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/kern/subr_kobj.c

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    1 /*-
    2  * Copyright (c) 2000 Doug Rabson
    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: releng/5.0/sys/kern/subr_kobj.c 98105 2002-06-10 22:40:26Z kbyanc $
   27  */
   28 
   29 #include <sys/param.h>
   30 #include <sys/queue.h>
   31 #include <sys/malloc.h>
   32 #include <sys/kernel.h>
   33 #include <sys/module.h>
   34 #include <sys/errno.h>
   35 #ifndef TEST
   36 #include <sys/systm.h>
   37 #endif
   38 #include <sys/kobj.h>
   39 
   40 #ifdef TEST
   41 #include "usertest.h"
   42 #endif
   43 
   44 static MALLOC_DEFINE(M_KOBJ, "kobj", "Kernel object structures");
   45 
   46 #ifdef KOBJ_STATS
   47 
   48 #include <sys/sysctl.h>
   49 
   50 u_int kobj_lookup_hits;
   51 u_int kobj_lookup_misses;
   52 
   53 SYSCTL_UINT(_kern, OID_AUTO, kobj_hits, CTLFLAG_RD,
   54            &kobj_lookup_hits, 0, "")
   55 SYSCTL_UINT(_kern, OID_AUTO, kobj_misses, CTLFLAG_RD,
   56            &kobj_lookup_misses, 0, "")
   57 
   58 #endif
   59 
   60 static int kobj_next_id = 1;
   61 
   62 static int
   63 kobj_error_method(void)
   64 {
   65         return ENXIO;
   66 }
   67 
   68 static void
   69 kobj_register_method(struct kobjop_desc *desc)
   70 {
   71         if (desc->id == 0)
   72                 desc->id = kobj_next_id++;
   73 }
   74 
   75 static void
   76 kobj_unregister_method(struct kobjop_desc *desc)
   77 {
   78 }
   79 
   80 static void
   81 kobj_class_compile_common(kobj_class_t cls, kobj_ops_t ops)
   82 {
   83         kobj_method_t *m;
   84         int i;
   85 
   86         /*
   87          * Don't do anything if we are already compiled.
   88          */
   89         if (cls->ops)
   90                 return;
   91 
   92         /*
   93          * First register any methods which need it.
   94          */
   95         for (i = 0, m = cls->methods; m->desc; i++, m++)
   96                 kobj_register_method(m->desc);
   97 
   98         /*
   99          * Then initialise the ops table.
  100          */
  101         bzero(ops, sizeof(struct kobj_ops));
  102         ops->cls = cls;
  103         cls->ops = ops;
  104 }
  105 
  106 void
  107 kobj_class_compile(kobj_class_t cls)
  108 {
  109         kobj_ops_t ops;
  110 
  111         /*
  112          * Allocate space for the compiled ops table.
  113          */
  114         ops = malloc(sizeof(struct kobj_ops), M_KOBJ, M_NOWAIT);
  115         if (!ops)
  116                 panic("kobj_compile_methods: out of memory");
  117         kobj_class_compile_common(cls, ops);
  118 }
  119 
  120 void
  121 kobj_class_compile_static(kobj_class_t cls, kobj_ops_t ops)
  122 {
  123         /*
  124          * Increment refs to make sure that the ops table is not freed.
  125          */
  126         cls->refs++;
  127         kobj_class_compile_common(cls, ops);
  128 }
  129 
  130 void
  131 kobj_lookup_method(kobj_method_t *methods,
  132                    kobj_method_t *ce,
  133                    kobjop_desc_t desc)
  134 {
  135         ce->desc = desc;
  136         for (; methods && methods->desc; methods++) {
  137                 if (methods->desc == desc) {
  138                         ce->func = methods->func;
  139                         return;
  140                 }
  141         }
  142         if (desc->deflt)
  143                 ce->func = desc->deflt;
  144         else
  145                 ce->func = kobj_error_method;
  146         return;
  147 }
  148 
  149 void
  150 kobj_class_free(kobj_class_t cls)
  151 {
  152         int i;
  153         kobj_method_t *m;
  154 
  155         /*
  156          * Unregister any methods which are no longer used.
  157          */
  158         for (i = 0, m = cls->methods; m->desc; i++, m++)
  159                 kobj_unregister_method(m->desc);
  160 
  161         /*
  162          * Free memory and clean up.
  163          */
  164         free(cls->ops, M_KOBJ);
  165         cls->ops = 0;
  166 }
  167 
  168 kobj_t
  169 kobj_create(kobj_class_t cls,
  170             struct malloc_type *mtype,
  171             int mflags)
  172 {
  173         kobj_t obj;
  174 
  175         /*
  176          * Allocate and initialise the new object.
  177          */
  178         obj = malloc(cls->size, mtype, mflags | M_ZERO);
  179         if (!obj)
  180                 return 0;
  181         kobj_init(obj, cls);
  182 
  183         return obj;
  184 }
  185 
  186 void
  187 kobj_init(kobj_t obj, kobj_class_t cls)
  188 {
  189         /*
  190          * Consider compiling the class' method table.
  191          */
  192         if (!cls->ops)
  193                 kobj_class_compile(cls);
  194 
  195         obj->ops = cls->ops;
  196         cls->refs++;
  197 }
  198 
  199 void
  200 kobj_delete(kobj_t obj, struct malloc_type *mtype)
  201 {
  202         kobj_class_t cls = obj->ops->cls;
  203 
  204         /*
  205          * Consider freeing the compiled method table for the class
  206          * after its last instance is deleted. As an optimisation, we
  207          * should defer this for a short while to avoid thrashing.
  208          */
  209         cls->refs--;
  210         if (!cls->refs)
  211                 kobj_class_free(cls);
  212 
  213         obj->ops = 0;
  214         if (mtype)
  215                 free(obj, mtype);
  216 }

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