bgpd/bgp_labelpool.c

   1 /*
   2  * BGP Label Pool - Manage label chunk allocations from zebra asynchronously
   3  *
   4  * Copyright (C) 2018 LabN Consulting, L.L.C.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the Free
   8  * Software Foundation; either version 2 of the License, or (at your option)
   9  * any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14  * more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; see the file COPYING; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 #include <zebra.h>
  22
  23 #include "log.h"
  24 #include "memory.h"
  25 #include "stream.h"
  26 #include "mpls.h"
  27 #include "vty.h"
  28 #include "linklist.h"
  29 #include "skiplist.h"
  30 #include "workqueue.h"
  31 #include "zclient.h"
  32 #include "mpls.h"
  33
  34 #include "bgpd/bgpd.h"
  35 #include "bgpd/bgp_labelpool.h"
  36 #include "bgpd/bgp_debug.h"
  37 #include "bgpd/bgp_errors.h"
  38 #include "bgpd/bgp_route.h"
  39
  40 /*
  41  * Definitions and external declarations.
  42  */
  43 extern struct zclient *zclient;
  44
  45 /*
  46  * Remember where pool data are kept
  47  */
  48 static struct labelpool *lp;
  49
  50 /* request this many labels at a time from zebra */
  51 #define LP_CHUNK_SIZE   50
  52
  53 DEFINE_MTYPE_STATIC(BGPD, BGP_LABEL_CHUNK, "BGP Label Chunk")
  54 DEFINE_MTYPE_STATIC(BGPD, BGP_LABEL_FIFO, "BGP Label FIFO item")
  55 DEFINE_MTYPE_STATIC(BGPD, BGP_LABEL_CB, "BGP Dynamic Label Assignment")
  56 DEFINE_MTYPE_STATIC(BGPD, BGP_LABEL_CBQ, "BGP Dynamic Label Callback")
  57
  58 struct lp_chunk {
  59         uint32_t        first;
  60         uint32_t        last;
  61 };
  62
  63 /*
  64  * label control block
  65  */
  66 struct lp_lcb {
  67         mpls_label_t    label;          /* MPLS_LABEL_NONE = not allocated */
  68         int             type;
  69         void            *labelid;       /* unique ID */
  70         /*
  71          * callback for label allocation and loss
  72          *
  73          * allocated: false = lost
  74          */
  75         int             (*cbfunc)(mpls_label_t label, void *lblid, bool alloc);
  76 };
  77
  78 struct lp_fifo {
  79         struct lp_fifo_item fifo;
  80         struct lp_lcb   lcb;
  81 };
  82
  83 DECLARE_LIST(lp_fifo, struct lp_fifo, fifo)
  84
  85 struct lp_cbq_item {
  86         int             (*cbfunc)(mpls_label_t label, void *lblid, bool alloc);
  87         int             type;
  88         mpls_label_t    label;
  89         void            *labelid;
  90         bool            allocated;      /* false = lost */
  91 };
  92
  93 static wq_item_status lp_cbq_docallback(struct work_queue *wq, void *data)
  94 {
  95         struct lp_cbq_item *lcbq = data;
  96         int rc;
  97         int debug = BGP_DEBUG(labelpool, LABELPOOL);
  98
  99         if (debug)
 100                 zlog_debug("%s: calling callback with labelid=%p label=%u allocated=%d",
 101                         __func__, lcbq->labelid, lcbq->label, lcbq->allocated);
 102
 103         if (lcbq->label == MPLS_LABEL_NONE) {
 104                 /* shouldn't happen */
 105                 flog_err(EC_BGP_LABEL, "%s: error: label==MPLS_LABEL_NONE",
 106                          __func__);
 107                 return WQ_SUCCESS;
 108         }
 109
 110         rc = (*(lcbq->cbfunc))(lcbq->label, lcbq->labelid, lcbq->allocated);
 111
 112         if (lcbq->allocated && rc) {
 113                 /*
 114                  * Callback rejected allocation. This situation could arise
 115                  * if there was a label request followed by the requestor
 116                  * deciding it didn't need the assignment (e.g., config
 117                  * change) while the reply to the original request (with
 118                  * label) was in the work queue.
 119                  */
 120                 if (debug)
 121                         zlog_debug("%s: callback rejected allocation, releasing labelid=%p label=%u",
 122                                 __func__, lcbq->labelid, lcbq->label);
 123
 124                 uintptr_t lbl = lcbq->label;
 125                 void *labelid;
 126                 struct lp_lcb *lcb;
 127
 128                 /*
 129                  * If the rejected label was marked inuse by this labelid,
 130                  * release the label back to the pool.
 131                  *
 132                  * Further, if the rejected label was still assigned to
 133                  * this labelid in the LCB, delete the LCB.
 134                  */
 135                 if (!skiplist_search(lp->inuse, (void *)lbl, &labelid)) {
 136                         if (labelid == lcbq->labelid) {
 137                                 if (!skiplist_search(lp->ledger, labelid,
 138                                         (void **)&lcb)) {
 139                                         if (lcbq->label == lcb->label)
 140                                                 skiplist_delete(lp->ledger,
 141                                                         labelid, NULL);
 142                                 }
 143                                 skiplist_delete(lp->inuse, (void *)lbl, NULL);
 144                         }
 145                 }
 146         }
 147
 148         return WQ_SUCCESS;
 149 }
 150
 151 static void lp_cbq_item_free(struct work_queue *wq, void *data)
 152 {
 153         XFREE(MTYPE_BGP_LABEL_CBQ, data);
 154 }
 155
 156 static void lp_lcb_free(void *goner)
 157 {
 158         XFREE(MTYPE_BGP_LABEL_CB, goner);
 159 }
 160
 161 static void lp_chunk_free(void *goner)
 162 {
 163         XFREE(MTYPE_BGP_LABEL_CHUNK, goner);
 164 }
 165
 166 void bgp_lp_init(struct thread_master *master, struct labelpool *pool)
 167 {
 168         if (BGP_DEBUG(labelpool, LABELPOOL))
 169                 zlog_debug("%s: entry", __func__);
 170
 171         lp = pool;      /* Set module pointer to pool data */
 172
 173         lp->ledger = skiplist_new(0, NULL, lp_lcb_free);
 174         lp->inuse = skiplist_new(0, NULL, NULL);
 175         lp->chunks = list_new();
 176         lp->chunks->del = lp_chunk_free;
 177         lp_fifo_init(&lp->requests);
 178         lp->callback_q = work_queue_new(master, "label callbacks");
 179
 180         lp->callback_q->spec.workfunc = lp_cbq_docallback;
 181         lp->callback_q->spec.del_item_data = lp_cbq_item_free;
 182         lp->callback_q->spec.max_retries = 0;
 183 }
 184
 185 /* check if a label callback was for a BGP LU path, and if so, unlock it */
 186 static void check_bgp_lu_cb_unlock(struct lp_lcb *lcb)
 187 {
 188         if (lcb->type == LP_TYPE_BGP_LU)
 189                 bgp_path_info_unlock(lcb->labelid);
 190 }
 191
 192 /* check if a label callback was for a BGP LU path, and if so, lock it */
 193 static void check_bgp_lu_cb_lock(struct lp_lcb *lcb)
 194 {
 195         if (lcb->type == LP_TYPE_BGP_LU)
 196                 bgp_path_info_lock(lcb->labelid);
 197 }
 198
 199 void bgp_lp_finish(void)
 200 {
 201         struct lp_fifo *lf;
 202         struct work_queue_item *item, *titem;
 203
 204         if (!lp)
 205                 return;
 206
 207         skiplist_free(lp->ledger);
 208         lp->ledger = NULL;
 209
 210         skiplist_free(lp->inuse);
 211         lp->inuse = NULL;
 212
 213         list_delete(&lp->chunks);
 214
 215         while ((lf = lp_fifo_pop(&lp->requests))) {
 216                 check_bgp_lu_cb_unlock(&lf->lcb);
 217                 XFREE(MTYPE_BGP_LABEL_FIFO, lf);
 218         }
 219         lp_fifo_fini(&lp->requests);
 220
 221         /* we must unlock path infos for LU callbacks; but we cannot do that
 222          * in the deletion callback of the workqueue, as that is also called
 223          * to remove an element from the queue after it has been run, resulting
 224          * in a double unlock. Hence we need to iterate over our queues and
 225          * lists and manually perform the unlocking (ugh)
 226          */
 227         STAILQ_FOREACH_SAFE (item, &lp->callback_q->items, wq, titem)
 228                 check_bgp_lu_cb_unlock(item->data);
 229
 230         work_queue_free_and_null(&lp->callback_q);
 231
 232         lp = NULL;
 233 }
 234
 235 static mpls_label_t get_label_from_pool(void *labelid)
 236 {
 237         struct listnode *node;
 238         struct lp_chunk *chunk;
 239         int debug = BGP_DEBUG(labelpool, LABELPOOL);
 240
 241         /*
 242          * Find a free label
 243          * Linear search is not efficient but should be executed infrequently.
 244          */
 245         for (ALL_LIST_ELEMENTS_RO(lp->chunks, node, chunk)) {
 246                 uintptr_t lbl;
 247
 248                 if (debug)
 249                         zlog_debug("%s: chunk first=%u last=%u",
 250                                 __func__, chunk->first, chunk->last);
 251
 252                 for (lbl = chunk->first; lbl <= chunk->last; ++lbl) {
 253                         /* labelid is key to all-request "ledger" list */
 254                         if (!skiplist_insert(lp->inuse, (void *)lbl, labelid)) {
 255                                 /*
 256                                  * Success
 257                                  */
 258                                 return lbl;
 259                         }
 260                 }
 261         }
 262         return MPLS_LABEL_NONE;
 263 }
 264
 265 /*
 266  * Success indicated by value of "label" field in returned LCB
 267  */
 268 static struct lp_lcb *lcb_alloc(
 269         int     type,
 270         void    *labelid,
 271         int     (*cbfunc)(mpls_label_t label, void *labelid, bool allocated))
 272 {
 273         /*
 274          * Set up label control block
 275          */
 276         struct lp_lcb *new = XCALLOC(MTYPE_BGP_LABEL_CB,
 277                 sizeof(struct lp_lcb));
 278
 279         new->label = get_label_from_pool(labelid);
 280         new->type = type;
 281         new->labelid = labelid;
 282         new->cbfunc = cbfunc;
 283
 284         return new;
 285 }
 286
 287 /*
 288  * Callers who need labels must supply a type, labelid, and callback.
 289  * The type is a value defined in bgp_labelpool.h (add types as needed).
 290  * The callback is for asynchronous notification of label allocation.
 291  * The labelid is passed as an argument to the callback. It should be unique
 292  * to the requested label instance.
 293  *
 294  * If zebra is not connected, callbacks with labels will be delayed
 295  * until connection is established. If zebra connection is lost after
 296  * labels have been assigned, existing assignments via this labelpool
 297  * module will continue until reconnection.
 298  *
 299  * When connection to zebra is reestablished, previous label assignments
 300  * will be invalidated (via callbacks having the "allocated" parameter unset)
 301  * and new labels will be automatically reassigned by this labelpool module
 302  * (that is, a requestor does not need to call lp_get() again if it is
 303  * notified via callback that its label has been lost: it will eventually
 304  * get another callback with a new label assignment).
 305  *
 306  * Prior requests for a given labelid are detected so that requests and
 307  * assignments are not duplicated.
 308  */
 309 void bgp_lp_get(
 310         int     type,
 311         void    *labelid,
 312         int     (*cbfunc)(mpls_label_t label, void *labelid, bool allocated))
 313 {
 314         struct lp_lcb *lcb;
 315         int requested = 0;
 316         int debug = BGP_DEBUG(labelpool, LABELPOOL);
 317
 318         if (debug)
 319                 zlog_debug("%s: labelid=%p", __func__, labelid);
 320
 321         /*
 322          * Have we seen this request before?
 323          */
 324         if (!skiplist_search(lp->ledger, labelid, (void **)&lcb)) {
 325                 requested = 1;
 326         } else {
 327                 lcb = lcb_alloc(type, labelid, cbfunc);
 328                 if (debug)
 329                         zlog_debug("%s: inserting lcb=%p label=%u",
 330                                 __func__, lcb, lcb->label);
 331                 int rc = skiplist_insert(lp->ledger, labelid, lcb);
 332
 333                 if (rc) {
 334                         /* shouldn't happen */
 335                         flog_err(EC_BGP_LABEL,
 336                                  "%s: can't insert new LCB into ledger list",
 337                                  __func__);
 338                         XFREE(MTYPE_BGP_LABEL_CB, lcb);
 339                         return;
 340                 }
 341         }
 342
 343         if (lcb->label != MPLS_LABEL_NONE) {
 344                 /*
 345                  * Fast path: we filled the request from local pool (or
 346                  * this is a duplicate request that we filled already).
 347                  * Enqueue response work item with new label.
 348                  */
 349                 struct lp_cbq_item *q;
 350
 351                 q = XCALLOC(MTYPE_BGP_LABEL_CBQ, sizeof(struct lp_cbq_item));
 352
 353                 q->cbfunc = lcb->cbfunc;
 354                 q->type = lcb->type;
 355                 q->label = lcb->label;
 356                 q->labelid = lcb->labelid;
 357                 q->allocated = true;
 358
 359                 /* if this is a LU request, lock path info before queueing */
 360                 check_bgp_lu_cb_lock(lcb);
 361
 362                 work_queue_add(lp->callback_q, q);
 363
 364                 return;
 365         }
 366
 367         if (requested)
 368                 return;
 369
 370         if (debug)
 371                 zlog_debug("%s: slow path. lcb=%p label=%u",
 372                         __func__, lcb, lcb->label);
 373
 374         /*
 375          * Slow path: we are out of labels in the local pool,
 376          * so remember the request and also get another chunk from
 377          * the label manager.
 378          *
 379          * We track number of outstanding label requests: don't
 380          * need to get a chunk for each one.
 381          */
 382
 383         struct lp_fifo *lf = XCALLOC(MTYPE_BGP_LABEL_FIFO,
 384                 sizeof(struct lp_fifo));
 385
 386         lf->lcb = *lcb;
 387         /* if this is a LU request, lock path info before queueing */
 388         check_bgp_lu_cb_lock(lcb);
 389
 390         lp_fifo_add_tail(&lp->requests, lf);
 391
 392         if (lp_fifo_count(&lp->requests) > lp->pending_count) {
 393                 if (!zclient || zclient->sock < 0)
 394                         return;
 395                 if (!zclient_send_get_label_chunk(zclient, 0, LP_CHUNK_SIZE,
 396                                                   MPLS_LABEL_BASE_ANY))
 397                         lp->pending_count += LP_CHUNK_SIZE;
 398         }
 399 }
 400
 401 void bgp_lp_release(
 402         int             type,
 403         void            *labelid,
 404         mpls_label_t    label)
 405 {
 406         struct lp_lcb *lcb;
 407
 408         if (!skiplist_search(lp->ledger, labelid, (void **)&lcb)) {
 409                 if (label == lcb->label && type == lcb->type) {
 410                         uintptr_t lbl = label;
 411
 412                         /* no longer in use */
 413                         skiplist_delete(lp->inuse, (void *)lbl, NULL);
 414
 415                         /* no longer requested */
 416                         skiplist_delete(lp->ledger, labelid, NULL);
 417                 }
 418         }
 419 }
 420
 421 /*
 422  * zebra response giving us a chunk of labels
 423  */
 424 void bgp_lp_event_chunk(uint8_t keep, uint32_t first, uint32_t last)
 425 {
 426         struct lp_chunk *chunk;
 427         int debug = BGP_DEBUG(labelpool, LABELPOOL);
 428         struct lp_fifo *lf;
 429
 430         if (last < first) {
 431                 flog_err(EC_BGP_LABEL,
 432                          "%s: zebra label chunk invalid: first=%u, last=%u",
 433                          __func__, first, last);
 434                 return;
 435         }
 436
 437         chunk = XCALLOC(MTYPE_BGP_LABEL_CHUNK, sizeof(struct lp_chunk));
 438
 439         chunk->first = first;
 440         chunk->last = last;
 441
 442         listnode_add(lp->chunks, chunk);
 443
 444         lp->pending_count -= (last - first + 1);
 445
 446         if (debug) {
 447                 zlog_debug("%s: %zu pending requests", __func__,
 448                         lp_fifo_count(&lp->requests));
 449         }
 450
 451         while ((lf = lp_fifo_first(&lp->requests))) {
 452
 453                 struct lp_lcb *lcb;
 454                 void *labelid = lf->lcb.labelid;
 455
 456                 if (skiplist_search(lp->ledger, labelid, (void **)&lcb)) {
 457                         /* request no longer in effect */
 458
 459                         if (debug) {
 460                                 zlog_debug("%s: labelid %p: request no longer in effect",
 461                                                 __func__, labelid);
 462                         }
 463                         goto finishedrequest;
 464                 }
 465
 466                 /* have LCB */
 467                 if (lcb->label != MPLS_LABEL_NONE) {
 468                         /* request already has a label */
 469                         if (debug) {
 470                                 zlog_debug("%s: labelid %p: request already has a label: %u=0x%x, lcb=%p",
 471                                                 __func__, labelid,
 472                                                 lcb->label, lcb->label, lcb);
 473                         }
 474                         /* if this was a BGP_LU request, unlock path info node
 475                          */
 476                         check_bgp_lu_cb_unlock(lcb);
 477
 478                         goto finishedrequest;
 479                 }
 480
 481                 lcb->label = get_label_from_pool(lcb->labelid);
 482
 483                 if (lcb->label == MPLS_LABEL_NONE) {
 484                         /*
 485                          * Out of labels in local pool, await next chunk
 486                          */
 487                         if (debug) {
 488                                 zlog_debug("%s: out of labels, await more",
 489                                                 __func__);
 490                         }
 491                         break;
 492                 }
 493
 494                 /*
 495                  * we filled the request from local pool.
 496                  * Enqueue response work item with new label.
 497                  */
 498                 struct lp_cbq_item *q = XCALLOC(MTYPE_BGP_LABEL_CBQ,
 499                         sizeof(struct lp_cbq_item));
 500
 501                 q->cbfunc = lcb->cbfunc;
 502                 q->type = lcb->type;
 503                 q->label = lcb->label;
 504                 q->labelid = lcb->labelid;
 505                 q->allocated = true;
 506
 507                 if (debug)
 508                         zlog_debug("%s: assigning label %u to labelid %p",
 509                                 __func__, q->label, q->labelid);
 510
 511                 work_queue_add(lp->callback_q, q);
 512
 513 finishedrequest:
 514                 lp_fifo_del(&lp->requests, lf);
 515                 XFREE(MTYPE_BGP_LABEL_FIFO, lf);
 516         }
 517 }
 518
 519 /*
 520  * continue using allocated labels until zebra returns
 521  */
 522 void bgp_lp_event_zebra_down(void)
 523 {
 524         /* rats. */
 525 }
 526
 527 /*
 528  * Inform owners of previously-allocated labels that their labels
 529  * are not valid. Request chunk from zebra large enough to satisfy
 530  * previously-allocated labels plus any outstanding requests.
 531  */
 532 void bgp_lp_event_zebra_up(void)
 533 {
 534         int labels_needed;
 535         int chunks_needed;
 536         void *labelid;
 537         struct lp_lcb *lcb;
 538         int lm_init_ok;
 539
 540         /*
 541          * Get label chunk allocation request dispatched to zebra
 542          */
 543         labels_needed = lp_fifo_count(&lp->requests) +
 544                 skiplist_count(lp->inuse);
 545
 546         /* round up */
 547         chunks_needed = (labels_needed / LP_CHUNK_SIZE) + 1;
 548         labels_needed = chunks_needed * LP_CHUNK_SIZE;
 549
 550         lm_init_ok = lm_label_manager_connect(zclient, 1) == 0;
 551
 552         if (!lm_init_ok) {
 553                 zlog_err("%s: label manager connection error", __func__);
 554                 return;
 555         }
 556
 557         zclient_send_get_label_chunk(zclient, 0, labels_needed,
 558                                      MPLS_LABEL_BASE_ANY);
 559         lp->pending_count = labels_needed;
 560
 561         /*
 562          * Invalidate current list of chunks
 563          */
 564         list_delete_all_node(lp->chunks);
 565
 566         /*
 567          * Invalidate any existing labels and requeue them as requests
 568          */
 569         while (!skiplist_first(lp->inuse, NULL, &labelid)) {
 570
 571                 /*
 572                  * Get LCB
 573                  */
 574                 if (!skiplist_search(lp->ledger, labelid, (void **)&lcb)) {
 575
 576                         if (lcb->label != MPLS_LABEL_NONE) {
 577                                 /*
 578                                  * invalidate
 579                                  */
 580                                 struct lp_cbq_item *q;
 581
 582                                 q = XCALLOC(MTYPE_BGP_LABEL_CBQ,
 583                                         sizeof(struct lp_cbq_item));
 584                                 q->cbfunc = lcb->cbfunc;
 585                                 q->type = lcb->type;
 586                                 q->label = lcb->label;
 587                                 q->labelid = lcb->labelid;
 588                                 q->allocated = false;
 589                                 check_bgp_lu_cb_lock(lcb);
 590                                 work_queue_add(lp->callback_q, q);
 591
 592                                 lcb->label = MPLS_LABEL_NONE;
 593                         }
 594
 595                         /*
 596                          * request queue
 597                          */
 598                         struct lp_fifo *lf = XCALLOC(MTYPE_BGP_LABEL_FIFO,
 599                                 sizeof(struct lp_fifo));
 600
 601                         lf->lcb = *lcb;
 602                         check_bgp_lu_cb_lock(lcb);
 603                         lp_fifo_add_tail(&lp->requests, lf);
 604                 }
 605
 606                 skiplist_delete_first(lp->inuse);
 607         }
 608 }