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 "netdev.h"
  35 #include "ofpbuf.h"
  36 #include "poll-loop.h"
  37 #include "rtnetlink.h"
  38 #include "svec.h"
  39 #include "util.h"
  40
  41 #include "vlog.h"
  42 #define THIS_MODULE VLM_dpif_linux
  43
  44 /* Datapath interface for the openvswitch Linux kernel module. */
  45 struct dpif_linux {
  46     struct dpif dpif;
  47     int fd;
  48
  49     /* Used by dpif_linux_get_all_names(). */
  50     char *local_ifname;
  51     int minor;
  52
  53     /* Change notification. */
  54     int local_ifindex;          /* Ifindex of local port. */
  55     struct svec changed_ports;  /* Ports that have changed. */
  56     struct rtnetlink_notifier port_notifier;
  57     bool change_error;
  58 };
  59
  60 static struct vlog_rate_limit error_rl = VLOG_RATE_LIMIT_INIT(9999, 5);
  61
  62 static int do_ioctl(const struct dpif *, int cmd, const void *arg);
  63 static int lookup_minor(const char *name, int *minor);
  64 static int finish_open(struct dpif *, const char *local_ifname);
  65 static int get_openvswitch_major(void);
  66 static int create_minor(const char *name, int minor, struct dpif **dpifp);
  67 static int open_minor(int minor, struct dpif **dpifp);
  68 static int make_openvswitch_device(int minor, char **fnp);
  69 static void dpif_linux_port_changed(const struct rtnetlink_change *,
  70                                     void *dpif);
  71
  72 static struct dpif_linux *
  73 dpif_linux_cast(const struct dpif *dpif)
  74 {
  75     dpif_assert_class(dpif, &dpif_linux_class);
  76     return CONTAINER_OF(dpif, struct dpif_linux, dpif);
  77 }
  78
  79 static int
  80 dpif_linux_enumerate(struct svec *all_dps)
  81 {
  82     int major;
  83     int error;
  84     int i;
  85
  86     /* Check that the Open vSwitch module is loaded. */
  87     major = get_openvswitch_major();
  88     if (major < 0) {
  89         return -major;
  90     }
  91
  92     error = 0;
  93     for (i = 0; i < ODP_MAX; i++) {
  94         struct dpif *dpif;
  95         char devname[16];
  96         int retval;
  97
  98         sprintf(devname, "dp%d", i);
  99         retval = dpif_open(devname, "system", &dpif);
 100         if (!retval) {
 101             svec_add(all_dps, devname);
 102             dpif_uninit(dpif, true);
 103         } else if (retval != ENODEV && !error) {
 104             error = retval;
 105         }
 106     }
 107     return error;
 108 }
 109
 110 static int
 111 dpif_linux_open(const char *name, const char *type OVS_UNUSED, bool create,
 112                 struct dpif **dpifp)
 113 {
 114     int minor;
 115
 116     minor = !strncmp(name, "dp", 2)
 117             && isdigit((unsigned char)name[2]) ? atoi(name + 2) : -1;
 118     if (create) {
 119         if (minor >= 0) {
 120             return create_minor(name, minor, dpifp);
 121         } else {
 122             /* Scan for unused minor number. */
 123             for (minor = 0; minor < ODP_MAX; minor++) {
 124                 int error = create_minor(name, minor, dpifp);
 125                 if (error != EBUSY) {
 126                     return error;
 127                 }
 128             }
 129
 130             /* All datapath numbers in use. */
 131             return ENOBUFS;
 132         }
 133     } else {
 134         struct dpif_linux *dpif;
 135         struct odp_port port;
 136         int error;
 137
 138         if (minor < 0) {
 139             error = lookup_minor(name, &minor);
 140             if (error) {
 141                 return error;
 142             }
 143         }
 144
 145         error = open_minor(minor, dpifp);
 146         if (error) {
 147             return error;
 148         }
 149         dpif = dpif_linux_cast(*dpifp);
 150
 151         /* We need the local port's ifindex for the poll function.  Start by
 152          * getting the local port's name. */
 153         memset(&port, 0, sizeof port);
 154         port.port = ODPP_LOCAL;
 155         if (ioctl(dpif->fd, ODP_PORT_QUERY, &port)) {
 156             error = errno;
 157             if (error != ENODEV) {
 158                 VLOG_WARN("%s: probe returned unexpected error: %s",
 159                           dpif_name(*dpifp), strerror(error));
 160             }
 161             dpif_uninit(*dpifp, true);
 162             return error;
 163         }
 164
 165         /* Then use that to finish up opening. */
 166         return finish_open(&dpif->dpif, port.devname);
 167     }
 168 }
 169
 170 static void
 171 dpif_linux_close(struct dpif *dpif_)
 172 {
 173     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 174     rtnetlink_notifier_unregister(&dpif->port_notifier);
 175     svec_destroy(&dpif->changed_ports);
 176     free(dpif->local_ifname);
 177     close(dpif->fd);
 178     free(dpif);
 179 }
 180
 181 static int
 182 dpif_linux_get_all_names(const struct dpif *dpif_, struct svec *all_names)
 183 {
 184     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 185
 186     svec_add_nocopy(all_names, xasprintf("dp%d", dpif->minor));
 187     svec_add(all_names, dpif->local_ifname);
 188     return 0;
 189 }
 190
 191 static int
 192 dpif_linux_destroy(struct dpif *dpif_)
 193 {
 194     struct odp_port *ports;
 195     size_t n_ports;
 196     int err;
 197     int i;
 198
 199     err = dpif_port_list(dpif_, &ports, &n_ports);
 200     if (err) {
 201         return err;
 202     }
 203
 204     for (i = 0; i < n_ports; i++) {
 205         if (ports[i].port != ODPP_LOCAL) {
 206             err = do_ioctl(dpif_, ODP_VPORT_DEL, ports[i].devname);
 207             if (err) {
 208                 VLOG_WARN_RL(&error_rl, "%s: error deleting port %s (%s)",
 209                              dpif_name(dpif_), ports[i].devname, strerror(err));
 210             }
 211         }
 212     }
 213
 214     free(ports);
 215
 216     return do_ioctl(dpif_, ODP_DP_DESTROY, NULL);
 217 }
 218
 219 static int
 220 dpif_linux_get_stats(const struct dpif *dpif_, struct odp_stats *stats)
 221 {
 222     memset(stats, 0, sizeof *stats);
 223     return do_ioctl(dpif_, ODP_DP_STATS, stats);
 224 }
 225
 226 static int
 227 dpif_linux_get_drop_frags(const struct dpif *dpif_, bool *drop_fragsp)
 228 {
 229     int drop_frags;
 230     int error;
 231
 232     error = do_ioctl(dpif_, ODP_GET_DROP_FRAGS, &drop_frags);
 233     if (!error) {
 234         *drop_fragsp = drop_frags & 1;
 235     }
 236     return error;
 237 }
 238
 239 static int
 240 dpif_linux_set_drop_frags(struct dpif *dpif_, bool drop_frags)
 241 {
 242     int drop_frags_int = drop_frags;
 243     return do_ioctl(dpif_, ODP_SET_DROP_FRAGS, &drop_frags_int);
 244 }
 245
 246 static int
 247 dpif_linux_port_add(struct dpif *dpif_, const char *devname, uint16_t flags,
 248                     uint16_t *port_no)
 249 {
 250     struct odp_port port;
 251     int error;
 252
 253     memset(&port, 0, sizeof port);
 254     strncpy(port.devname, devname, sizeof port.devname);
 255     port.flags = flags;
 256     error = do_ioctl(dpif_, ODP_PORT_ATTACH, &port);
 257     if (!error) {
 258         *port_no = port.port;
 259     }
 260     return error;
 261 }
 262
 263 static int
 264 dpif_linux_port_del(struct dpif *dpif_, uint16_t port_no)
 265 {
 266     int tmp = port_no;
 267     int err;
 268     struct odp_port port;
 269
 270     err = dpif_port_query_by_number(dpif_, port_no, &port);
 271     if (err) {
 272         return err;
 273     }
 274
 275     err = do_ioctl(dpif_, ODP_PORT_DETACH, &tmp);
 276     if (err) {
 277         return err;
 278     }
 279
 280     if (!netdev_is_open(port.devname)) {
 281         /* Try deleting the port if no one has it open.  This shouldn't
 282          * actually be necessary unless the config changed while we weren't
 283          * running but it won't hurt anything if the port is already gone. */
 284         do_ioctl(dpif_, ODP_VPORT_DEL, port.devname);
 285     }
 286
 287     return 0;
 288 }
 289
 290 static int
 291 dpif_linux_port_query_by_number(const struct dpif *dpif_, uint16_t port_no,
 292                           struct odp_port *port)
 293 {
 294     memset(port, 0, sizeof *port);
 295     port->port = port_no;
 296     return do_ioctl(dpif_, ODP_PORT_QUERY, port);
 297 }
 298
 299 static int
 300 dpif_linux_port_query_by_name(const struct dpif *dpif_, const char *devname,
 301                               struct odp_port *port)
 302 {
 303     memset(port, 0, sizeof *port);
 304     strncpy(port->devname, devname, sizeof port->devname);
 305     return do_ioctl(dpif_, ODP_PORT_QUERY, port);
 306 }
 307
 308 static int
 309 dpif_linux_flow_flush(struct dpif *dpif_)
 310 {
 311     return do_ioctl(dpif_, ODP_FLOW_FLUSH, NULL);
 312 }
 313
 314 static int
 315 dpif_linux_port_list(const struct dpif *dpif_, struct odp_port *ports, int n)
 316 {
 317     struct odp_portvec pv;
 318     int error;
 319
 320     pv.ports = ports;
 321     pv.n_ports = n;
 322     error = do_ioctl(dpif_, ODP_PORT_LIST, &pv);
 323     return error ? -error : pv.n_ports;
 324 }
 325
 326 static int
 327 dpif_linux_port_poll(const struct dpif *dpif_, char **devnamep)
 328 {
 329     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 330
 331     if (dpif->change_error) {
 332         dpif->change_error = false;
 333         svec_clear(&dpif->changed_ports);
 334         return ENOBUFS;
 335     } else if (dpif->changed_ports.n) {
 336         *devnamep = dpif->changed_ports.names[--dpif->changed_ports.n];
 337         return 0;
 338     } else {
 339         return EAGAIN;
 340     }
 341 }
 342
 343 static void
 344 dpif_linux_port_poll_wait(const struct dpif *dpif_)
 345 {
 346     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 347     if (dpif->changed_ports.n || dpif->change_error) {
 348         poll_immediate_wake();
 349     } else {
 350         rtnetlink_notifier_wait();
 351     }
 352 }
 353
 354 static int
 355 dpif_linux_port_group_get(const struct dpif *dpif_, int group,
 356                           uint16_t ports[], int n)
 357 {
 358     struct odp_port_group pg;
 359     int error;
 360
 361     assert(n <= UINT16_MAX);
 362     pg.group = group;
 363     pg.ports = ports;
 364     pg.n_ports = n;
 365     error = do_ioctl(dpif_, ODP_PORT_GROUP_GET, &pg);
 366     return error ? -error : pg.n_ports;
 367 }
 368
 369 static int
 370 dpif_linux_port_group_set(struct dpif *dpif_, int group,
 371                           const uint16_t ports[], int n)
 372 {
 373     struct odp_port_group pg;
 374
 375     assert(n <= UINT16_MAX);
 376     pg.group = group;
 377     pg.ports = (uint16_t *) ports;
 378     pg.n_ports = n;
 379     return do_ioctl(dpif_, ODP_PORT_GROUP_SET, &pg);
 380 }
 381
 382 static int
 383 dpif_linux_flow_get(const struct dpif *dpif_, struct odp_flow flows[], int n)
 384 {
 385     struct odp_flowvec fv;
 386     fv.flows = flows;
 387     fv.n_flows = n;
 388     return do_ioctl(dpif_, ODP_FLOW_GET, &fv);
 389 }
 390
 391 static int
 392 dpif_linux_flow_put(struct dpif *dpif_, struct odp_flow_put *put)
 393 {
 394     return do_ioctl(dpif_, ODP_FLOW_PUT, put);
 395 }
 396
 397 static int
 398 dpif_linux_flow_del(struct dpif *dpif_, struct odp_flow *flow)
 399 {
 400     return do_ioctl(dpif_, ODP_FLOW_DEL, flow);
 401 }
 402
 403 static int
 404 dpif_linux_flow_list(const struct dpif *dpif_, struct odp_flow flows[], int n)
 405 {
 406     struct odp_flowvec fv;
 407     int error;
 408
 409     fv.flows = flows;
 410     fv.n_flows = n;
 411     error = do_ioctl(dpif_, ODP_FLOW_LIST, &fv);
 412     return error ? -error : fv.n_flows;
 413 }
 414
 415 static int
 416 dpif_linux_execute(struct dpif *dpif_, uint16_t in_port,
 417                    const union odp_action actions[], int n_actions,
 418                    const struct ofpbuf *buf)
 419 {
 420     struct odp_execute execute;
 421     memset(&execute, 0, sizeof execute);
 422     execute.in_port = in_port;
 423     execute.actions = (union odp_action *) actions;
 424     execute.n_actions = n_actions;
 425     execute.data = buf->data;
 426     execute.length = buf->size;
 427     return do_ioctl(dpif_, ODP_EXECUTE, &execute);
 428 }
 429
 430 static int
 431 dpif_linux_recv_get_mask(const struct dpif *dpif_, int *listen_mask)
 432 {
 433     return do_ioctl(dpif_, ODP_GET_LISTEN_MASK, listen_mask);
 434 }
 435
 436 static int
 437 dpif_linux_recv_set_mask(struct dpif *dpif_, int listen_mask)
 438 {
 439     return do_ioctl(dpif_, ODP_SET_LISTEN_MASK, &listen_mask);
 440 }
 441
 442 static int
 443 dpif_linux_get_sflow_probability(const struct dpif *dpif_,
 444                                  uint32_t *probability)
 445 {
 446     return do_ioctl(dpif_, ODP_GET_SFLOW_PROBABILITY, probability);
 447 }
 448
 449 static int
 450 dpif_linux_set_sflow_probability(struct dpif *dpif_, uint32_t probability)
 451 {
 452     return do_ioctl(dpif_, ODP_SET_SFLOW_PROBABILITY, &probability);
 453 }
 454
 455 static int
 456 dpif_linux_recv(struct dpif *dpif_, struct ofpbuf **bufp)
 457 {
 458     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 459     struct ofpbuf *buf;
 460     int retval;
 461     int error;
 462
 463     buf = ofpbuf_new(65536);
 464     retval = read(dpif->fd, ofpbuf_tail(buf), ofpbuf_tailroom(buf));
 465     if (retval < 0) {
 466         error = errno;
 467         if (error != EAGAIN) {
 468             VLOG_WARN_RL(&error_rl, "%s: read failed: %s",
 469                          dpif_name(dpif_), strerror(error));
 470         }
 471     } else if (retval >= sizeof(struct odp_msg)) {
 472         struct odp_msg *msg = buf->data;
 473         if (msg->length <= retval) {
 474             buf->size += retval;
 475             *bufp = buf;
 476             return 0;
 477         } else {
 478             VLOG_WARN_RL(&error_rl, "%s: discarding message truncated "
 479                          "from %"PRIu32" bytes to %d",
 480                          dpif_name(dpif_), msg->length, retval);
 481             error = ERANGE;
 482         }
 483     } else if (!retval) {
 484         VLOG_WARN_RL(&error_rl, "%s: unexpected end of file", dpif_name(dpif_));
 485         error = EPROTO;
 486     } else {
 487         VLOG_WARN_RL(&error_rl,
 488                      "%s: discarding too-short message (%d bytes)",
 489                      dpif_name(dpif_), retval);
 490         error = ERANGE;
 491     }
 492
 493     *bufp = NULL;
 494     ofpbuf_delete(buf);
 495     return error;
 496 }
 497
 498 static void
 499 dpif_linux_recv_wait(struct dpif *dpif_)
 500 {
 501     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 502     poll_fd_wait(dpif->fd, POLLIN);
 503 }
 504
 505 const struct dpif_class dpif_linux_class = {
 506     "system",
 507     NULL,
 508     NULL,
 509     dpif_linux_enumerate,
 510     dpif_linux_open,
 511     dpif_linux_close,
 512     dpif_linux_get_all_names,
 513     dpif_linux_destroy,
 514     dpif_linux_get_stats,
 515     dpif_linux_get_drop_frags,
 516     dpif_linux_set_drop_frags,
 517     dpif_linux_port_add,
 518     dpif_linux_port_del,
 519     dpif_linux_port_query_by_number,
 520     dpif_linux_port_query_by_name,
 521     dpif_linux_port_list,
 522     dpif_linux_port_poll,
 523     dpif_linux_port_poll_wait,
 524     dpif_linux_port_group_get,
 525     dpif_linux_port_group_set,
 526     dpif_linux_flow_get,
 527     dpif_linux_flow_put,
 528     dpif_linux_flow_del,
 529     dpif_linux_flow_flush,
 530     dpif_linux_flow_list,
 531     dpif_linux_execute,
 532     dpif_linux_recv_get_mask,
 533     dpif_linux_recv_set_mask,
 534     dpif_linux_get_sflow_probability,
 535     dpif_linux_set_sflow_probability,
 536     dpif_linux_recv,
 537     dpif_linux_recv_wait,
 538 };
 539 \f
 540 static int get_openvswitch_major(void);
 541 static int get_major(const char *target);
 542
 543 static int
 544 do_ioctl(const struct dpif *dpif_, int cmd, const void *arg)
 545 {
 546     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 547     return ioctl(dpif->fd, cmd, arg) ? errno : 0;
 548 }
 549
 550 static int
 551 lookup_minor(const char *name, int *minorp)
 552 {
 553     struct ethtool_drvinfo drvinfo;
 554     int minor, port_no;
 555     struct ifreq ifr;
 556     int error;
 557     int sock;
 558
 559     sock = socket(AF_INET, SOCK_DGRAM, 0);
 560     if (sock < 0) {
 561         VLOG_WARN("socket(AF_INET) failed: %s", strerror(errno));
 562         error = errno;
 563         goto error;
 564     }
 565
 566     memset(&ifr, 0, sizeof ifr);
 567     strncpy(ifr.ifr_name, name, sizeof ifr.ifr_name);
 568     ifr.ifr_data = (caddr_t) &drvinfo;
 569
 570     memset(&drvinfo, 0, sizeof drvinfo);
 571     drvinfo.cmd = ETHTOOL_GDRVINFO;
 572     if (ioctl(sock, SIOCETHTOOL, &ifr)) {
 573         VLOG_WARN("ioctl(SIOCETHTOOL) failed: %s", strerror(errno));
 574         error = errno;
 575         goto error_close_sock;
 576     }
 577
 578     if (strcmp(drvinfo.driver, "openvswitch")) {
 579         VLOG_WARN("%s is not an openvswitch device", name);
 580         error = EOPNOTSUPP;
 581         goto error_close_sock;
 582     }
 583
 584     if (sscanf(drvinfo.bus_info, "%d.%d", &minor, &port_no) != 2) {
 585         VLOG_WARN("%s ethtool bus_info has unexpected format", name);
 586         error = EPROTOTYPE;
 587         goto error_close_sock;
 588     } else if (port_no != ODPP_LOCAL) {
 589         /* This is an Open vSwitch device but not the local port.  We
 590          * intentionally support only using the name of the local port as the
 591          * name of a datapath; otherwise, it would be too difficult to
 592          * enumerate all the names of a datapath. */
 593         error = EOPNOTSUPP;
 594         goto error_close_sock;
 595     }
 596
 597     *minorp = minor;
 598     close(sock);
 599     return 0;
 600
 601 error_close_sock:
 602     close(sock);
 603 error:
 604     return error;
 605 }
 606
 607 static int
 608 make_openvswitch_device(int minor, char **fnp)
 609 {
 610     const char dirname[] = "/dev/net";
 611     int major;
 612     dev_t dev;
 613     struct stat s;
 614     char fn[128];
 615
 616     *fnp = NULL;
 617
 618     major = get_openvswitch_major();
 619     if (major < 0) {
 620         return -major;
 621     }
 622     dev = makedev(major, minor);
 623
 624     sprintf(fn, "%s/dp%d", dirname, minor);
 625     if (!stat(fn, &s)) {
 626         if (!S_ISCHR(s.st_mode)) {
 627             VLOG_WARN_RL(&error_rl, "%s is not a character device, fixing",
 628                          fn);
 629         } else if (s.st_rdev != dev) {
 630             VLOG_WARN_RL(&error_rl,
 631                          "%s is device %u:%u but should be %u:%u, fixing",
 632                          fn, major(s.st_rdev), minor(s.st_rdev),
 633                          major(dev), minor(dev));
 634         } else {
 635             goto success;
 636         }
 637         if (unlink(fn)) {
 638             VLOG_WARN_RL(&error_rl, "%s: unlink failed (%s)",
 639                          fn, strerror(errno));
 640             return errno;
 641         }
 642     } else if (errno == ENOENT) {
 643         if (stat(dirname, &s)) {
 644             if (errno == ENOENT) {
 645                 if (mkdir(dirname, 0755)) {
 646                     VLOG_WARN_RL(&error_rl, "%s: mkdir failed (%s)",
 647                                  dirname, strerror(errno));
 648                     return errno;
 649                 }
 650             } else {
 651                 VLOG_WARN_RL(&error_rl, "%s: stat failed (%s)",
 652                              dirname, strerror(errno));
 653                 return errno;
 654             }
 655         }
 656     } else {
 657         VLOG_WARN_RL(&error_rl, "%s: stat failed (%s)", fn, strerror(errno));
 658         return errno;
 659     }
 660
 661     /* The device needs to be created. */
 662     if (mknod(fn, S_IFCHR | 0700, dev)) {
 663         VLOG_WARN_RL(&error_rl,
 664                      "%s: creating character device %u:%u failed (%s)",
 665                      fn, major(dev), minor(dev), strerror(errno));
 666         return errno;
 667     }
 668
 669 success:
 670     *fnp = xstrdup(fn);
 671     return 0;
 672 }
 673
 674 /* Return the major device number of the Open vSwitch device.  If it
 675  * cannot be determined, a negative errno is returned. */
 676 static int
 677 get_openvswitch_major(void)
 678 {
 679     static int openvswitch_major = -1;
 680     if (openvswitch_major < 0) {
 681         openvswitch_major = get_major("openvswitch");
 682     }
 683     return openvswitch_major;
 684 }
 685
 686 static int
 687 get_major(const char *target)
 688 {
 689     const char fn[] = "/proc/devices";
 690     char line[128];
 691     FILE *file;
 692     int ln;
 693
 694     file = fopen(fn, "r");
 695     if (!file) {
 696         VLOG_ERR("opening %s failed (%s)", fn, strerror(errno));
 697         return -errno;
 698     }
 699
 700     for (ln = 1; fgets(line, sizeof line, file); ln++) {
 701         char name[64];
 702         int major;
 703
 704         if (!strncmp(line, "Character", 9) || line[0] == '\0') {
 705             /* Nothing to do. */
 706         } else if (!strncmp(line, "Block", 5)) {
 707             /* We only want character devices, so skip the rest of the file. */
 708             break;
 709         } else if (sscanf(line, "%d %63s", &major, name)) {
 710             if (!strcmp(name, target)) {
 711                 fclose(file);
 712                 return major;
 713             }
 714         } else {
 715             static bool warned;
 716             if (!warned) {
 717                 VLOG_WARN("%s:%d: syntax error", fn, ln);
 718             }
 719             warned = true;
 720         }
 721     }
 722
 723     fclose(file);
 724
 725     VLOG_ERR("%s: %s major not found (is the module loaded?)", fn, target);
 726     return -ENODEV;
 727 }
 728
 729 static int
 730 finish_open(struct dpif *dpif_, const char *local_ifname)
 731 {
 732     struct dpif_linux *dpif = dpif_linux_cast(dpif_);
 733     dpif->local_ifname = xstrdup(local_ifname);
 734     dpif->local_ifindex = if_nametoindex(local_ifname);
 735     if (!dpif->local_ifindex) {
 736         int error = errno;
 737         dpif_uninit(dpif_, true);
 738         VLOG_WARN("could not get ifindex of %s device: %s",
 739                   local_ifname, strerror(errno));
 740         return error;
 741     }
 742     return 0;
 743 }
 744
 745 static int
 746 create_minor(const char *name, int minor, struct dpif **dpifp)
 747 {
 748     int error = open_minor(minor, dpifp);
 749     if (!error) {
 750         error = do_ioctl(*dpifp, ODP_DP_CREATE, name);
 751         if (!error) {
 752             error = finish_open(*dpifp, name);
 753         } else {
 754             dpif_uninit(*dpifp, true);
 755         }
 756     }
 757     return error;
 758 }
 759
 760 static int
 761 open_minor(int minor, struct dpif **dpifp)
 762 {
 763     int error;
 764     char *fn;
 765     int fd;
 766
 767     error = make_openvswitch_device(minor, &fn);
 768     if (error) {
 769         return error;
 770     }
 771
 772     fd = open(fn, O_RDONLY | O_NONBLOCK);
 773     if (fd >= 0) {
 774         struct dpif_linux *dpif = xmalloc(sizeof *dpif);
 775         error = rtnetlink_notifier_register(&dpif->port_notifier,
 776                                            dpif_linux_port_changed, dpif);
 777         if (!error) {
 778             char *name;
 779
 780             name = xasprintf("dp%d", minor);
 781             dpif_init(&dpif->dpif, &dpif_linux_class, name, minor, minor);
 782             free(name);
 783
 784             dpif->fd = fd;
 785             dpif->local_ifname = NULL;
 786             dpif->minor = minor;
 787             dpif->local_ifindex = 0;
 788             svec_init(&dpif->changed_ports);
 789             dpif->change_error = false;
 790             *dpifp = &dpif->dpif;
 791         } else {
 792             free(dpif);
 793         }
 794     } else {
 795         error = errno;
 796         VLOG_WARN("%s: open failed (%s)", fn, strerror(error));
 797     }
 798     free(fn);
 799
 800     return error;
 801 }
 802
 803 static void
 804 dpif_linux_port_changed(const struct rtnetlink_change *change, void *dpif_)
 805 {
 806     struct dpif_linux *dpif = dpif_;
 807
 808     if (change) {
 809         if (change->master_ifindex == dpif->local_ifindex
 810             && (change->nlmsg_type == RTM_NEWLINK
 811                 || change->nlmsg_type == RTM_DELLINK))
 812         {
 813             /* Our datapath changed, either adding a new port or deleting an
 814              * existing one. */
 815             if (!svec_contains(&dpif->changed_ports, change->ifname)) {
 816                 svec_add(&dpif->changed_ports, change->ifname);
 817                 svec_sort(&dpif->changed_ports);
 818             }
 819         }
 820     } else {
 821         dpif->change_error = true;
 822     }
 823 }