src/vnet/session/segment_manager.c - fdio/vpp - Gitiles

 /*
  * Copyright (c) 2017 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 <vnet/session/segment_manager.h>
 #include <vnet/session/session.h>
 #include <vnet/session/application.h>

 /**
  * Counter used to build segment names
  */
 u32 segment_name_counter = 0;

 /**
  * Pool of segment managers
  */
 segment_manager_t *segment_managers = 0;

 /**
  * Process private segment index
  */
 u32 *private_segment_indices;

 /**
  * Default fifo and segment size. TODO config.
  */
 u32 default_fifo_size = 1 << 16;
 u32 default_segment_size = 1 << 20;

 void
 segment_manager_get_segment_info (u32 index, u8 ** name, u32 * size)
 {
   svm_fifo_segment_private_t *s;
   s = svm_fifo_get_segment (index);
   *name = s->h->segment_name;
   *size = s->ssvm.ssvm_size;
 }

 always_inline int
 session_manager_add_segment_i (segment_manager_t * sm, u32 segment_size,
 			       u8 * segment_name)
 {
   svm_fifo_segment_create_args_t _ca, *ca = &_ca;
   int rv;

   memset (ca, 0, sizeof (*ca));

   ca->segment_name = (char *) segment_name;
   ca->segment_size = segment_size;
   ca->rx_fifo_size = sm->properties->rx_fifo_size;
   ca->tx_fifo_size = sm->properties->tx_fifo_size;
   ca->preallocated_fifo_pairs = sm->properties->preallocated_fifo_pairs;

   rv = svm_fifo_segment_create (ca);
   if (rv)
     {
       clib_warning ("svm_fifo_segment_create ('%s', %d) failed",
 		    ca->segment_name, ca->segment_size);
       return VNET_API_ERROR_SVM_SEGMENT_CREATE_FAIL;
     }

   vec_append (sm->segment_indices, ca->new_segment_indices);
   vec_free (ca->new_segment_indices);

   return 0;
 }

 int
 session_manager_add_segment (segment_manager_t * sm)
 {
   u8 *segment_name;
   svm_fifo_segment_create_args_t _ca, *ca = &_ca;
   u32 add_segment_size;
   int rv;

   memset (ca, 0, sizeof (*ca));
   segment_name = format (0, "%d-%d%c", getpid (), segment_name_counter++, 0);
   add_segment_size = sm->properties->add_segment_size ?
     sm->properties->add_segment_size : default_segment_size;

   rv = session_manager_add_segment_i (sm, add_segment_size, segment_name);
   vec_free (segment_name);
   return rv;
 }

 int
 session_manager_add_first_segment (segment_manager_t * sm, u32 segment_size)
 {
   u8 *segment_name;
   int rv;

   segment_name = format (0, "%d-%d%c", getpid (), segment_name_counter++, 0);
   rv = session_manager_add_segment_i (sm, segment_size, segment_name);
   vec_free (segment_name);
   return rv;
 }

 static void
   segment_manager_alloc_process_private_segment
   (segment_manager_properties_t * props)
 {
   svm_fifo_segment_create_args_t _a, *a = &_a;

   if (private_segment_indices)
     return;

   memset (a, 0, sizeof (*a));
   a->segment_name = "process-private-segment";
   a->segment_size = ~0;
   a->rx_fifo_size = props->rx_fifo_size;
   a->tx_fifo_size = props->tx_fifo_size;
   a->preallocated_fifo_pairs = props->preallocated_fifo_pairs;
   a->private_segment_count = props->private_segment_count;
   a->private_segment_size = props->private_segment_size;

   if (svm_fifo_segment_create_process_private (a))
     clib_warning ("Failed to create process private segment");

   private_segment_indices = a->new_segment_indices;
   ASSERT (vec_len (private_segment_indices));
 }

 /**
  * Initializes segment manager based on options provided.
  * Returns error if svm segment allocation fails.
  */
 int
 segment_manager_init (segment_manager_t * sm,
 		      segment_manager_properties_t * properties,
 		      u32 first_seg_size)
 {
   int rv;

   /* app allocates these */
   sm->properties = properties;

   first_seg_size = first_seg_size > 0 ? first_seg_size : default_segment_size;

   if (sm->properties->use_private_segment == 0)
     {
       rv = session_manager_add_first_segment (sm, first_seg_size);
       if (rv)
 	{
 	  clib_warning ("Failed to allocate segment");
 	  return rv;
 	}
     }
   else
     {
       if (vec_len (private_segment_indices) == 0)
 	segment_manager_alloc_process_private_segment (properties);
       ASSERT (vec_len (private_segment_indices));
       vec_append (sm->segment_indices, private_segment_indices);
     }

   clib_spinlock_init (&sm->lockp);
   return 0;
 }

 void
 segment_manager_first_segment_maybe_del (segment_manager_t * sm)
 {
   svm_fifo_segment_private_t *fifo_segment;

   /* If the first semgment has no fifos, then delete the 1st segment
    */
   fifo_segment = svm_fifo_get_segment (sm->segment_indices[0]);
   if (!svm_fifo_segment_has_fifos (fifo_segment))
     {
       clib_spinlock_lock (&sm->lockp);
       svm_fifo_segment_delete (fifo_segment);
       vec_del1 (sm->segment_indices, 0);
       clib_spinlock_unlock (&sm->lockp);
     }
 }

   /**
  * Removes segment manager.
  *
  * Since the fifos allocated in the segment keep backpointers to the sessions
  * prior to removing the segment, we call session disconnect. This
  * subsequently propages into transport.
  */
 void
 segment_manager_del (segment_manager_t * sm)
 {
   int j;
   svm_fifo_segment_private_t *fifo_segment;
   ASSERT (vec_len (sm->segment_indices));

   /* Across all fifo segments used by the server */
   for (j = 0; j < vec_len (sm->segment_indices); j++)
     {
       svm_fifo_t *fifo;

       /* Vector of fifos allocated in the segment */
       fifo_segment = svm_fifo_get_segment (sm->segment_indices[j]);
       fifo = svm_fifo_segment_get_fifo_list (fifo_segment);

       /*
        * Remove any residual sessions from the session lookup table
        * Don't bother deleting the individual fifos, we're going to
        * throw away the fifo segment in a minute.
        */
       while (fifo)
 	{
 	  u32 session_index, thread_index;
 	  stream_session_t *session;

 	  session_index = fifo->master_session_index;
 	  thread_index = fifo->master_thread_index;

 	  session = stream_session_get (session_index, thread_index);

 	  /* Instead of directly removing the session call disconnect */
 	  session->session_state = SESSION_STATE_CLOSED;
 	  session_send_session_evt_to_thread (stream_session_handle (session),
 					      FIFO_EVENT_DISCONNECT,
 					      thread_index);
 	  fifo = fifo->next;
 	}

       /* Instead of removing the segment, test when cleaning up disconnected
        * sessions if the segment can be removed.
        */
     }

   segment_manager_first_segment_maybe_del (sm);

   clib_spinlock_free (&sm->lockp);
   pool_put (segment_managers, sm);
 }

 static int
 segment_manager_notify_app_seg_add (segment_manager_t * sm,
 				    u32 fifo_segment_index)
 {
   application_t *app = application_get (sm->app_index);
   u32 seg_size = 0;
   u8 *seg_name;

   /* Send an API message to the external app, to map new segment */
   ASSERT (app->cb_fns.add_segment_callback);

   segment_manager_get_segment_info (fifo_segment_index, &seg_name, &seg_size);
   return app->cb_fns.add_segment_callback (app->api_client_index, seg_name,
 					   seg_size);
 }

 int
 segment_manager_alloc_session_fifos (segment_manager_t * sm,
 				     svm_fifo_t ** server_rx_fifo,
 				     svm_fifo_t ** server_tx_fifo,
 				     u32 * fifo_segment_index)
 {
   svm_fifo_segment_private_t *fifo_segment;
   u32 fifo_size, sm_index;
   u8 added_a_segment = 0;
   int i;

   ASSERT (vec_len (sm->segment_indices));

   /* Make sure we don't have multiple threads trying to allocate segments
    * at the same time. */
   clib_spinlock_lock (&sm->lockp);

   /* Allocate svm fifos */
 again:
   for (i = 0; i < vec_len (sm->segment_indices); i++)
     {
       *fifo_segment_index = sm->segment_indices[i];
       fifo_segment = svm_fifo_get_segment (*fifo_segment_index);

       /* FC: cleanup, make sure sm->properties->xxx_fifo_size always set */
       fifo_size = sm->properties->rx_fifo_size;
       fifo_size = (fifo_size == 0) ? default_fifo_size : fifo_size;
       *server_rx_fifo =
 	svm_fifo_segment_alloc_fifo (fifo_segment, fifo_size,
 				     FIFO_SEGMENT_RX_FREELIST);

       /* FC: cleanup, make sure sm->properties->xxx_fifo_size always set */
       fifo_size = sm->properties->tx_fifo_size;
       fifo_size = (fifo_size == 0) ? default_fifo_size : fifo_size;
       *server_tx_fifo =
 	svm_fifo_segment_alloc_fifo (fifo_segment, fifo_size,
 				     FIFO_SEGMENT_TX_FREELIST);

       if (*server_rx_fifo == 0)
 	{
 	  /* This would be very odd, but handle it... */
 	  if (*server_tx_fifo != 0)
 	    {
 	      svm_fifo_segment_free_fifo (fifo_segment, *server_tx_fifo,
 					  FIFO_SEGMENT_TX_FREELIST);
 	      *server_tx_fifo = 0;
 	    }
 	  continue;
 	}
       if (*server_tx_fifo == 0)
 	{
 	  if (*server_rx_fifo != 0)
 	    {
 	      svm_fifo_segment_free_fifo (fifo_segment, *server_rx_fifo,
 					  FIFO_SEGMENT_RX_FREELIST);
 	      *server_rx_fifo = 0;
 	    }
 	  continue;
 	}
       break;
     }

   /* See if we're supposed to create another segment */
   if (*server_rx_fifo == 0)
     {
       if (sm->properties->add_segment && !sm->properties->use_private_segment)
 	{
 	  if (added_a_segment)
 	    {
 	      clib_warning ("added a segment, still cant allocate a fifo");
 	      clib_spinlock_unlock (&sm->lockp);
 	      return SESSION_ERROR_NEW_SEG_NO_SPACE;
 	    }

 	  if (session_manager_add_segment (sm))
 	    {
 	      clib_spinlock_unlock (&sm->lockp);
 	      return VNET_API_ERROR_URI_FIFO_CREATE_FAILED;
 	    }

 	  added_a_segment = 1;
 	  goto again;
 	}
       else
 	{
 	  clib_warning ("No space to allocate fifos!");
 	  clib_spinlock_unlock (&sm->lockp);
 	  return SESSION_ERROR_NO_SPACE;
 	}
     }

   /* Backpointers to segment manager */
   sm_index = segment_manager_index (sm);
   (*server_tx_fifo)->segment_manager = sm_index;
   (*server_rx_fifo)->segment_manager = sm_index;

   clib_spinlock_unlock (&sm->lockp);

   if (added_a_segment)
     return segment_manager_notify_app_seg_add (sm, *fifo_segment_index);

   return 0;
 }

 void
 segment_manager_dealloc_fifos (u32 svm_segment_index, svm_fifo_t * rx_fifo,
 			       svm_fifo_t * tx_fifo)
 {
   segment_manager_t *sm;
   svm_fifo_segment_private_t *fifo_segment;

   sm = segment_manager_get_if_valid (rx_fifo->segment_manager);

   /* It's possible to have no segment manager if the session was removed
    * as result of a detach */
   if (!sm)
     return;

   fifo_segment = svm_fifo_get_segment (svm_segment_index);
   svm_fifo_segment_free_fifo (fifo_segment, rx_fifo,
 			      FIFO_SEGMENT_RX_FREELIST);
   svm_fifo_segment_free_fifo (fifo_segment, tx_fifo,
 			      FIFO_SEGMENT_TX_FREELIST);

   /* Don't try to delete process-private segments */
   if (sm->properties->private_segment_count > 0)
     return;

   /* Remove segment only if it holds no fifos and not the first */
   if (sm->segment_indices[0] != svm_segment_index
       && !svm_fifo_segment_has_fifos (fifo_segment))
     {
       clib_spinlock_lock (&sm->lockp);
       svm_fifo_segment_delete (fifo_segment);
       vec_del1 (sm->segment_indices, svm_segment_index);
       clib_spinlock_unlock (&sm->lockp);
     }
 }

 /**
  * Allocates shm queue in the first segment
  */
 unix_shared_memory_queue_t *
 segment_manager_alloc_queue (segment_manager_t * sm, u32 queue_size)
 {
   ssvm_shared_header_t *sh;
   svm_fifo_segment_private_t *segment;
   unix_shared_memory_queue_t *q;
   void *oldheap;

   ASSERT (sm->segment_indices != 0);

   segment = svm_fifo_get_segment (sm->segment_indices[0]);
   sh = segment->ssvm.sh;

   oldheap = ssvm_push_heap (sh);
   q =
     unix_shared_memory_queue_init (queue_size, sizeof (session_fifo_event_t),
 				   0 /* consumer pid */ , 0
 				   /* signal when queue non-empty */ );
   ssvm_pop_heap (oldheap);
   return q;
 }

 /**
  * Frees shm queue allocated in the first segment
  */
 void
 segment_manager_dealloc_queue (segment_manager_t * sm,
 			       unix_shared_memory_queue_t * q)
 {
   ssvm_shared_header_t *sh;
   svm_fifo_segment_private_t *segment;
   void *oldheap;

   ASSERT (sm->segment_indices != 0);

   segment = svm_fifo_get_segment (sm->segment_indices[0]);
   sh = segment->ssvm.sh;

   oldheap = ssvm_push_heap (sh);
   unix_shared_memory_queue_free (q);
   ssvm_pop_heap (oldheap);
 }

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	* Copyright (c) 2017 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 <vnet/session/segment_manager.h>
	#include <vnet/session/session.h>
	#include <vnet/session/application.h>

	/**
	* Counter used to build segment names
	*/
	u32 segment_name_counter = 0;

	/**
	* Pool of segment managers
	*/
	segment_manager_t *segment_managers = 0;

	/**
	* Process private segment index
	*/
	u32 *private_segment_indices;

	/**
	* Default fifo and segment size. TODO config.
	*/
	u32 default_fifo_size = 1 << 16;
	u32 default_segment_size = 1 << 20;

	void
	segment_manager_get_segment_info (u32 index, u8 ** name, u32 * size)
	{
	svm_fifo_segment_private_t *s;
	s = svm_fifo_get_segment (index);
	*name = s->h->segment_name;
	*size = s->ssvm.ssvm_size;
	}

	always_inline int
	session_manager_add_segment_i (segment_manager_t * sm, u32 segment_size,
	u8 * segment_name)
	{
	svm_fifo_segment_create_args_t _ca, *ca = &_ca;
	int rv;

	memset (ca, 0, sizeof (*ca));

	ca->segment_name = (char *) segment_name;
	ca->segment_size = segment_size;
	ca->rx_fifo_size = sm->properties->rx_fifo_size;
	ca->tx_fifo_size = sm->properties->tx_fifo_size;
	ca->preallocated_fifo_pairs = sm->properties->preallocated_fifo_pairs;

	rv = svm_fifo_segment_create (ca);
	if (rv)
	{
	clib_warning ("svm_fifo_segment_create ('%s', %d) failed",
	ca->segment_name, ca->segment_size);
	return VNET_API_ERROR_SVM_SEGMENT_CREATE_FAIL;
	}

	vec_append (sm->segment_indices, ca->new_segment_indices);
	vec_free (ca->new_segment_indices);

	return 0;
	}

	int
	session_manager_add_segment (segment_manager_t * sm)
	{
	u8 *segment_name;
	svm_fifo_segment_create_args_t _ca, *ca = &_ca;
	u32 add_segment_size;
	int rv;

	memset (ca, 0, sizeof (*ca));
	segment_name = format (0, "%d-%d%c", getpid (), segment_name_counter++, 0);
	add_segment_size = sm->properties->add_segment_size ?
	sm->properties->add_segment_size : default_segment_size;

	rv = session_manager_add_segment_i (sm, add_segment_size, segment_name);
	vec_free (segment_name);
	return rv;
	}

	int
	session_manager_add_first_segment (segment_manager_t * sm, u32 segment_size)
	{
	u8 *segment_name;
	int rv;

	segment_name = format (0, "%d-%d%c", getpid (), segment_name_counter++, 0);
	rv = session_manager_add_segment_i (sm, segment_size, segment_name);
	vec_free (segment_name);
	return rv;
	}

	static void
	segment_manager_alloc_process_private_segment
	(segment_manager_properties_t * props)
	{
	svm_fifo_segment_create_args_t _a, *a = &_a;

	if (private_segment_indices)
	return;

	memset (a, 0, sizeof (*a));
	a->segment_name = "process-private-segment";
	a->segment_size = ~0;
	a->rx_fifo_size = props->rx_fifo_size;
	a->tx_fifo_size = props->tx_fifo_size;
	a->preallocated_fifo_pairs = props->preallocated_fifo_pairs;
	a->private_segment_count = props->private_segment_count;
	a->private_segment_size = props->private_segment_size;

	if (svm_fifo_segment_create_process_private (a))
	clib_warning ("Failed to create process private segment");

	private_segment_indices = a->new_segment_indices;
	ASSERT (vec_len (private_segment_indices));
	}

	/**
	* Initializes segment manager based on options provided.
	* Returns error if svm segment allocation fails.
	*/
	int
	segment_manager_init (segment_manager_t * sm,
	segment_manager_properties_t * properties,
	u32 first_seg_size)
	{
	int rv;

	/* app allocates these */
	sm->properties = properties;

	first_seg_size = first_seg_size > 0 ? first_seg_size : default_segment_size;

	if (sm->properties->use_private_segment == 0)
	{
	rv = session_manager_add_first_segment (sm, first_seg_size);
	if (rv)
	{
	clib_warning ("Failed to allocate segment");
	return rv;
	}
	}
	else
	{
	if (vec_len (private_segment_indices) == 0)
	segment_manager_alloc_process_private_segment (properties);
	ASSERT (vec_len (private_segment_indices));
	vec_append (sm->segment_indices, private_segment_indices);
	}

	clib_spinlock_init (&sm->lockp);
	return 0;
	}

	void
	segment_manager_first_segment_maybe_del (segment_manager_t * sm)
	{
	svm_fifo_segment_private_t *fifo_segment;

	/* If the first semgment has no fifos, then delete the 1st segment
	*/
	fifo_segment = svm_fifo_get_segment (sm->segment_indices[0]);
	if (!svm_fifo_segment_has_fifos (fifo_segment))
	{
	clib_spinlock_lock (&sm->lockp);
	svm_fifo_segment_delete (fifo_segment);
	vec_del1 (sm->segment_indices, 0);
	clib_spinlock_unlock (&sm->lockp);
	}
	}

	/**
	* Removes segment manager.
	*
	* Since the fifos allocated in the segment keep backpointers to the sessions
	* prior to removing the segment, we call session disconnect. This
	* subsequently propages into transport.
	*/
	void
	segment_manager_del (segment_manager_t * sm)
	{
	int j;
	svm_fifo_segment_private_t *fifo_segment;
	ASSERT (vec_len (sm->segment_indices));

	/* Across all fifo segments used by the server */
	for (j = 0; j < vec_len (sm->segment_indices); j++)
	{
	svm_fifo_t *fifo;

	/* Vector of fifos allocated in the segment */
	fifo_segment = svm_fifo_get_segment (sm->segment_indices[j]);
	fifo = svm_fifo_segment_get_fifo_list (fifo_segment);

	/*
	* Remove any residual sessions from the session lookup table
	* Don't bother deleting the individual fifos, we're going to
	* throw away the fifo segment in a minute.
	*/
	while (fifo)
	{
	u32 session_index, thread_index;
	stream_session_t *session;

	session_index = fifo->master_session_index;
	thread_index = fifo->master_thread_index;

	session = stream_session_get (session_index, thread_index);

	/* Instead of directly removing the session call disconnect */
	session->session_state = SESSION_STATE_CLOSED;
	session_send_session_evt_to_thread (stream_session_handle (session),
	FIFO_EVENT_DISCONNECT,
	thread_index);
	fifo = fifo->next;
	}

	/* Instead of removing the segment, test when cleaning up disconnected
	* sessions if the segment can be removed.
	*/
	}

	segment_manager_first_segment_maybe_del (sm);

	clib_spinlock_free (&sm->lockp);
	pool_put (segment_managers, sm);
	}

	static int
	segment_manager_notify_app_seg_add (segment_manager_t * sm,
	u32 fifo_segment_index)
	{
	application_t *app = application_get (sm->app_index);
	u32 seg_size = 0;
	u8 *seg_name;

	/* Send an API message to the external app, to map new segment */
	ASSERT (app->cb_fns.add_segment_callback);

	segment_manager_get_segment_info (fifo_segment_index, &seg_name, &seg_size);
	return app->cb_fns.add_segment_callback (app->api_client_index, seg_name,
	seg_size);
	}

	int
	segment_manager_alloc_session_fifos (segment_manager_t * sm,
	svm_fifo_t ** server_rx_fifo,
	svm_fifo_t ** server_tx_fifo,
	u32 * fifo_segment_index)
	{
	svm_fifo_segment_private_t *fifo_segment;
	u32 fifo_size, sm_index;
	u8 added_a_segment = 0;
	int i;

	ASSERT (vec_len (sm->segment_indices));

	/* Make sure we don't have multiple threads trying to allocate segments
	* at the same time. */
	clib_spinlock_lock (&sm->lockp);

	/* Allocate svm fifos */
	again:
	for (i = 0; i < vec_len (sm->segment_indices); i++)
	{
	*fifo_segment_index = sm->segment_indices[i];
	fifo_segment = svm_fifo_get_segment (*fifo_segment_index);

	/* FC: cleanup, make sure sm->properties->xxx_fifo_size always set */
	fifo_size = sm->properties->rx_fifo_size;
	fifo_size = (fifo_size == 0) ? default_fifo_size : fifo_size;
	*server_rx_fifo =
	svm_fifo_segment_alloc_fifo (fifo_segment, fifo_size,
	FIFO_SEGMENT_RX_FREELIST);

	/* FC: cleanup, make sure sm->properties->xxx_fifo_size always set */
	fifo_size = sm->properties->tx_fifo_size;
	fifo_size = (fifo_size == 0) ? default_fifo_size : fifo_size;
	*server_tx_fifo =
	svm_fifo_segment_alloc_fifo (fifo_segment, fifo_size,
	FIFO_SEGMENT_TX_FREELIST);

	if (*server_rx_fifo == 0)
	{
	/* This would be very odd, but handle it... */
	if (*server_tx_fifo != 0)
	{
	svm_fifo_segment_free_fifo (fifo_segment, *server_tx_fifo,
	FIFO_SEGMENT_TX_FREELIST);
	*server_tx_fifo = 0;
	}
	continue;
	}
	if (*server_tx_fifo == 0)
	{
	if (*server_rx_fifo != 0)
	{
	svm_fifo_segment_free_fifo (fifo_segment, *server_rx_fifo,
	FIFO_SEGMENT_RX_FREELIST);
	*server_rx_fifo = 0;
	}
	continue;
	}
	break;
	}

	/* See if we're supposed to create another segment */
	if (*server_rx_fifo == 0)
	{
	if (sm->properties->add_segment && !sm->properties->use_private_segment)
	{
	if (added_a_segment)
	{
	clib_warning ("added a segment, still cant allocate a fifo");
	clib_spinlock_unlock (&sm->lockp);
	return SESSION_ERROR_NEW_SEG_NO_SPACE;
	}

	if (session_manager_add_segment (sm))
	{
	clib_spinlock_unlock (&sm->lockp);
	return VNET_API_ERROR_URI_FIFO_CREATE_FAILED;
	}

	added_a_segment = 1;
	goto again;
	}
	else
	{
	clib_warning ("No space to allocate fifos!");
	clib_spinlock_unlock (&sm->lockp);
	return SESSION_ERROR_NO_SPACE;
	}
	}

	/* Backpointers to segment manager */
	sm_index = segment_manager_index (sm);
	(*server_tx_fifo)->segment_manager = sm_index;
	(*server_rx_fifo)->segment_manager = sm_index;

	clib_spinlock_unlock (&sm->lockp);

	if (added_a_segment)
	return segment_manager_notify_app_seg_add (sm, *fifo_segment_index);

	return 0;
	}

	void
	segment_manager_dealloc_fifos (u32 svm_segment_index, svm_fifo_t * rx_fifo,
	svm_fifo_t * tx_fifo)
	{
	segment_manager_t *sm;
	svm_fifo_segment_private_t *fifo_segment;

	sm = segment_manager_get_if_valid (rx_fifo->segment_manager);

	/* It's possible to have no segment manager if the session was removed
	* as result of a detach */
	if (!sm)
	return;

	fifo_segment = svm_fifo_get_segment (svm_segment_index);
	svm_fifo_segment_free_fifo (fifo_segment, rx_fifo,
	FIFO_SEGMENT_RX_FREELIST);
	svm_fifo_segment_free_fifo (fifo_segment, tx_fifo,
	FIFO_SEGMENT_TX_FREELIST);

	/* Don't try to delete process-private segments */
	if (sm->properties->private_segment_count > 0)
	return;

	/* Remove segment only if it holds no fifos and not the first */
	if (sm->segment_indices[0] != svm_segment_index
	&& !svm_fifo_segment_has_fifos (fifo_segment))
	{
	clib_spinlock_lock (&sm->lockp);
	svm_fifo_segment_delete (fifo_segment);
	vec_del1 (sm->segment_indices, svm_segment_index);
	clib_spinlock_unlock (&sm->lockp);
	}
	}

	/**
	* Allocates shm queue in the first segment
	*/
	unix_shared_memory_queue_t *
	segment_manager_alloc_queue (segment_manager_t * sm, u32 queue_size)
	{
	ssvm_shared_header_t *sh;
	svm_fifo_segment_private_t *segment;
	unix_shared_memory_queue_t *q;
	void *oldheap;

	ASSERT (sm->segment_indices != 0);

	segment = svm_fifo_get_segment (sm->segment_indices[0]);
	sh = segment->ssvm.sh;

	oldheap = ssvm_push_heap (sh);
	q =
	unix_shared_memory_queue_init (queue_size, sizeof (session_fifo_event_t),
	0 /* consumer pid */ , 0
	/* signal when queue non-empty */ );
	ssvm_pop_heap (oldheap);
	return q;
	}

	/**
	* Frees shm queue allocated in the first segment
	*/
	void
	segment_manager_dealloc_queue (segment_manager_t * sm,
	unix_shared_memory_queue_t * q)
	{
	ssvm_shared_header_t *sh;
	svm_fifo_segment_private_t *segment;
	void *oldheap;

	ASSERT (sm->segment_indices != 0);

	segment = svm_fifo_get_segment (sm->segment_indices[0]);
	sh = segment->ssvm.sh;

	oldheap = ssvm_push_heap (sh);
	unix_shared_memory_queue_free (q);
	ssvm_pop_heap (oldheap);
	}

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