EHL_UNLOCK((list));                                             \
 152 } while (0)
 153
 154 /*
 155  * Slow handlers are entirely dynamic; lists are created
 156  * when entries are added to them, and thus have no concept of "owner",
 157  *
 158  * Slow handlers need to be declared, but do not need to be defined. The
 159  * declaration must be in scope wherever the handler is to be invoked.
 160  */
 161 #define EVENTHANDLER_DECLARE(name, type)                                \
 162 struct eventhandler_entry_ ## name                                      \
 163 {                                                                       \
 164         struct eventhandler_entry       ee;                             \
 165         type                            eh_func;                        \
 166 };                                                                      \
 167 struct __hack
 168
 169 /*
 170  * XXX EVENTHANDLER_DEFINE by itself doesn't do much on XNU
 171  * All it does is that it declares the static eventhandler_tag
 172  * and defines an init routine that still needs to called to put the
 173  * event and callback on the list.
 174  */
 175 #define EVENTHANDLER_DEFINE(evthdlr_ref, name, func, arg, priority)                     \
 176         static eventhandler_tag name ## _tag;                           \
 177         static void name ## _evh_init(void *ctx)                        \
 178         {                                                               \
 179                 name ## _tag = EVENTHANDLER_REGISTER(evthdlr_ref, name, func, ctx,      \
 180                     priority);                                          \
 181         }                                                               \
 182         SYSINIT(name ## _evh_init, SI_SUB_CONFIGURE, SI_ORDER_ANY,      \
 183             name ## _evh_init, arg);                                    \
 184         struct __hack
 185
 186 #define EVENTHANDLER_INVOKE(evthdlr_ref, name, ...)                                     \
 187 do {                                                                    \
 188         struct eventhandler_list *_el;                                  \
 189                                                                         \
 190         if ((_el = eventhandler_find_list(evthdlr_ref, #name)) != NULL)                 \
 191                 _EVENTHANDLER_INVOKE(name, _el , ## __VA_ARGS__);       \
 192 } while (0)
 193
 194 #define EVENTHANDLER_REGISTER(evthdlr_ref, name, func, arg, priority)           \
 195         eventhandler_register(evthdlr_ref, NULL, #name, func, arg, priority)
 196
 197 #define EVENTHANDLER_DEREGISTER(evthdlr_ref, name, tag)                                 \
 198 do {                                                                    \
 199         struct eventhandler_list *_el;                                  \
 200                                                                         \
 201         if ((_el = eventhandler_find_list(evthdlr_ref, #name)) != NULL)         \
 202                 eventhandler_deregister(_el, tag);                      \
 203 } while(0)
 204
 205 void eventhandler_init(void);
 206 eventhandler_tag eventhandler_register(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt,
 207     struct eventhandler_list *list, const char *name, void *func, struct eventhandler_entry_arg arg, int priority);
 208 void eventhandler_deregister(struct eventhandler_list *list,
 209     eventhandler_tag tag);
 210 struct eventhandler_list *eventhandler_find_list(
 211     struct eventhandler_lists_ctxt *evthdlr_lists_ctxt, const char *name);
 212 void eventhandler_prune_list(struct eventhandler_list *list);
 213 void eventhandler_lists_ctxt_init(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt);
 214 void eventhandler_lists_ctxt_destroy(struct eventhandler_lists_ctxt *evthdlr_lists_ctxt);
 215
 216 /* Generic priority levels */
 217 #define EVENTHANDLER_PRI_FIRST  0
 218 #define EVENTHANDLER_PRI_ANY    10000
 219 #define EVENTHANDLER_PRI_LAST   20000
 220
 221 #endif /* _SYS_EVENTHANDLER_H_ */