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authorDamjan Marion <damarion@cisco.com>2018-12-20 10:44:47 +0100
committerDamjan Marion <dmarion@me.com>2019-01-08 17:03:56 +0000
commite40231b1ecf4b49faaa9ce7b615a7d867104825b (patch)
treef7f7b4fed09740dadee4d270ffb68155a06195a1 /src
parent294afe297c74c7c9413c6bd4856e92c9bc439e7c (diff)
virtio: fix kick race issue
Change-Id: I25b2a28513821bc5eab9ac6890a3964d412b0399 Signed-off-by: Damjan Marion <damarion@cisco.com>
Diffstat (limited to 'src')
-rw-r--r--src/vnet/devices/virtio/device.c10
-rw-r--r--src/vnet/devices/virtio/node.c18
-rw-r--r--src/vnet/devices/virtio/virtio.h11
3 files changed, 29 insertions, 10 deletions
diff --git a/src/vnet/devices/virtio/device.c b/src/vnet/devices/virtio/device.c
index 2b2c853f3ba..7c66a60cf99 100644
--- a/src/vnet/devices/virtio/device.c
+++ b/src/vnet/devices/virtio/device.c
@@ -169,7 +169,6 @@ add_buffer_to_slot (vlib_main_t * vm, virtio_vring_t * vring, u32 bi,
return n_added;
}
-
static_always_inline uword
virtio_interface_tx_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
vlib_frame_t * frame, virtio_if_t * vif)
@@ -184,6 +183,10 @@ virtio_interface_tx_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
clib_spinlock_lock_if_init (&vif->lockp);
+ if ((vring->used->flags & VIRTIO_RING_FLAG_MASK_INT) == 0 &&
+ vring->last_kick_avail_idx != vring->avail->idx)
+ virtio_kick (vring);
+
/* free consumed buffers */
virtio_free_used_desc (vm, vring);
@@ -209,10 +212,7 @@ virtio_interface_tx_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
vring->desc_next = next;
vring->desc_in_use = used;
if ((vring->used->flags & VIRTIO_RING_FLAG_MASK_INT) == 0)
- {
- u64 x = 1;
- CLIB_UNUSED (int r) = write (vring->kick_fd, &x, sizeof (x));
- }
+ virtio_kick (vring);
}
diff --git a/src/vnet/devices/virtio/node.c b/src/vnet/devices/virtio/node.c
index e0195139321..d7a0b3964b4 100644
--- a/src/vnet/devices/virtio/node.c
+++ b/src/vnet/devices/virtio/node.c
@@ -87,17 +87,23 @@ virtio_refill_vring (vlib_main_t * vm, virtio_vring_t * vring)
u16 sz = vring->size;
u16 mask = sz - 1;
+more:
used = vring->desc_in_use;
if (sz - used < sz / 8)
return;
- n_slots = sz - used;
+ /* deliver free buffers in chunks of 64 */
+ n_slots = clib_min (sz - used, 64);
+
next = vring->desc_next;
avail = vring->avail->idx;
n_slots = vlib_buffer_alloc_to_ring (vm, vring->buffers, next, vring->size,
n_slots);
+ if (n_slots == 0)
+ return;
+
while (n_slots)
{
struct vring_desc *d = &vring->desc[next];;
@@ -117,10 +123,8 @@ virtio_refill_vring (vlib_main_t * vm, virtio_vring_t * vring)
vring->desc_in_use = used;
if ((vring->used->flags & VIRTIO_RING_FLAG_MASK_INT) == 0)
- {
- u64 b = 1;
- CLIB_UNUSED (int r) = write (vring->kick_fd, &b, sizeof (b));
- }
+ virtio_kick (vring);
+ goto more;
}
static_always_inline uword
@@ -140,6 +144,10 @@ virtio_device_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
u16 last = vring->last_used_idx;
u16 n_left = vring->used->idx - last;
+ if ((vring->used->flags & VIRTIO_RING_FLAG_MASK_INT) == 0 &&
+ vring->last_kick_avail_idx != vring->avail->idx)
+ virtio_kick (vring);
+
if (n_left == 0)
goto refill;
diff --git a/src/vnet/devices/virtio/virtio.h b/src/vnet/devices/virtio/virtio.h
index e401f2ddcd7..841441bd0c6 100644
--- a/src/vnet/devices/virtio/virtio.h
+++ b/src/vnet/devices/virtio/virtio.h
@@ -87,6 +87,7 @@ typedef struct
u32 call_file_index;
u32 *buffers;
u16 last_used_idx;
+ u16 last_kick_avail_idx;
} virtio_vring_t;
typedef struct
@@ -137,6 +138,16 @@ extern void virtio_free_used_desc (vlib_main_t * vm, virtio_vring_t * vring);
format_function_t format_virtio_device_name;
+static_always_inline void
+virtio_kick (virtio_vring_t * vring)
+{
+ u64 x = 1;
+ int __clib_unused r;
+
+ r = write (vring->kick_fd, &x, sizeof (x));
+ vring->last_kick_avail_idx = vring->avail->idx;
+}
+
#endif /* _VNET_DEVICES_VIRTIO_VIRTIO_H_ */
/*
'#n355'>355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 
/*
 *------------------------------------------------------------------
 * memory_client.c - API message handling, client code.
 *
 * Copyright (c) 2010 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *------------------------------------------------------------------
 */

#include <setjmp.h>

#include <svm/svm.h>
#include <svm/ssvm.h>
#include <vppinfra/serialize.h>
#include <vppinfra/hash.h>
#include <vlibmemory/memory_client.h>
#include <vlibapi/api_common.h>

/* A hack. vl_client_get_first_plugin_msg_id depends on it */
#include <vlibmemory/socket_client.h>

#include <vlibmemory/vl_memory_msg_enum.h>

#define vl_typedefs		/* define message structures */
#include <vlibmemory/vl_memory_api_h.h>
#undef vl_typedefs

#define vl_endianfun		/* define message structures */
#include <vlibmemory/vl_memory_api_h.h>
#undef vl_endianfun

#define vl_calcsizefun
#include <vlibmemory/vl_memory_api_h.h>
#undef vl_calcsizefun

/* instantiate all the print functions we know about */
#define vl_printfun
#include <vlibmemory/vl_memory_api_h.h>
#undef vl_printfun

memory_client_main_t memory_client_main;
__thread memory_client_main_t *my_memory_client_main = &memory_client_main;

typedef struct rx_thread_fn_arg
{
  api_main_t *am;
  memory_client_main_t *mm;
} rx_thread_fn_arg_t;

static void *
rx_thread_fn (void *arg)
{
  rx_thread_fn_arg_t *a = (rx_thread_fn_arg_t *) arg;
  memory_client_main_t *mm;
  svm_queue_t *q;

  vlibapi_set_main (a->am);
  vlibapi_set_memory_client_main (a->mm);
  free (a);

  mm = vlibapi_get_memory_client_main ();
  q = vlibapi_get_main ()->vl_input_queue;

  /* So we can make the rx thread terminate cleanly */
  if (setjmp (mm->rx_thread_jmpbuf) == 0)
    {
      mm->rx_thread_jmpbuf_valid = 1;
      clib_mem_set_thread_index ();
      while (1)
	vl_msg_api_queue_handler (q);
    }
  pthread_exit (0);
}

static void
vl_api_rx_thread_exit_t_handler (vl_api_rx_thread_exit_t * mp)
{
  memory_client_main_t *mm = vlibapi_get_memory_client_main ();
  if (mm->rx_thread_jmpbuf_valid)
    longjmp (mm->rx_thread_jmpbuf, 1);
}

static void
vl_api_name_and_crc_free (void)
{
  api_main_t *am = vlibapi_get_main ();
  int i;
  u8 **keys = 0;
  hash_pair_t *hp;

  if (!am->msg_index_by_name_and_crc)
    return;

  /* *INDENT-OFF* */
  hash_foreach_pair (hp, am->msg_index_by_name_and_crc,
      ({
        vec_add1 (keys, (u8 *) hp->key);
      }));
  /* *INDENT-ON* */
  for (i = 0; i < vec_len (keys); i++)
    vec_free (keys[i]);
  vec_free (keys);
  hash_free (am->msg_index_by_name_and_crc);
}

__clib_nosanitize_addr static void
VL_API_VEC_UNPOISON (const void *v)
{
  const vec_header_t *vh = &((vec_header_t *) v)[-1];
  clib_mem_unpoison (vh, sizeof (*vh) + vec_len (v));
}

static void
vl_api_memclnt_create_reply_t_handler (vl_api_memclnt_create_reply_t * mp)
{
  serialize_main_t _sm, *sm = &_sm;
  api_main_t *am = vlibapi_get_main ();
  u8 *tblv;
  u32 nmsgs;
  int i;
  u8 *name_and_crc;
  u32 msg_index;

  am->my_client_index = mp->index;
  am->my_registration = (vl_api_registration_t *) (uword) mp->handle;

  /* Clean out any previous hash table (unlikely) */
  vl_api_name_and_crc_free ();

  am->msg_index_by_name_and_crc = hash_create_string (0, sizeof (uword));

  /* Recreate the vnet-side API message handler table */
  tblv = uword_to_pointer (mp->message_table, u8 *);
  unserialize_open_data (sm, tblv, vec_len (tblv));
  unserialize_integer (sm, &nmsgs, sizeof (u32));

  VL_API_VEC_UNPOISON (tblv);

  for (i = 0; i < nmsgs; i++)
    {
      msg_index = unserialize_likely_small_unsigned_integer (sm);
      unserialize_cstring (sm, (char **) &name_and_crc);
      hash_set_mem (am->msg_index_by_name_and_crc, name_and_crc, msg_index);
    }
}

void vl_msg_api_send_shmem (svm_queue_t * q, u8 * elem);
int
vl_client_connect (const char *name, int ctx_quota, int input_queue_size)
{
  vl_api_memclnt_create_t *mp;
  vl_api_memclnt_create_reply_t *rp;
  svm_queue_t *vl_input_queue;
  vl_shmem_hdr_t *shmem_hdr;
  int rv = 0;
  void *oldheap;
  api_main_t *am = vlibapi_get_main ();

  if (am->my_registration)
    {
      clib_warning ("client %s already connected...", name);
      return -1;
    }

  if (am->vlib_rp == 0)
    {
      clib_warning ("am->vlib_rp NULL");
      return -1;
    }

  shmem_hdr = am->shmem_hdr;

  if (shmem_hdr == 0 || shmem_hdr->vl_input_queue == 0)
    {
      clib_warning ("shmem_hdr / input queue NULL");
      return -1;
    }

  clib_mem_unpoison (shmem_hdr, sizeof (*shmem_hdr));
  VL_MSG_API_SVM_QUEUE_UNPOISON (shmem_hdr->vl_input_queue);

  oldheap = vl_msg_push_heap ();
  vl_input_queue = svm_queue_alloc_and_init (input_queue_size, sizeof (uword),
					     getpid ());
  vl_msg_pop_heap (oldheap);

  am->my_client_index = ~0;
  am->my_registration = 0;
  am->vl_input_queue = vl_input_queue;

  mp = vl_msg_api_alloc (sizeof (vl_api_memclnt_create_t));
  clib_memset (mp, 0, sizeof (*mp));
  mp->_vl_msg_id = ntohs (VL_API_MEMCLNT_CREATE);
  mp->ctx_quota = ctx_quota;
  mp->input_queue = (uword) vl_input_queue;
  strncpy ((char *) mp->name, name, sizeof (mp->name) - 1);

  vl_msg_api_send_shmem (shmem_hdr->vl_input_queue, (u8 *) & mp);

  while (1)
    {
      int qstatus;
      struct timespec ts, tsrem;
      int i;

      /* Wait up to 10 seconds */
      for (i = 0; i < 1000; i++)
	{
	  qstatus = svm_queue_sub (vl_input_queue, (u8 *) & rp,
				   SVM_Q_NOWAIT, 0);
	  if (qstatus == 0)
	    goto read_one_msg;
	  ts.tv_sec = 0;
	  ts.tv_nsec = 10000 * 1000;	/* 10 ms */
	  while (nanosleep (&ts, &tsrem) < 0)
	    ts = tsrem;
	}
      /* Timeout... */
      clib_warning ("memclnt_create_reply timeout");
      return -1;

    read_one_msg:
      VL_MSG_API_UNPOISON (rp);
      if (ntohs (rp->_vl_msg_id) != VL_API_MEMCLNT_CREATE_REPLY)
	{
	  clib_warning ("unexpected reply: id %d", ntohs (rp->_vl_msg_id));
	  continue;
	}
      rv = clib_net_to_host_u32 (rp->response);

      msgbuf_t *msgbuf = (msgbuf_t *) ((u8 *) rp - offsetof (msgbuf_t, data));
      vl_msg_api_handler ((void *) rp, ntohl (msgbuf->data_len));
      break;
    }
  return (rv);
}

static void
vl_api_memclnt_delete_reply_t_handler (vl_api_memclnt_delete_reply_t * mp)
{
  void *oldheap;
  api_main_t *am = vlibapi_get_main ();

  oldheap = vl_msg_push_heap ();
  svm_queue_free (am->vl_input_queue);
  vl_msg_pop_heap (oldheap);

  am->my_client_index = ~0;
  am->my_registration = 0;
  am->vl_input_queue = 0;
}

void
vl_client_send_disconnect (u8 do_cleanup)
{
  vl_api_memclnt_delete_t *mp;
  vl_shmem_hdr_t *shmem_hdr;
  api_main_t *am = vlibapi_get_main ();

  ASSERT (am->vlib_rp);
  shmem_hdr = am->shmem_hdr;
  ASSERT (shmem_hdr && shmem_hdr->vl_input_queue);

  mp = vl_msg_api_alloc (sizeof (vl_api_memclnt_delete_t));
  clib_memset (mp, 0, sizeof (*mp));
  mp->_vl_msg_id = ntohs (VL_API_MEMCLNT_DELETE);
  mp->index = am->my_client_index;
  mp->handle = (uword) am->my_registration;
  mp->do_cleanup = do_cleanup;

  vl_msg_api_send_shmem (shmem_hdr->vl_input_queue, (u8 *) & mp);
}

int
vl_client_disconnect (void)
{
  vl_api_memclnt_delete_reply_t *rp;
  svm_queue_t *vl_input_queue;
  api_main_t *am = vlibapi_get_main ();
  time_t begin;
  msgbuf_t *msgbuf;

  vl_input_queue = am->vl_input_queue;
  vl_client_send_disconnect (0 /* wait for reply */ );

  /*
   * Have to be careful here, in case the client is disconnecting
   * because e.g. the vlib process died, or is unresponsive.
   */
  begin = time (0);
  while (1)
    {
      time_t now;

      now = time (0);

      if (now >= (begin + 2))
	{
	  clib_warning ("peer unresponsive, give up");
	  am->my_client_index = ~0;
	  am->my_registration = 0;
	  am->shmem_hdr = 0;
	  return -1;
	}
      if (svm_queue_sub (vl_input_queue, (u8 *) & rp, SVM_Q_NOWAIT, 0) < 0)
	continue;

      VL_MSG_API_UNPOISON (rp);

      /* drain the queue */
      if (ntohs (rp->_vl_msg_id) != VL_API_MEMCLNT_DELETE_REPLY)
	{
	  clib_warning ("queue drain: %d", ntohs (rp->_vl_msg_id));
	  msgbuf = (msgbuf_t *) ((u8 *) rp - offsetof (msgbuf_t, data));
	  vl_msg_api_handler ((void *) rp, ntohl (msgbuf->data_len));
	  continue;
	}
      msgbuf = (msgbuf_t *) ((u8 *) rp - offsetof (msgbuf_t, data));
      vl_msg_api_handler ((void *) rp, ntohl (msgbuf->data_len));
      break;
    }

  vl_api_name_and_crc_free ();
  return 0;
}

/**
 * Stave off the binary API dead client reaper
 * Only sent to inactive clients
 */
static void
vl_api_memclnt_keepalive_t_handler (vl_api_memclnt_keepalive_t * mp)
{
  vl_api_memclnt_keepalive_reply_t *rmp;
  api_main_t *am;
  vl_shmem_hdr_t *shmem_hdr;

  am = vlibapi_get_main ();
  shmem_hdr = am->shmem_hdr;

  rmp = vl_msg_api_alloc_as_if_client (sizeof (*rmp));
  clib_memset (rmp, 0, sizeof (*rmp));
  rmp->_vl_msg_id = ntohs (VL_API_MEMCLNT_KEEPALIVE_REPLY);
  rmp->context = mp->context;
  vl_msg_api_send_shmem (shmem_hdr->vl_input_queue, (u8 *) & rmp);
}

#define foreach_api_msg                         \
_(RX_THREAD_EXIT, rx_thread_exit)               \
_(MEMCLNT_CREATE_REPLY, memclnt_create_reply)   \
_(MEMCLNT_DELETE_REPLY, memclnt_delete_reply)	\
_(MEMCLNT_KEEPALIVE, memclnt_keepalive)

void
vl_client_install_client_message_handlers (void)
{
  api_main_t *am = vlibapi_get_main ();
#define _(N, n)                                                               \
  vl_msg_api_config (&(vl_msg_api_msg_config_t){                              \
    .id = VL_API_##N,                                                         \
    .name = #n,                                                               \
    .handler = vl_api_##n##_t_handler,                                        \
    .endian = vl_api_##n##_t_endian,                                          \
    .format_fn = vl_api_##n##_t_format,                                       \
    .size = sizeof (vl_api_##n##_t),                                          \
    .traced = 0,                                                              \
    .tojson = vl_api_##n##_t_tojson,                                          \
    .fromjson = vl_api_##n##_t_fromjson,                                      \
    .calc_size = vl_api_##n##_t_calc_size,                                    \
  });                                                                         \
  am->msg_data[VL_API_##N].replay_allowed = 0;
  foreach_api_msg;
#undef _
}

int
vl_client_api_map (const char *region_name)
{
  int rv;

  if ((rv = vl_map_shmem (region_name, 0 /* is_vlib */ )) < 0)
    return rv;

  vl_client_install_client_message_handlers ();
  return 0;
}

void
vl_client_api_unmap (void)
{
  vl_unmap_shmem_client ();
}

u8
vl_mem_client_is_connected (void)
{
  return (my_memory_client_main->connected_to_vlib != 0);
}

static int
connect_to_vlib_internal (const char *svm_name,
			  const char *client_name,
			  int rx_queue_size, void *(*thread_fn) (void *),
			  void *thread_fn_arg, int do_map)
{
  int rv = 0;
  memory_client_main_t *mm = vlibapi_get_memory_client_main ();
  api_main_t *am = vlibapi_get_main ();

  if (do_map && (rv = vl_client_api_map (svm_name)))
    {
      clib_warning ("vl_client_api map rv %d", rv);
      return rv;
    }

  if (vl_client_connect (client_name, 0 /* punt quota */ ,
			 rx_queue_size /* input queue */ ) < 0)
    {
      vl_client_api_unmap ();
      return -1;
    }

  /* Start the rx queue thread */

  if (thread_fn)
    {
      if (thread_fn == rx_thread_fn)
	{
	  rx_thread_fn_arg_t *arg;
	  arg = malloc (sizeof (*arg));
	  arg->am = vlibapi_get_main ();
	  arg->mm = vlibapi_get_memory_client_main ();
	  thread_fn_arg = (void *) arg;
	}

      rv = pthread_create (&mm->rx_thread_handle,
			   NULL /*attr */ , thread_fn, thread_fn_arg);
      if (rv)
	{
	  clib_warning ("pthread_create returned %d", rv);
	  am->rx_thread_handle = 0;
	}
      else
	{
	  am->rx_thread_handle = mm->rx_thread_handle;
	}
    }

  mm->connected_to_vlib = 1;
  return 0;
}

int
vl_client_connect_to_vlib (const char *svm_name,
			   const char *client_name, int rx_queue_size)
{
  return connect_to_vlib_internal (svm_name, client_name, rx_queue_size,
				   rx_thread_fn, 0 /* thread fn arg */ ,
				   1 /* do map */ );
}

int
vl_client_connect_to_vlib_no_rx_pthread (const char *svm_name,
					 const char *client_name,
					 int rx_queue_size)
{
  return connect_to_vlib_internal (svm_name, client_name, rx_queue_size,
				   0 /* no rx_thread_fn */ ,
				   0 /* no thread fn arg */ ,
				   1 /* do map */ );
}

int
vl_client_connect_to_vlib_no_map (const char *svm_name,
				  const char *client_name, int rx_queue_size)
{
  return connect_to_vlib_internal (svm_name, client_name, rx_queue_size,
				   rx_thread_fn, 0 /* no thread fn arg */ ,
				   0 /* dont map */ );
}

int
vl_client_connect_to_vlib_no_rx_pthread_no_map (const char *svm_name,
						const char *client_name,
						int rx_queue_size)
{
  return connect_to_vlib_internal (svm_name, client_name, rx_queue_size,
				   0 /* no thread_fn */ ,
				   0 /* no thread fn arg */ ,
				   0 /* dont map */ );
}

int
vl_client_connect_to_vlib_thread_fn (const char *svm_name,
				     const char *client_name,
				     int rx_queue_size,
				     void *(*thread_fn) (void *), void *arg)
{
  return connect_to_vlib_internal (svm_name, client_name, rx_queue_size,
				   thread_fn, arg, 1 /* do map */ );
}


static void
disconnect_from_vlib_internal (u8 do_unmap)
{
  memory_client_main_t *mm = vlibapi_get_memory_client_main ();
  api_main_t *am = vlibapi_get_main ();
  uword junk;

  if (mm->rx_thread_jmpbuf_valid)
    {
      vl_api_rx_thread_exit_t *ep;
      ep = vl_msg_api_alloc (sizeof (*ep));
      ep->_vl_msg_id = ntohs (VL_API_RX_THREAD_EXIT);
      vl_msg_api_send_shmem (am->vl_input_queue, (u8 *) & ep);
      pthread_join (mm->rx_thread_handle, (void **) &junk);
    }
  if (mm->connected_to_vlib)
    {
      vl_client_disconnect ();
      if (do_unmap)
	vl_client_api_unmap ();
    }
  clib_memset (mm, 0, sizeof (*mm));
}

void
vl_client_disconnect_from_vlib (void)
{
  disconnect_from_vlib_internal (1);
}

void
vl_client_disconnect_from_vlib_no_unmap (void)
{
  disconnect_from_vlib_internal (0);
}

static void vl_api_get_first_msg_id_reply_t_handler
  (vl_api_get_first_msg_id_reply_t * mp)
{
  memory_client_main_t *mm = vlibapi_get_memory_client_main ();
  i32 retval = ntohl (mp->retval);

  mm->first_msg_id_reply = (retval >= 0) ? ntohs (mp->first_msg_id) : ~0;
  mm->first_msg_id_reply_ready = 1;
}

u16
vl_client_get_first_plugin_msg_id (const char *plugin_name)
{
  vl_api_get_first_msg_id_t *mp;
  api_main_t *am = vlibapi_get_main ();
  memory_client_main_t *mm = vlibapi_get_memory_client_main ();
  vl_api_msg_data_t *m =
    vl_api_get_msg_data (am, VL_API_GET_FIRST_MSG_ID_REPLY);
  f64 timeout;
  void *old_handler;
  clib_time_t clib_time;
  u16 rv = ~0;

  if (strlen (plugin_name) + 1 > sizeof (mp->name))
    return (rv);

  clib_memset (&clib_time, 0, sizeof (clib_time));
  clib_time_init (&clib_time);

  /* Push this plugin's first_msg_id_reply handler */
  old_handler = m->handler;
  m->handler = (void *) vl_api_get_first_msg_id_reply_t_handler;
  if (!m->calc_size_func)
    {
      m->calc_size_func =
	(uword (*) (void *)) vl_api_get_first_msg_id_reply_t_calc_size;
    }

  /* Ask the data-plane for the message-ID base of the indicated plugin */
  mm->first_msg_id_reply_ready = 0;

  /* Not using shm client */
  if (!am->my_registration)
    {
      mp = vl_socket_client_msg_alloc (sizeof (*mp));
      clib_memset (mp, 0, sizeof (*mp));
      mp->_vl_msg_id = ntohs (VL_API_GET_FIRST_MSG_ID);
      mp->client_index = am->my_client_index;
      strncpy ((char *) mp->name, plugin_name, sizeof (mp->name) - 1);

      if (vl_socket_client_write () <= 0)
	goto sock_err;
      if (vl_socket_client_read (1))
	goto sock_err;

      if (mm->first_msg_id_reply_ready == 1)
	{
	  rv = mm->first_msg_id_reply;
	  goto result;
	}

    sock_err:
      /* Restore old handler */
      m->handler = old_handler;

      return -1;
    }
  else
    {
      mp = vl_msg_api_alloc (sizeof (*mp));
      clib_memset (mp, 0, sizeof (*mp));
      mp->_vl_msg_id = ntohs (VL_API_GET_FIRST_MSG_ID);
      mp->client_index = am->my_client_index;
      strncpy ((char *) mp->name, plugin_name, sizeof (mp->name) - 1);

      vl_msg_api_send_shmem (am->shmem_hdr->vl_input_queue, (u8 *) & mp);

      /* Synchronously wait for the answer */
      timeout = clib_time_now (&clib_time) + 1.0;
      while (clib_time_now (&clib_time) < timeout)
	{
	  if (mm->first_msg_id_reply_ready == 1)
	    {
	      rv = mm->first_msg_id_reply;
	      goto result;
	    }
	}
      /* Restore old handler */
      m->handler = old_handler;

      return rv;
    }

result:

  /* Restore the old handler */
  m->handler = old_handler;

  if (rv == (u16) ~ 0)
    clib_warning ("plugin '%s' not registered", plugin_name);

  return rv;
}

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */