lib/dpif-linux.c

   1 /*
   2  * Copyright (c) 2008, 2009, 2010 Nicira Networks.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <config.h>
  18 #include "dpif.h"
  19
  20 #include <assert.h>
  21 #include <ctype.h>
  22 #include <errno.h>
  23 #include <fcntl.h>
  24 #include <inttypes.h>
  25 #include <net/if.h>
  26 #include <linux/ethtool.h>
  27 #include <linux/rtnetlink.h>
  28 #include <linux/sockios.h>
  29 #include <stdlib.h>
  30 #include <sys/ioctl.h>
  31 #include <unistd.h>
  32
  33 #include "dpif-provider.h"
  34 #include "ofpbuf.h"
  35 #include "poll-loop.h"
  36 #include "rtnetlink.h"
  37 #include "svec.h"
  38 #include "util.h"
  39
  40 #include "vlog.h"
  41 #define THIS_MODULE VLM_dpif_linux
  42
  43 /* Datapath interface for the openvswitch Linux kernel module. */
  44 struct dpif_linux {
  45     struct dpif dpif;
  46     int fd;
  47
  48     /* Used by dpif_linux_get_all_names(). */
  49     char *local_ifname;
  50     int minor;
  51
  52     /* Change notification. */
  53     int local_ifindex;          /* Ifindex of local port. */
  54     struct svec changed_ports;  /* Ports that have changed. */
  55     struct rtnetlink_notifier port_notifier;
  56     bool change_error;
  57 };
  58
  59 static struct vlog_rate_limit error_rl = VLOG_RATE_LIMIT_INIT(9999, 5);
  60
  61 static int do_ioctl(const struct dpif *, int cmd, const void *arg);
  62 static int lookup_minor(const char *name, int *minor);
  63 static int finish_open(struct dpif *, const char *local_ifname);
  64 static int get_openvswitch_major(void);
  65 static int create_minor(const char *name, int minor, struct dpif **dpifp);
  66 static int open_minor(int minor, struct dpif **dpifp);
  67 static int make_openvswitch_device(int minor, char **fnp);
  68 static void dpif_linux_port_changed(const struct rtnetlink_change *,
  69                                     void *dpif);
  70
  71 static struct dpif_linux *
  72 dpif_linux_cast(const struct dpif *dpif)
  73 {
  74     dpif_assert_class(dpif, &dpif_linux_class);
  75     return CONTAINER_OF(dpif, struct dpif_linux, dpif);
  76 }
  77
  78 static int
  79 dpif_linux_enumerate(struct svec *all_dps)
  80 {
  81     int major;
  82     int error;
  83     int i;
  84
  85     /* Check that the Open vSwitch module is loaded. */
  86     major = get_openvswitch_major();
  87     if (major < 0) {
  88         return -major;
  89     }
  90
  91     error = 0;
  92     for (i = 0; i < ODP_MAX; i++) {
  93         struct dpif *dpif;
  94         char devname[16];
  95         int retval;
  96
  97         sprintf(devname, "dp%d", i);
  98         retval = dpif_open(devname, "system", &dpif);
  99         if (!retval) {
 100             svec_add(all_dps, devname);
 101             dpif_uninit(dpif, true);
 102         } else if (retval != ENODEV && !error) {
 103             error = retval;
 104         }
 105     }
 106     return error;
 107 }
 108
 109 static int
 110 dpif_linux_open(const char *name, const char *type UNUSED, bool create,
 111                 struct dpif **dpifp)
 112 {
 113     int minor;
 114
 115     minor = !strncmp(name, "dp", 2)
 116             && isdigit((unsigned char)name[2]) ? atoi(name + 2) : -1;
 117     if (create) {
 118         if (minor >= 0) {
 119             return create_minor(name, minor, dpifp);
 120         } else {
 121             /* Scan for unused minor number. */
 122             for (minor = 0; minor < ODP_MAX; minor++) {
 123                 int error = create_minor(name, minor, dpifp);
 124                 if (error != EBUSY) {
 125                     return error;
 126                 }
 127             }
 128
 129             /* All datapath numbers in use. */
 130             return ENOBUFS;
 131         }
 132     } else {
 133         struct dpif_linux *dpif;
 134         struct odp_port port;
 135         int error;
 136
 137         if (minor < 0) {
 138             error = lookup_minor(name, &minor);
 139             if (error) {
 140                 return error;
 141             }
 142         }
 143
 144         error = open_minor(minor, dpifp);
 145         if (error) {
 146             return error;
 147         }
 148         dpif = dpif_linux_cast(*dpifp);
 149
 150         /* We need the local port's ifindex for the poll function.  Start by
 151          * getting the local port's name. */
 152         memset(&port, 0, sizeof port);
 153         port.port = ODPP_LOCAL;
 154         if (ioctl(dpif->fd, ODP_PORT_QUERY, &port)) {
 155             error = errno;
 156             if (error != ENODEV) {
 157                 VLOG_WARN("%s: probe returned unexpected error: %s",
 158                           dpif_name(*dpifp), strerror(error));
 159             }
 160             dpif_uninit(*dpifp, true);
 161             return error;
 162         }
 163
 164         /* Then use that to finish up opening. */
 165         return finish_open(&dpif->dpif, port.devname);
 166     }
 167 }
 168
 169 static void
 170 dpif_linux_close(struct dpif *dpif_)
 171 {
 172     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 173     rtnetlink_notifier_unregister(&dpif->port_notifier);
 174     svec_destroy(&dpif->changed_ports);
 175     free(dpif->local_ifname);
 176     close(dpif->fd);
 177     free(dpif);
 178 }
 179
 180 static int
 181 dpif_linux_get_all_names(const struct dpif *dpif_, struct svec *all_names)
 182 {
 183     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 184
 185     svec_add_nocopy(all_names, xasprintf("dp%d", dpif->minor));
 186     svec_add(all_names, dpif->local_ifname);
 187     return 0;
 188 }
 189
 190 static int
 191 dpif_linux_delete(struct dpif *dpif_)
 192 {
 193     return do_ioctl(dpif_, ODP_DP_DESTROY, NULL);
 194 }
 195
 196 static int
 197 dpif_linux_get_stats(const struct dpif *dpif_, struct odp_stats *stats)
 198 {
 199     memset(stats, 0, sizeof *stats);
 200     return do_ioctl(dpif_, ODP_DP_STATS, stats);
 201 }
 202
 203 static int
 204 dpif_linux_get_drop_frags(const struct dpif *dpif_, bool *drop_fragsp)
 205 {
 206     int drop_frags;
 207     int error;
 208
 209     error = do_ioctl(dpif_, ODP_GET_DROP_FRAGS, &drop_frags);
 210     if (!error) {
 211         *drop_fragsp = drop_frags & 1;
 212     }
 213     return error;
 214 }
 215
 216 static int
 217 dpif_linux_set_drop_frags(struct dpif *dpif_, bool drop_frags)
 218 {
 219     int drop_frags_int = drop_frags;
 220     return do_ioctl(dpif_, ODP_SET_DROP_FRAGS, &drop_frags_int);
 221 }
 222
 223 static int
 224 dpif_linux_port_add(struct dpif *dpif_, const char *devname, uint16_t flags,
 225                     uint16_t *port_no)
 226 {
 227     struct odp_port port;
 228     int error;
 229
 230     memset(&port, 0, sizeof port);
 231     strncpy(port.devname, devname, sizeof port.devname);
 232     port.flags = flags;
 233     error = do_ioctl(dpif_, ODP_PORT_ADD, &port);
 234     if (!error) {
 235         *port_no = port.port;
 236     }
 237     return error;
 238 }
 239
 240 static int
 241 dpif_linux_port_del(struct dpif *dpif_, uint16_t port_no)
 242 {
 243     int tmp = port_no;
 244     return do_ioctl(dpif_, ODP_PORT_DEL, &tmp);
 245 }
 246
 247 static int
 248 dpif_linux_port_query_by_number(const struct dpif *dpif_, uint16_t port_no,
 249                           struct odp_port *port)
 250 {
 251     memset(port, 0, sizeof *port);
 252     port->port = port_no;
 253     return do_ioctl(dpif_, ODP_PORT_QUERY, port);
 254 }
 255
 256 static int
 257 dpif_linux_port_query_by_name(const struct dpif *dpif_, const char *devname,
 258                               struct odp_port *port)
 259 {
 260     memset(port, 0, sizeof *port);
 261     strncpy(port->devname, devname, sizeof port->devname);
 262     return do_ioctl(dpif_, ODP_PORT_QUERY, port);
 263 }
 264
 265 static int
 266 dpif_linux_flow_flush(struct dpif *dpif_)
 267 {
 268     return do_ioctl(dpif_, ODP_FLOW_FLUSH, NULL);
 269 }
 270
 271 static int
 272 dpif_linux_port_list(const struct dpif *dpif_, struct odp_port *ports, int n)
 273 {
 274     struct odp_portvec pv;
 275     int error;
 276
 277     pv.ports = ports;
 278     pv.n_ports = n;
 279     error = do_ioctl(dpif_, ODP_PORT_LIST, &pv);
 280     return error ? -error : pv.n_ports;
 281 }
 282
 283 static int
 284 dpif_linux_port_poll(const struct dpif *dpif_, char **devnamep)
 285 {
 286     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 287
 288     if (dpif->change_error) {
 289         dpif->change_error = false;
 290         svec_clear(&dpif->changed_ports);
 291         return ENOBUFS;
 292     } else if (dpif->changed_ports.n) {
 293         *devnamep = dpif->changed_ports.names[--dpif->changed_ports.n];
 294         return 0;
 295     } else {
 296         return EAGAIN;
 297     }
 298 }
 299
 300 static void
 301 dpif_linux_port_poll_wait(const struct dpif *dpif_)
 302 {
 303     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 304     if (dpif->changed_ports.n || dpif->change_error) {
 305         poll_immediate_wake();
 306     } else {
 307         rtnetlink_notifier_wait();
 308     }
 309 }
 310
 311 static int
 312 dpif_linux_port_group_get(const struct dpif *dpif_, int group,
 313                           uint16_t ports[], int n)
 314 {
 315     struct odp_port_group pg;
 316     int error;
 317
 318     assert(n <= UINT16_MAX);
 319     pg.group = group;
 320     pg.ports = ports;
 321     pg.n_ports = n;
 322     error = do_ioctl(dpif_, ODP_PORT_GROUP_GET, &pg);
 323     return error ? -error : pg.n_ports;
 324 }
 325
 326 static int
 327 dpif_linux_port_group_set(struct dpif *dpif_, int group,
 328                           const uint16_t ports[], int n)
 329 {
 330     struct odp_port_group pg;
 331
 332     assert(n <= UINT16_MAX);
 333     pg.group = group;
 334     pg.ports = (uint16_t *) ports;
 335     pg.n_ports = n;
 336     return do_ioctl(dpif_, ODP_PORT_GROUP_SET, &pg);
 337 }
 338
 339 static int
 340 dpif_linux_flow_get(const struct dpif *dpif_, struct odp_flow flows[], int n)
 341 {
 342     struct odp_flowvec fv;
 343     fv.flows = flows;
 344     fv.n_flows = n;
 345     return do_ioctl(dpif_, ODP_FLOW_GET, &fv);
 346 }
 347
 348 static int
 349 dpif_linux_flow_put(struct dpif *dpif_, struct odp_flow_put *put)
 350 {
 351     return do_ioctl(dpif_, ODP_FLOW_PUT, put);
 352 }
 353
 354 static int
 355 dpif_linux_flow_del(struct dpif *dpif_, struct odp_flow *flow)
 356 {
 357     return do_ioctl(dpif_, ODP_FLOW_DEL, flow);
 358 }
 359
 360 static int
 361 dpif_linux_flow_list(const struct dpif *dpif_, struct odp_flow flows[], int n)
 362 {
 363     struct odp_flowvec fv;
 364     int error;
 365
 366     fv.flows = flows;
 367     fv.n_flows = n;
 368     error = do_ioctl(dpif_, ODP_FLOW_LIST, &fv);
 369     return error ? -error : fv.n_flows;
 370 }
 371
 372 static int
 373 dpif_linux_execute(struct dpif *dpif_, uint16_t in_port,
 374                    const union odp_action actions[], int n_actions,
 375                    const struct ofpbuf *buf)
 376 {
 377     struct odp_execute execute;
 378     memset(&execute, 0, sizeof execute);
 379     execute.in_port = in_port;
 380     execute.actions = (union odp_action *) actions;
 381     execute.n_actions = n_actions;
 382     execute.data = buf->data;
 383     execute.length = buf->size;
 384     return do_ioctl(dpif_, ODP_EXECUTE, &execute);
 385 }
 386
 387 static int
 388 dpif_linux_recv_get_mask(const struct dpif *dpif_, int *listen_mask)
 389 {
 390     return do_ioctl(dpif_, ODP_GET_LISTEN_MASK, listen_mask);
 391 }
 392
 393 static int
 394 dpif_linux_recv_set_mask(struct dpif *dpif_, int listen_mask)
 395 {
 396     return do_ioctl(dpif_, ODP_SET_LISTEN_MASK, &listen_mask);
 397 }
 398
 399 static int
 400 dpif_linux_get_sflow_probability(const struct dpif *dpif_,
 401                                  uint32_t *probability)
 402 {
 403     return do_ioctl(dpif_, ODP_GET_SFLOW_PROBABILITY, probability);
 404 }
 405
 406 static int
 407 dpif_linux_set_sflow_probability(struct dpif *dpif_, uint32_t probability)
 408 {
 409     return do_ioctl(dpif_, ODP_SET_SFLOW_PROBABILITY, &probability);
 410 }
 411
 412 static int
 413 dpif_linux_recv(struct dpif *dpif_, struct ofpbuf **bufp)
 414 {
 415     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 416     struct ofpbuf *buf;
 417     int retval;
 418     int error;
 419
 420     buf = ofpbuf_new(65536);
 421     retval = read(dpif->fd, ofpbuf_tail(buf), ofpbuf_tailroom(buf));
 422     if (retval < 0) {
 423         error = errno;
 424         if (error != EAGAIN) {
 425             VLOG_WARN_RL(&error_rl, "%s: read failed: %s",
 426                          dpif_name(dpif_), strerror(error));
 427         }
 428     } else if (retval >= sizeof(struct odp_msg)) {
 429         struct odp_msg *msg = buf->data;
 430         if (msg->length <= retval) {
 431             buf->size += retval;
 432             *bufp = buf;
 433             return 0;
 434         } else {
 435             VLOG_WARN_RL(&error_rl, "%s: discarding message truncated "
 436                          "from %"PRIu32" bytes to %d",
 437                          dpif_name(dpif_), msg->length, retval);
 438             error = ERANGE;
 439         }
 440     } else if (!retval) {
 441         VLOG_WARN_RL(&error_rl, "%s: unexpected end of file", dpif_name(dpif_));
 442         error = EPROTO;
 443     } else {
 444         VLOG_WARN_RL(&error_rl,
 445                      "%s: discarding too-short message (%d bytes)",
 446                      dpif_name(dpif_), retval);
 447         error = ERANGE;
 448     }
 449
 450     *bufp = NULL;
 451     ofpbuf_delete(buf);
 452     return error;
 453 }
 454
 455 static void
 456 dpif_linux_recv_wait(struct dpif *dpif_)
 457 {
 458     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 459     poll_fd_wait(dpif->fd, POLLIN);
 460 }
 461
 462 const struct dpif_class dpif_linux_class = {
 463     "system",
 464     NULL,
 465     NULL,
 466     dpif_linux_enumerate,
 467     dpif_linux_open,
 468     dpif_linux_close,
 469     dpif_linux_get_all_names,
 470     dpif_linux_delete,
 471     dpif_linux_get_stats,
 472     dpif_linux_get_drop_frags,
 473     dpif_linux_set_drop_frags,
 474     dpif_linux_port_add,
 475     dpif_linux_port_del,
 476     dpif_linux_port_query_by_number,
 477     dpif_linux_port_query_by_name,
 478     dpif_linux_port_list,
 479     dpif_linux_port_poll,
 480     dpif_linux_port_poll_wait,
 481     dpif_linux_port_group_get,
 482     dpif_linux_port_group_set,
 483     dpif_linux_flow_get,
 484     dpif_linux_flow_put,
 485     dpif_linux_flow_del,
 486     dpif_linux_flow_flush,
 487     dpif_linux_flow_list,
 488     dpif_linux_execute,
 489     dpif_linux_recv_get_mask,
 490     dpif_linux_recv_set_mask,
 491     dpif_linux_get_sflow_probability,
 492     dpif_linux_set_sflow_probability,
 493     dpif_linux_recv,
 494     dpif_linux_recv_wait,
 495 };
 496 \f
 497 static int get_openvswitch_major(void);
 498 static int get_major(const char *target);
 499
 500 static int
 501 do_ioctl(const struct dpif *dpif_, int cmd, const void *arg)
 502 {
 503     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 504     return ioctl(dpif->fd, cmd, arg) ? errno : 0;
 505 }
 506
 507 static int
 508 lookup_minor(const char *name, int *minorp)
 509 {
 510     struct ethtool_drvinfo drvinfo;
 511     int minor, port_no;
 512     struct ifreq ifr;
 513     int error;
 514     int sock;
 515
 516     sock = socket(AF_INET, SOCK_DGRAM, 0);
 517     if (sock < 0) {
 518         VLOG_WARN("socket(AF_INET) failed: %s", strerror(errno));
 519         error = errno;
 520         goto error;
 521     }
 522
 523     memset(&ifr, 0, sizeof ifr);
 524     strncpy(ifr.ifr_name, name, sizeof ifr.ifr_name);
 525     ifr.ifr_data = (caddr_t) &drvinfo;
 526
 527     memset(&drvinfo, 0, sizeof drvinfo);
 528     drvinfo.cmd = ETHTOOL_GDRVINFO;
 529     if (ioctl(sock, SIOCETHTOOL, &ifr)) {
 530         VLOG_WARN("ioctl(SIOCETHTOOL) failed: %s", strerror(errno));
 531         error = errno;
 532         goto error_close_sock;
 533     }
 534
 535     if (strcmp(drvinfo.driver, "openvswitch")) {
 536         VLOG_WARN("%s is not an openvswitch device", name);
 537         error = EOPNOTSUPP;
 538         goto error_close_sock;
 539     }
 540
 541     if (sscanf(drvinfo.bus_info, "%d.%d", &minor, &port_no) != 2) {
 542         VLOG_WARN("%s ethtool bus_info has unexpected format", name);
 543         error = EPROTOTYPE;
 544         goto error_close_sock;
 545     } else if (port_no != ODPP_LOCAL) {
 546         /* This is an Open vSwitch device but not the local port.  We
 547          * intentionally support only using the name of the local port as the
 548          * name of a datapath; otherwise, it would be too difficult to
 549          * enumerate all the names of a datapath. */
 550         error = EOPNOTSUPP;
 551         goto error_close_sock;
 552     }
 553
 554     *minorp = minor;
 555     close(sock);
 556     return 0;
 557
 558 error_close_sock:
 559     close(sock);
 560 error:
 561     return error;
 562 }
 563
 564 static int
 565 make_openvswitch_device(int minor, char **fnp)
 566 {
 567     const char dirname[] = "/dev/net";
 568     int major;
 569     dev_t dev;
 570     struct stat s;
 571     char fn[128];
 572
 573     *fnp = NULL;
 574
 575     major = get_openvswitch_major();
 576     if (major < 0) {
 577         return -major;
 578     }
 579     dev = makedev(major, minor);
 580
 581     sprintf(fn, "%s/dp%d", dirname, minor);
 582     if (!stat(fn, &s)) {
 583         if (!S_ISCHR(s.st_mode)) {
 584             VLOG_WARN_RL(&error_rl, "%s is not a character device, fixing",
 585                          fn);
 586         } else if (s.st_rdev != dev) {
 587             VLOG_WARN_RL(&error_rl,
 588                          "%s is device %u:%u but should be %u:%u, fixing",
 589                          fn, major(s.st_rdev), minor(s.st_rdev),
 590                          major(dev), minor(dev));
 591         } else {
 592             goto success;
 593         }
 594         if (unlink(fn)) {
 595             VLOG_WARN_RL(&error_rl, "%s: unlink failed (%s)",
 596                          fn, strerror(errno));
 597             return errno;
 598         }
 599     } else if (errno == ENOENT) {
 600         if (stat(dirname, &s)) {
 601             if (errno == ENOENT) {
 602                 if (mkdir(dirname, 0755)) {
 603                     VLOG_WARN_RL(&error_rl, "%s: mkdir failed (%s)",
 604                                  dirname, strerror(errno));
 605                     return errno;
 606                 }
 607             } else {
 608                 VLOG_WARN_RL(&error_rl, "%s: stat failed (%s)",
 609                              dirname, strerror(errno));
 610                 return errno;
 611             }
 612         }
 613     } else {
 614         VLOG_WARN_RL(&error_rl, "%s: stat failed (%s)", fn, strerror(errno));
 615         return errno;
 616     }
 617
 618     /* The device needs to be created. */
 619     if (mknod(fn, S_IFCHR | 0700, dev)) {
 620         VLOG_WARN_RL(&error_rl,
 621                      "%s: creating character device %u:%u failed (%s)",
 622                      fn, major(dev), minor(dev), strerror(errno));
 623         return errno;
 624     }
 625
 626 success:
 627     *fnp = xstrdup(fn);
 628     return 0;
 629 }
 630
 631 /* Return the major device number of the Open vSwitch device.  If it
 632  * cannot be determined, a negative errno is returned. */
 633 static int
 634 get_openvswitch_major(void)
 635 {
 636     static int openvswitch_major = -1;
 637     if (openvswitch_major < 0) {
 638         openvswitch_major = get_major("openvswitch");
 639     }
 640     return openvswitch_major;
 641 }
 642
 643 static int
 644 get_major(const char *target)
 645 {
 646     const char fn[] = "/proc/devices";
 647     char line[128];
 648     FILE *file;
 649     int ln;
 650
 651     file = fopen(fn, "r");
 652     if (!file) {
 653         VLOG_ERR("opening %s failed (%s)", fn, strerror(errno));
 654         return -errno;
 655     }
 656
 657     for (ln = 1; fgets(line, sizeof line, file); ln++) {
 658         char name[64];
 659         int major;
 660
 661         if (!strncmp(line, "Character", 9) || line[0] == '\0') {
 662             /* Nothing to do. */
 663         } else if (!strncmp(line, "Block", 5)) {
 664             /* We only want character devices, so skip the rest of the file. */
 665             break;
 666         } else if (sscanf(line, "%d %63s", &major, name)) {
 667             if (!strcmp(name, target)) {
 668                 fclose(file);
 669                 return major;
 670             }
 671         } else {
 672             static bool warned;
 673             if (!warned) {
 674                 VLOG_WARN("%s:%d: syntax error", fn, ln);
 675             }
 676             warned = true;
 677         }
 678     }
 679
 680     VLOG_ERR("%s: %s major not found (is the module loaded?)", fn, target);
 681     return -ENODEV;
 682 }
 683
 684 static int
 685 finish_open(struct dpif *dpif_, const char *local_ifname)
 686 {
 687     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 688     dpif->local_ifname = xstrdup(local_ifname);
 689     dpif->local_ifindex = if_nametoindex(local_ifname);
 690     if (!dpif->local_ifindex) {
 691         int error = errno;
 692         dpif_uninit(dpif_, true);
 693         VLOG_WARN("could not get ifindex of %s device: %s",
 694                   local_ifname, strerror(errno));
 695         return error;
 696     }
 697     return 0;
 698 }
 699
 700 static int
 701 create_minor(const char *name, int minor, struct dpif **dpifp)
 702 {
 703     int error = open_minor(minor, dpifp);
 704     if (!error) {
 705         error = do_ioctl(*dpifp, ODP_DP_CREATE, name);
 706         if (!error) {
 707             error = finish_open(*dpifp, name);
 708         } else {
 709             dpif_uninit(*dpifp, true);
 710         }
 711     }
 712     return error;
 713 }
 714
 715 static int
 716 open_minor(int minor, struct dpif **dpifp)
 717 {
 718     int error;
 719     char *fn;
 720     int fd;
 721
 722     error = make_openvswitch_device(minor, &fn);
 723     if (error) {
 724         return error;
 725     }
 726
 727     fd = open(fn, O_RDONLY | O_NONBLOCK);
 728     if (fd >= 0) {
 729         struct dpif_linux *dpif = xmalloc(sizeof *dpif);
 730         error = rtnetlink_notifier_register(&dpif->port_notifier,
 731                                            dpif_linux_port_changed, dpif);
 732         if (!error) {
 733             char *name;
 734
 735             name = xasprintf("dp%d", minor);
 736             dpif_init(&dpif->dpif, &dpif_linux_class, name, minor, minor);
 737             free(name);
 738
 739             dpif->fd = fd;
 740             dpif->local_ifname = NULL;
 741             dpif->minor = minor;
 742             dpif->local_ifindex = 0;
 743             svec_init(&dpif->changed_ports);
 744             dpif->change_error = false;
 745             *dpifp = &dpif->dpif;
 746         } else {
 747             free(dpif);
 748         }
 749     } else {
 750         error = errno;
 751         VLOG_WARN("%s: open failed (%s)", fn, strerror(error));
 752     }
 753     free(fn);
 754
 755     return error;
 756 }
 757
 758 static void
 759 dpif_linux_port_changed(const struct rtnetlink_change *change, void *dpif_)
 760 {
 761     struct dpif_linux *dpif = dpif_;
 762
 763     if (change) {
 764         if (change->master_ifindex == dpif->local_ifindex
 765             && (change->nlmsg_type == RTM_NEWLINK
 766                 || change->nlmsg_type == RTM_DELLINK))
 767         {
 768             /* Our datapath changed, either adding a new port or deleting an
 769              * existing one. */
 770             if (!svec_contains(&dpif->changed_ports, change->ifname)) {
 771                 svec_add(&dpif->changed_ports, change->ifname);
 772                 svec_sort(&dpif->changed_ports);
 773             }
 774         }
 775     } else {
 776         dpif->change_error = true;
 777     }
 778 }