osfmk/kern/etap_pool.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * @OSF_COPYRIGHT@
  27  */
  28 /*
  29  * HISTORY
  30  *
  31  * Revision 1.1.1.1  1998/09/22 21:05:34  wsanchez
  32  * Import of Mac OS X kernel (~semeria)
  33  *
  34  * Revision 1.1.1.1  1998/03/07 02:25:54  wsanchez
  35  * Import of OSF Mach kernel (~mburg)
  36  *
  37  * Revision 1.1.12.1  1996/09/17  16:27:00  bruel
  38  *      fixed bzero prototype.
  39  *      [96/09/17            bruel]
  40  *
  41  * Revision 1.1.2.4  1995/10/09  17:13:51  devrcs
  42  *      Merged in RT3_SHARED ETAP code.
  43  *      [1995/09/13  18:34:15  joe]
  44  *
  45  * Revision 1.1.2.3  1995/09/18  19:13:37  devrcs
  46  *      Merged in RT3_SHARED ETAP code.
  47  *      [1995/09/13  18:34:15  joe]
  48  *
  49  * Revision 1.1.2.2  1995/01/10  05:11:15  devrcs
  50  *      mk6 CR801 - merge up from nmk18b4 to nmk18b7
  51  *      patch up spinlock references ==> simplelock
  52  *      [1994/12/09  20:54:30  dwm]
  53  *
  54  *      mk6 CR801 - new file for mk6_shared from cnmk_shared.
  55  *      [1994/12/01  21:11:49  dwm]
  56  *
  57  * Revision 1.1.2.1  1994/10/21  18:28:50  joe
  58  *      Initial ETAP submission
  59  *      [1994/10/20  19:31:33  joe]
  60  *
  61  * $EndLog$
  62  */
  63 /*
  64  * File:       etap_pool.c
  65  *
  66  *             etap_pool.c contains the functions for maintenance
  67  *             of the start_data_pool.   The start_data_pool is
  68  *             used by the ETAP package.  Its primary
  69  *             objective is to provide start_data_nodes to complex
  70  *             locks so they can hold start information for read
  71  *             locks  (since multiple readers can acquire a read
  72  *             lock).   Each complex lock will maintain a linked
  73  *             list of these nodes.
  74  *
  75  * NOTES:      The start_data_pool is used instead of zalloc to
  76  *             eliminate complex lock dependancies.  If zalloc was used,
  77  *             then no complex locks could be used in zalloc code paths.
  78  *             This is both difficult and unrealistic, since zalloc
  79  *             allocates memory dynamically. Hence, this dependancy is
  80  *             eliminated with the use of the statically allocated
  81  *             start_data_pool.
  82  *
  83  */
  84
  85 #include <kern/lock.h>
  86 #include <kern/spl.h>
  87 #include <kern/etap_pool.h>
  88 #include <kern/sched_prim.h>
  89 #include <kern/macro_help.h>
  90
  91 #if     ETAP_LOCK_TRACE
  92
  93 /*
  94  *  Statically allocate the start data pool,
  95  *  header and lock.
  96  */
  97
  98 struct start_data_node  sd_pool [SD_POOL_ENTRIES];  /* static buffer */
  99 start_data_node_t       sd_free_list;   /* pointer to free node list */
 100 int                     sd_sleepers;    /* number of blocked threads */
 101
 102 simple_lock_data_t              sd_pool_lock;
 103
 104
 105 /*
 106  *  Interrupts must be disabled while the
 107  *  sd_pool_lock is taken.
 108  */
 109
 110 #define pool_lock(s)                    \
 111 MACRO_BEGIN                             \
 112         s = splhigh();                  \
 113         simple_lock(&sd_pool_lock);     \
 114 MACRO_END
 115
 116 #define pool_unlock(s)                  \
 117 MACRO_BEGIN                             \
 118         simple_unlock(&sd_pool_lock);   \
 119         splx(s);                        \
 120 MACRO_END
 121
 122
 123 /*
 124  *  ROUTINE:    init_start_data_pool
 125  *
 126  *  FUNCTION:   Initialize the start_data_pool:
 127  *              - create the free list chain for the max
 128  *                number of entries.
 129  *              - initialize the sd_pool_lock
 130  */
 131
 132 void
 133 init_start_data_pool(void)
 134 {
 135         int x;
 136
 137         simple_lock_init(&sd_pool_lock, ETAP_MISC_SD_POOL);
 138
 139         /*
 140          *  Establish free list pointer chain
 141          */
 142
 143         for (x=0; x < SD_POOL_ENTRIES-1; x++)
 144                 sd_pool[x].next = &sd_pool[x+1];
 145
 146         sd_pool[SD_POOL_ENTRIES-1].next = SD_ENTRY_NULL;
 147         sd_free_list  = &sd_pool[0];
 148         sd_sleepers   = 0;
 149 }
 150
 151 /*
 152  *  ROUTINE:    get_start_data_node
 153  *
 154  *  FUNCTION:   Returns a free node from the start data pool
 155  *              to the caller.  If none are available, the
 156  *              call will block, then try again.
 157  */
 158
 159 start_data_node_t
 160 get_start_data_node(void)
 161 {
 162         start_data_node_t avail_node;
 163         spl_t             s;
 164
 165         pool_lock(s);
 166
 167         /*
 168          *  If the pool does not have any nodes available,
 169          *  block until one becomes free.
 170          */
 171
 172         while (sd_free_list == SD_ENTRY_NULL) {
 173
 174                 sd_sleepers++;
 175                 assert_wait((event_t) &sd_pool[0], THREAD_UNINT);
 176                 pool_unlock(s);
 177
 178                 printf ("DEBUG-KERNEL: empty start_data_pool\n");
 179                 thread_block(THREAD_CONTINUE_NULL);
 180
 181                 pool_lock(s);
 182                 sd_sleepers--;
 183         }
 184
 185         avail_node   = sd_free_list;
 186         sd_free_list = sd_free_list->next;
 187
 188         pool_unlock(s);
 189
 190         bzero ((char *) avail_node, sizeof(struct start_data_node));
 191         avail_node->next = SD_ENTRY_NULL;
 192
 193         return (avail_node);
 194 }
 195
 196 /*
 197  *  ROUTINE:    free_start_data_node
 198  *
 199  *  FUNCTION:   Releases start data node back to the sd_pool,
 200  *              so that it can be used again.
 201  */
 202
 203 void
 204 free_start_data_node (
 205         start_data_node_t   node)
 206 {
 207         boolean_t   wakeup = FALSE;
 208         spl_t       s;
 209
 210         if (node == SD_ENTRY_NULL)
 211                 return;
 212
 213         pool_lock(s);
 214
 215         node->next   = sd_free_list;
 216         sd_free_list = node;
 217
 218         if (sd_sleepers)
 219                 wakeup = TRUE;
 220
 221         pool_unlock(s);
 222
 223         if (wakeup)
 224                 thread_wakeup((event_t) &sd_pool[0]);
 225 }
 226
 227 #endif  /* ETAP_LOCK_TRACE */