liblttng-ust/lttng-probes.c

   1 /*
   2  * lttng-probes.c
   3  *
   4  * Holds LTTng probes registry.
   5  *
   6  * Copyright 2010-2012 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <string.h>
  24 #include <errno.h>
  25 #include <urcu/list.h>
  26 #include <urcu/hlist.h>
  27 #include <lttng/ust-events.h>
  28 #include <lttng/tracepoint.h>
  29 #include "tracepoint-internal.h"
  30 #include <assert.h>
  31 #include <helper.h>
  32 #include <ctype.h>
  33
  34 #include "lttng-tracer-core.h"
  35 #include "jhash.h"
  36 #include "error.h"
  37
  38 /*
  39  * probe list is protected by ust_lock()/ust_unlock().
  40  */
  41 static CDS_LIST_HEAD(_probe_list);
  42
  43 /*
  44  * List of probes registered by not yet processed.
  45  */
  46 static CDS_LIST_HEAD(lazy_probe_init);
  47
  48 /*
  49  * lazy_nesting counter ensures we don't trigger lazy probe registration
  50  * fixup while we are performing the fixup. It is protected by the ust
  51  * mutex.
  52  */
  53 static int lazy_nesting;
  54
  55 /*
  56  * Called under ust lock.
  57  */
  58 static
  59 int check_event_provider(struct lttng_probe_desc *desc)
  60 {
  61         int i;
  62         size_t provider_name_len;
  63
  64         provider_name_len = strnlen(desc->provider,
  65                                 LTTNG_UST_SYM_NAME_LEN - 1);
  66         for (i = 0; i < desc->nr_events; i++) {
  67                 if (strncmp(desc->event_desc[i]->name,
  68                                 desc->provider,
  69                                 provider_name_len))
  70                         return 0;       /* provider mismatch */
  71         }
  72         return 1;
  73 }
  74
  75 /*
  76  * Called under ust lock.
  77  */
  78 static
  79 void lttng_lazy_probe_register(struct lttng_probe_desc *desc)
  80 {
  81         struct lttng_probe_desc *iter;
  82         struct cds_list_head *probe_list;
  83         int i;
  84
  85         /*
  86          * Each provider enforce that every event name begins with the
  87          * provider name. Check this in an assertion for extra
  88          * carefulness. This ensures we cannot have duplicate event
  89          * names across providers.
  90          */
  91         assert(check_event_provider(desc));
  92
  93         /*
  94          * The provider ensures there are no duplicate event names.
  95          * Duplicated TRACEPOINT_EVENT event names would generate a
  96          * compile-time error due to duplicated symbol names.
  97          */
  98
  99         /*
 100          * We sort the providers by struct lttng_probe_desc pointer
 101          * address.
 102          */
 103         probe_list = &_probe_list;
 104         cds_list_for_each_entry_reverse(iter, probe_list, head) {
 105                 BUG_ON(iter == desc); /* Should never be in the list twice */
 106                 if (iter < desc) {
 107                         /* We belong to the location right after iter. */
 108                         cds_list_add(&desc->head, &iter->head);
 109                         goto desc_added;
 110                 }
 111         }
 112         /* We should be added at the head of the list */
 113         cds_list_add(&desc->head, probe_list);
 114 desc_added:
 115         DBG("just registered probe %s containing %u events",
 116                 desc->provider, desc->nr_events);
 117         /*
 118          * fix the events awaiting probe load.
 119          */
 120         for (i = 0; i < desc->nr_events; i++) {
 121                 const struct lttng_event_desc *ed;
 122                 int ret;
 123
 124                 ed = desc->event_desc[i];
 125                 DBG("Registered event probe \"%s\" with signature \"%s\"",
 126                         ed->name, ed->signature);
 127                 ret = lttng_fix_pending_event_desc(ed);
 128                 assert(!ret);
 129         }
 130 }
 131
 132 /*
 133  * Called under ust lock.
 134  */
 135 static
 136 void fixup_lazy_probes(void)
 137 {
 138         struct lttng_probe_desc *iter, *tmp;
 139
 140         lazy_nesting++;
 141         cds_list_for_each_entry_safe(iter, tmp,
 142                         &lazy_probe_init, lazy_init_head) {
 143                 lttng_lazy_probe_register(iter);
 144                 iter->lazy = 0;
 145                 cds_list_del(&iter->lazy_init_head);
 146         }
 147         lazy_nesting--;
 148 }
 149
 150 /*
 151  * Called under ust lock.
 152  */
 153 struct cds_list_head *lttng_get_probe_list_head(void)
 154 {
 155         if (!lazy_nesting && !cds_list_empty(&lazy_probe_init))
 156                 fixup_lazy_probes();
 157         return &_probe_list;
 158 }
 159
 160 static
 161 const struct lttng_probe_desc *find_provider(const char *provider)
 162 {
 163         struct lttng_probe_desc *iter;
 164         struct cds_list_head *probe_list;
 165
 166         probe_list = lttng_get_probe_list_head();
 167         cds_list_for_each_entry(iter, probe_list, head) {
 168                 if (!strcmp(iter->provider, provider))
 169                         return iter;
 170         }
 171         return NULL;
 172 }
 173
 174 int lttng_probe_register(struct lttng_probe_desc *desc)
 175 {
 176         int ret = 0;
 177
 178         ust_lock();
 179
 180         /*
 181          * Check if the provider has already been registered.
 182          */
 183         if (find_provider(desc->provider)) {
 184                 ret = -EEXIST;
 185                 goto end;
 186         }
 187         cds_list_add(&desc->lazy_init_head, &lazy_probe_init);
 188         desc->lazy = 1;
 189         DBG("adding probe %s containing %u events to lazy registration list",
 190                 desc->provider, desc->nr_events);
 191         /*
 192          * If there is at least one active session, we need to register
 193          * the probe immediately, since we cannot delay event
 194          * registration because they are needed ASAP.
 195          */
 196         if (lttng_session_active())
 197                 fixup_lazy_probes();
 198 end:
 199         ust_unlock();
 200         return ret;
 201 }
 202
 203 /* Backward compatibility with UST 2.0 */
 204 int ltt_probe_register(struct lttng_probe_desc *desc)
 205 {
 206         return lttng_probe_register(desc);
 207 }
 208
 209 void lttng_probe_unregister(struct lttng_probe_desc *desc)
 210 {
 211         ust_lock();
 212         if (!desc->lazy)
 213                 cds_list_del(&desc->head);
 214         else
 215                 cds_list_del(&desc->lazy_init_head);
 216         DBG("just unregistered probe %s", desc->provider);
 217         ust_unlock();
 218 }
 219
 220 /* Backward compatibility with UST 2.0 */
 221 void ltt_probe_unregister(struct lttng_probe_desc *desc)
 222 {
 223         lttng_probe_unregister(desc);
 224 }
 225
 226 void lttng_probes_prune_event_list(struct lttng_ust_tracepoint_list *list)
 227 {
 228         struct tp_list_entry *list_entry, *tmp;
 229
 230         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 231                 cds_list_del(&list_entry->head);
 232                 free(list_entry);
 233         }
 234 }
 235
 236 /*
 237  * called with UST lock held.
 238  */
 239 int lttng_probes_get_event_list(struct lttng_ust_tracepoint_list *list)
 240 {
 241         struct lttng_probe_desc *probe_desc;
 242         int i;
 243         struct cds_list_head *probe_list;
 244
 245         probe_list = lttng_get_probe_list_head();
 246         CDS_INIT_LIST_HEAD(&list->head);
 247         cds_list_for_each_entry(probe_desc, probe_list, head) {
 248                 for (i = 0; i < probe_desc->nr_events; i++) {
 249                         struct tp_list_entry *list_entry;
 250
 251                         list_entry = zmalloc(sizeof(*list_entry));
 252                         if (!list_entry)
 253                                 goto err_nomem;
 254                         cds_list_add(&list_entry->head, &list->head);
 255                         strncpy(list_entry->tp.name,
 256                                 probe_desc->event_desc[i]->name,
 257                                 LTTNG_UST_SYM_NAME_LEN);
 258                         list_entry->tp.name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 259                         if (!probe_desc->event_desc[i]->loglevel) {
 260                                 list_entry->tp.loglevel = TRACE_DEFAULT;
 261                         } else {
 262                                 list_entry->tp.loglevel = *(*probe_desc->event_desc[i]->loglevel);
 263                         }
 264                 }
 265         }
 266         if (cds_list_empty(&list->head))
 267                 list->iter = NULL;
 268         else
 269                 list->iter =
 270                         cds_list_first_entry(&list->head, struct tp_list_entry, head);
 271         return 0;
 272
 273 err_nomem:
 274         lttng_probes_prune_event_list(list);
 275         return -ENOMEM;
 276 }
 277
 278 /*
 279  * Return current iteration position, advance internal iterator to next.
 280  * Return NULL if end of list.
 281  */
 282 struct lttng_ust_tracepoint_iter *
 283         lttng_ust_tracepoint_list_get_iter_next(struct lttng_ust_tracepoint_list *list)
 284 {
 285         struct tp_list_entry *entry;
 286
 287         if (!list->iter)
 288                 return NULL;
 289         entry = list->iter;
 290         if (entry->head.next == &list->head)
 291                 list->iter = NULL;
 292         else
 293                 list->iter = cds_list_entry(entry->head.next,
 294                                 struct tp_list_entry, head);
 295         return &entry->tp;
 296 }
 297
 298 void lttng_probes_prune_field_list(struct lttng_ust_field_list *list)
 299 {
 300         struct tp_field_list_entry *list_entry, *tmp;
 301
 302         cds_list_for_each_entry_safe(list_entry, tmp, &list->head, head) {
 303                 cds_list_del(&list_entry->head);
 304                 free(list_entry);
 305         }
 306 }
 307
 308 /*
 309  * called with UST lock held.
 310  */
 311 int lttng_probes_get_field_list(struct lttng_ust_field_list *list)
 312 {
 313         struct lttng_probe_desc *probe_desc;
 314         int i;
 315         struct cds_list_head *probe_list;
 316
 317         probe_list = lttng_get_probe_list_head();
 318         CDS_INIT_LIST_HEAD(&list->head);
 319         cds_list_for_each_entry(probe_desc, probe_list, head) {
 320                 for (i = 0; i < probe_desc->nr_events; i++) {
 321                         const struct lttng_event_desc *event_desc =
 322                                 probe_desc->event_desc[i];
 323                         int j;
 324
 325                         if (event_desc->nr_fields == 0) {
 326                                 /* Events without fields. */
 327                                 struct tp_field_list_entry *list_entry;
 328
 329                                 list_entry = zmalloc(sizeof(*list_entry));
 330                                 if (!list_entry)
 331                                         goto err_nomem;
 332                                 cds_list_add(&list_entry->head, &list->head);
 333                                 strncpy(list_entry->field.event_name,
 334                                         event_desc->name,
 335                                         LTTNG_UST_SYM_NAME_LEN);
 336                                 list_entry->field.event_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 337                                 list_entry->field.field_name[0] = '\0';
 338                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 339                                 if (!event_desc->loglevel) {
 340                                         list_entry->field.loglevel = TRACE_DEFAULT;
 341                                 } else {
 342                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 343                                 }
 344                                 list_entry->field.nowrite = 1;
 345                         }
 346
 347                         for (j = 0; j < event_desc->nr_fields; j++) {
 348                                 const struct lttng_event_field *event_field =
 349                                         &event_desc->fields[j];
 350                                 struct tp_field_list_entry *list_entry;
 351
 352                                 list_entry = zmalloc(sizeof(*list_entry));
 353                                 if (!list_entry)
 354                                         goto err_nomem;
 355                                 cds_list_add(&list_entry->head, &list->head);
 356                                 strncpy(list_entry->field.event_name,
 357                                         event_desc->name,
 358                                         LTTNG_UST_SYM_NAME_LEN);
 359                                 list_entry->field.event_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 360                                 strncpy(list_entry->field.field_name,
 361                                         event_field->name,
 362                                         LTTNG_UST_SYM_NAME_LEN);
 363                                 list_entry->field.field_name[LTTNG_UST_SYM_NAME_LEN - 1] = '\0';
 364                                 switch (event_field->type.atype) {
 365                                 case atype_integer:
 366                                         list_entry->field.type = LTTNG_UST_FIELD_INTEGER;
 367                                         break;
 368                                 case atype_string:
 369                                         list_entry->field.type = LTTNG_UST_FIELD_STRING;
 370                                         break;
 371                                 case atype_array:
 372                                         if (event_field->type.u.array.elem_type.atype != atype_integer
 373                                                 || event_field->type.u.array.elem_type.u.basic.integer.encoding == lttng_encode_none)
 374                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 375                                         else
 376                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 377                                         break;
 378                                 case atype_sequence:
 379                                         if (event_field->type.u.sequence.elem_type.atype != atype_integer
 380                                                 || event_field->type.u.sequence.elem_type.u.basic.integer.encoding == lttng_encode_none)
 381                                                 list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 382                                         else
 383                                                 list_entry->field.type = LTTNG_UST_FIELD_STRING;
 384                                         break;
 385                                 case atype_float:
 386                                         list_entry->field.type = LTTNG_UST_FIELD_FLOAT;
 387                                         break;
 388                                 case atype_enum:
 389                                         list_entry->field.type = LTTNG_UST_FIELD_ENUM;
 390                                         break;
 391                                 default:
 392                                         list_entry->field.type = LTTNG_UST_FIELD_OTHER;
 393                                 }
 394                                 if (!event_desc->loglevel) {
 395                                         list_entry->field.loglevel = TRACE_DEFAULT;
 396                                 } else {
 397                                         list_entry->field.loglevel = *(*event_desc->loglevel);
 398                                 }
 399                                 list_entry->field.nowrite = event_field->nowrite;
 400                         }
 401                 }
 402         }
 403         if (cds_list_empty(&list->head))
 404                 list->iter = NULL;
 405         else
 406                 list->iter =
 407                         cds_list_first_entry(&list->head,
 408                                 struct tp_field_list_entry, head);
 409         return 0;
 410
 411 err_nomem:
 412         lttng_probes_prune_field_list(list);
 413         return -ENOMEM;
 414 }
 415
 416 /*
 417  * Return current iteration position, advance internal iterator to next.
 418  * Return NULL if end of list.
 419  */
 420 struct lttng_ust_field_iter *
 421         lttng_ust_field_list_get_iter_next(struct lttng_ust_field_list *list)
 422 {
 423         struct tp_field_list_entry *entry;
 424
 425         if (!list->iter)
 426                 return NULL;
 427         entry = list->iter;
 428         if (entry->head.next == &list->head)
 429                 list->iter = NULL;
 430         else
 431                 list->iter = cds_list_entry(entry->head.next,
 432                                 struct tp_field_list_entry, head);
 433         return &entry->field;
 434 }