fs/xfs/support/ktrace.c

   1 /*
   2  * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18 #include <xfs.h>
  19
  20 static kmem_zone_t *ktrace_hdr_zone;
  21 static kmem_zone_t *ktrace_ent_zone;
  22 static int          ktrace_zentries;
  23
  24 void __init
  25 ktrace_init(int zentries)
  26 {
  27         ktrace_zentries = roundup_pow_of_two(zentries);
  28
  29         ktrace_hdr_zone = kmem_zone_init(sizeof(ktrace_t),
  30                                         "ktrace_hdr");
  31         ASSERT(ktrace_hdr_zone);
  32
  33         ktrace_ent_zone = kmem_zone_init(ktrace_zentries
  34                                         * sizeof(ktrace_entry_t),
  35                                         "ktrace_ent");
  36         ASSERT(ktrace_ent_zone);
  37 }
  38
  39 void __exit
  40 ktrace_uninit(void)
  41 {
  42         kmem_zone_destroy(ktrace_hdr_zone);
  43         kmem_zone_destroy(ktrace_ent_zone);
  44 }
  45
  46 /*
  47  * ktrace_alloc()
  48  *
  49  * Allocate a ktrace header and enough buffering for the given
  50  * number of entries. Round the number of entries up to a
  51  * power of 2 so we can do fast masking to get the index from
  52  * the atomic index counter.
  53  */
  54 ktrace_t *
  55 ktrace_alloc(int nentries, unsigned int __nocast sleep)
  56 {
  57         ktrace_t        *ktp;
  58         ktrace_entry_t  *ktep;
  59         int             entries;
  60
  61         ktp = (ktrace_t*)kmem_zone_alloc(ktrace_hdr_zone, sleep);
  62
  63         if (ktp == (ktrace_t*)NULL) {
  64                 /*
  65                  * KM_SLEEP callers don't expect failure.
  66                  */
  67                 if (sleep & KM_SLEEP)
  68                         panic("ktrace_alloc: NULL memory on KM_SLEEP request!");
  69
  70                 return NULL;
  71         }
  72
  73         /*
  74          * Special treatment for buffers with the ktrace_zentries entries
  75          */
  76         entries = roundup_pow_of_two(nentries);
  77         if (entries == ktrace_zentries) {
  78                 ktep = (ktrace_entry_t*)kmem_zone_zalloc(ktrace_ent_zone,
  79                                                             sleep);
  80         } else {
  81                 ktep = (ktrace_entry_t*)kmem_zalloc((entries * sizeof(*ktep)),
  82                                                             sleep | KM_LARGE);
  83         }
  84
  85         if (ktep == NULL) {
  86                 /*
  87                  * KM_SLEEP callers don't expect failure.
  88                  */
  89                 if (sleep & KM_SLEEP)
  90                         panic("ktrace_alloc: NULL memory on KM_SLEEP request!");
  91
  92                 kmem_free(ktp, sizeof(*ktp));
  93
  94                 return NULL;
  95         }
  96
  97         ktp->kt_entries  = ktep;
  98         ktp->kt_nentries = entries;
  99         ASSERT(is_power_of_2(entries));
 100         ktp->kt_index_mask = entries - 1;
 101         atomic_set(&ktp->kt_index, 0);
 102         ktp->kt_rollover = 0;
 103         return ktp;
 104 }
 105
 106
 107 /*
 108  * ktrace_free()
 109  *
 110  * Free up the ktrace header and buffer.  It is up to the caller
 111  * to ensure that no-one is referencing it.
 112  */
 113 void
 114 ktrace_free(ktrace_t *ktp)
 115 {
 116         int     entries_size;
 117
 118         if (ktp == (ktrace_t *)NULL)
 119                 return;
 120
 121         /*
 122          * Special treatment for the Vnode trace buffer.
 123          */
 124         if (ktp->kt_nentries == ktrace_zentries) {
 125                 kmem_zone_free(ktrace_ent_zone, ktp->kt_entries);
 126         } else {
 127                 entries_size = (int)(ktp->kt_nentries * sizeof(ktrace_entry_t));
 128
 129                 kmem_free(ktp->kt_entries, entries_size);
 130         }
 131
 132         kmem_zone_free(ktrace_hdr_zone, ktp);
 133 }
 134
 135
 136 /*
 137  * Enter the given values into the "next" entry in the trace buffer.
 138  * kt_index is always the index of the next entry to be filled.
 139  */
 140 void
 141 ktrace_enter(
 142         ktrace_t        *ktp,
 143         void            *val0,
 144         void            *val1,
 145         void            *val2,
 146         void            *val3,
 147         void            *val4,
 148         void            *val5,
 149         void            *val6,
 150         void            *val7,
 151         void            *val8,
 152         void            *val9,
 153         void            *val10,
 154         void            *val11,
 155         void            *val12,
 156         void            *val13,
 157         void            *val14,
 158         void            *val15)
 159 {
 160         int             index;
 161         ktrace_entry_t  *ktep;
 162
 163         ASSERT(ktp != NULL);
 164
 165         /*
 166          * Grab an entry by pushing the index up to the next one.
 167          */
 168         index = atomic_add_return(1, &ktp->kt_index);
 169         index = (index - 1) & ktp->kt_index_mask;
 170         if (!ktp->kt_rollover && index == ktp->kt_nentries - 1)
 171                 ktp->kt_rollover = 1;
 172
 173         ASSERT((index >= 0) && (index < ktp->kt_nentries));
 174
 175         ktep = &(ktp->kt_entries[index]);
 176
 177         ktep->val[0]  = val0;
 178         ktep->val[1]  = val1;
 179         ktep->val[2]  = val2;
 180         ktep->val[3]  = val3;
 181         ktep->val[4]  = val4;
 182         ktep->val[5]  = val5;
 183         ktep->val[6]  = val6;
 184         ktep->val[7]  = val7;
 185         ktep->val[8]  = val8;
 186         ktep->val[9]  = val9;
 187         ktep->val[10] = val10;
 188         ktep->val[11] = val11;
 189         ktep->val[12] = val12;
 190         ktep->val[13] = val13;
 191         ktep->val[14] = val14;
 192         ktep->val[15] = val15;
 193 }
 194
 195 /*
 196  * Return the number of entries in the trace buffer.
 197  */
 198 int
 199 ktrace_nentries(
 200         ktrace_t        *ktp)
 201 {
 202         int     index;
 203         if (ktp == NULL)
 204                 return 0;
 205
 206         index = atomic_read(&ktp->kt_index) & ktp->kt_index_mask;
 207         return (ktp->kt_rollover ? ktp->kt_nentries : index);
 208 }
 209
 210 /*
 211  * ktrace_first()
 212  *
 213  * This is used to find the start of the trace buffer.
 214  * In conjunction with ktrace_next() it can be used to
 215  * iterate through the entire trace buffer.  This code does
 216  * not do any locking because it is assumed that it is called
 217  * from the debugger.
 218  *
 219  * The caller must pass in a pointer to a ktrace_snap
 220  * structure in which we will keep some state used to
 221  * iterate through the buffer.  This state must not touched
 222  * by any code outside of this module.
 223  */
 224 ktrace_entry_t *
 225 ktrace_first(ktrace_t   *ktp, ktrace_snap_t     *ktsp)
 226 {
 227         ktrace_entry_t  *ktep;
 228         int             index;
 229         int             nentries;
 230
 231         if (ktp->kt_rollover)
 232                 index = atomic_read(&ktp->kt_index) & ktp->kt_index_mask;
 233         else
 234                 index = 0;
 235
 236         ktsp->ks_start = index;
 237         ktep = &(ktp->kt_entries[index]);
 238
 239         nentries = ktrace_nentries(ktp);
 240         index++;
 241         if (index < nentries) {
 242                 ktsp->ks_index = index;
 243         } else {
 244                 ktsp->ks_index = 0;
 245                 if (index > nentries)
 246                         ktep = NULL;
 247         }
 248         return ktep;
 249 }
 250
 251 /*
 252  * ktrace_next()
 253  *
 254  * This is used to iterate through the entries of the given
 255  * trace buffer.  The caller must pass in the ktrace_snap_t
 256  * structure initialized by ktrace_first().  The return value
 257  * will be either a pointer to the next ktrace_entry or NULL
 258  * if all of the entries have been traversed.
 259  */
 260 ktrace_entry_t *
 261 ktrace_next(
 262         ktrace_t        *ktp,
 263         ktrace_snap_t   *ktsp)
 264 {
 265         int             index;
 266         ktrace_entry_t  *ktep;
 267
 268         index = ktsp->ks_index;
 269         if (index == ktsp->ks_start) {
 270                 ktep = NULL;
 271         } else {
 272                 ktep = &ktp->kt_entries[index];
 273         }
 274
 275         index++;
 276         if (index == ktrace_nentries(ktp)) {
 277                 ktsp->ks_index = 0;
 278         } else {
 279                 ktsp->ks_index = index;
 280         }
 281
 282         return ktep;
 283 }
 284
 285 /*
 286  * ktrace_skip()
 287  *
 288  * Skip the next "count" entries and return the entry after that.
 289  * Return NULL if this causes us to iterate past the beginning again.
 290  */
 291 ktrace_entry_t *
 292 ktrace_skip(
 293         ktrace_t        *ktp,
 294         int             count,
 295         ktrace_snap_t   *ktsp)
 296 {
 297         int             index;
 298         int             new_index;
 299         ktrace_entry_t  *ktep;
 300         int             nentries = ktrace_nentries(ktp);
 301
 302         index = ktsp->ks_index;
 303         new_index = index + count;
 304         while (new_index >= nentries) {
 305                 new_index -= nentries;
 306         }
 307         if (index == ktsp->ks_start) {
 308                 /*
 309                  * We've iterated around to the start, so we're done.
 310                  */
 311                 ktep = NULL;
 312         } else if ((new_index < index) && (index < ktsp->ks_index)) {
 313                 /*
 314                  * We've skipped past the start again, so we're done.
 315                  */
 316                 ktep = NULL;
 317                 ktsp->ks_index = ktsp->ks_start;
 318         } else {
 319                 ktep = &(ktp->kt_entries[new_index]);
 320                 new_index++;
 321                 if (new_index == nentries) {
 322                         ktsp->ks_index = 0;
 323                 } else {
 324                         ktsp->ks_index = new_index;
 325                 }
 326         }
 327         return ktep;
 328 }