src/svm/svm_fifo_segment.c - fdio/vpp - Gitiles

 /*
  * Copyright (c) 2016 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 <svm/svm_fifo_segment.h>

 svm_fifo_segment_main_t svm_fifo_segment_main;

 static void
 allocate_new_fifo_chunk (svm_fifo_segment_header_t * fsh,
 			 u32 data_size_in_bytes, int chunk_size)
 {
   int freelist_index;
   u32 size;
   u8 *fifo_space;
   u32 rounded_data_size;
   svm_fifo_t *f;
   int i;

   rounded_data_size = (1 << (max_log2 (data_size_in_bytes)));
   freelist_index = max_log2 (rounded_data_size)
     - max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);

   /* Calculate space requirement $$$ round-up data_size_in_bytes */
   size = (sizeof (*f) + rounded_data_size) * chunk_size;

   /* Allocate fifo space. May fail. */
   fifo_space = clib_mem_alloc_aligned_at_offset
     (size, CLIB_CACHE_LINE_BYTES, 0 /* align_offset */ ,
      0 /* os_out_of_memory */ );

   /* Out of space.. */
   if (fifo_space == 0)
     return;

   /* Carve fifo space */
   f = (svm_fifo_t *) fifo_space;
   for (i = 0; i < chunk_size; i++)
     {
       f->freelist_index = freelist_index;
       f->next = fsh->free_fifos[freelist_index];
       fsh->free_fifos[freelist_index] = f;
       fifo_space += sizeof (*f) + rounded_data_size;
       f = (svm_fifo_t *) fifo_space;
     }
 }

 static void
 preallocate_fifo_pairs (svm_fifo_segment_header_t * fsh,
 			svm_fifo_segment_create_args_t * a)
 {
   u32 rx_fifo_size, tx_fifo_size;
   u32 rx_rounded_data_size, tx_rounded_data_size;
   svm_fifo_t *f;
   u8 *rx_fifo_space, *tx_fifo_space;
   int rx_freelist_index, tx_freelist_index;
   int i;

   /* Parameter check */
   if (a->rx_fifo_size == 0 || a->tx_fifo_size == 0
       || a->preallocated_fifo_pairs == 0)
     return;

   if (a->rx_fifo_size < FIFO_SEGMENT_MIN_FIFO_SIZE ||
       a->rx_fifo_size > FIFO_SEGMENT_MAX_FIFO_SIZE)
     {
       clib_warning ("rx fifo_size out of range %d", a->rx_fifo_size);
       return;
     }

   if (a->tx_fifo_size < FIFO_SEGMENT_MIN_FIFO_SIZE ||
       a->tx_fifo_size > FIFO_SEGMENT_MAX_FIFO_SIZE)
     {
       clib_warning ("tx fifo_size out of range %d", a->rx_fifo_size);
       return;
     }

   rx_rounded_data_size = (1 << (max_log2 (a->rx_fifo_size)));

   rx_freelist_index = max_log2 (a->rx_fifo_size)
     - max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);

   tx_rounded_data_size = (1 << (max_log2 (a->rx_fifo_size)));

   tx_freelist_index = max_log2 (a->tx_fifo_size)
     - max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);

   /* Calculate space requirements */
   rx_fifo_size = (sizeof (*f) + rx_rounded_data_size)
     * a->preallocated_fifo_pairs;
   tx_fifo_size = (sizeof (*f) + tx_rounded_data_size)
     * a->preallocated_fifo_pairs;

   vec_validate_init_empty (fsh->free_fifos,
 			   clib_max (rx_freelist_index, tx_freelist_index),
 			   0);
   if (0)
     clib_warning ("rx_fifo_size %u (%d mb), tx_fifo_size %u (%d mb)",
 		  rx_fifo_size, rx_fifo_size >> 20,
 		  tx_fifo_size, tx_fifo_size >> 20);

   /* Allocate rx fifo space. May fail. */
   rx_fifo_space = clib_mem_alloc_aligned_at_offset
     (rx_fifo_size, CLIB_CACHE_LINE_BYTES, 0 /* align_offset */ ,
      0 /* os_out_of_memory */ );

   /* Same for TX */
   tx_fifo_space = clib_mem_alloc_aligned_at_offset
     (tx_fifo_size, CLIB_CACHE_LINE_BYTES, 0 /* align_offset */ ,
      0 /* os_out_of_memory */ );

   /* Make sure it worked. Clean up if it didn't... */
   if (rx_fifo_space == 0 || tx_fifo_space == 0)
     {
       if (rx_fifo_space)
 	clib_mem_free (rx_fifo_space);
       else
 	clib_warning ("rx fifo preallocation failure: size %d npairs %d",
 		      a->rx_fifo_size, a->preallocated_fifo_pairs);

       if (tx_fifo_space)
 	clib_mem_free (tx_fifo_space);
       else
 	clib_warning ("tx fifo preallocation failure: size %d nfifos %d",
 		      a->tx_fifo_size, a->preallocated_fifo_pairs);
       return;
     }

   /* Carve rx fifo space */
   f = (svm_fifo_t *) rx_fifo_space;
   for (i = 0; i < a->preallocated_fifo_pairs; i++)
     {
       f->freelist_index = rx_freelist_index;
       f->next = fsh->free_fifos[rx_freelist_index];
       fsh->free_fifos[rx_freelist_index] = f;
       rx_fifo_space += sizeof (*f) + rx_rounded_data_size;
       f = (svm_fifo_t *) rx_fifo_space;
     }
   /* Carve tx fifo space */
   f = (svm_fifo_t *) tx_fifo_space;
   for (i = 0; i < a->preallocated_fifo_pairs; i++)
     {
       f->freelist_index = tx_freelist_index;
       f->next = fsh->free_fifos[tx_freelist_index];
       fsh->free_fifos[tx_freelist_index] = f;
       tx_fifo_space += sizeof (*f) + tx_rounded_data_size;
       f = (svm_fifo_t *) tx_fifo_space;
     }
 }

 /** (master) create an svm fifo segment */
 int
 svm_fifo_segment_create (svm_fifo_segment_create_args_t * a)
 {
   int rv;
   svm_fifo_segment_private_t *s;
   svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
   ssvm_shared_header_t *sh;
   svm_fifo_segment_header_t *fsh;
   void *oldheap;

   /* Allocate a fresh segment */
   pool_get (sm->segments, s);
   memset (s, 0, sizeof (*s));

   s->ssvm.ssvm_size = a->segment_size;
   s->ssvm.i_am_master = 1;
   s->ssvm.my_pid = getpid ();
   s->ssvm.name = format (0, "%s%c", a->segment_name, 0);
   s->ssvm.requested_va = sm->next_baseva;

   rv = ssvm_master_init (&s->ssvm, s - sm->segments);

   if (rv)
     {
       _vec_len (s) = vec_len (s) - 1;
       return (rv);
     }

   /* Note; requested_va updated due to seg base addr randomization */
   sm->next_baseva = s->ssvm.requested_va + a->segment_size;

   sh = s->ssvm.sh;
   oldheap = ssvm_push_heap (sh);

   /* Set up svm_fifo_segment shared header */
   fsh = clib_mem_alloc (sizeof (*fsh));
   memset (fsh, 0, sizeof (*fsh));
   sh->opaque[0] = fsh;
   s->h = fsh;
   fsh->segment_name = format (0, "%s%c", a->segment_name, 0);

   preallocate_fifo_pairs (fsh, a);

   ssvm_pop_heap (oldheap);

   sh->ready = 1;
   vec_add1 (a->new_segment_indices, s - sm->segments);
   return (0);
 }

 /** Create an svm fifo segment in process-private memory */
 int
 svm_fifo_segment_create_process_private (svm_fifo_segment_create_args_t * a)
 {
   svm_fifo_segment_private_t *s;
   svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
   ssvm_shared_header_t *sh;
   svm_fifo_segment_header_t *fsh;
   void *oldheap;
   u8 **heaps = 0;
   mheap_t *heap_header;
   int segment_count = 1;
   int i;

   if (a->private_segment_count && a->private_segment_size)
     {
       void *mem;
       u8 *heap;
       u32 pagesize = clib_mem_get_page_size ();
       u32 rnd_size;

       for (i = 0; i < a->private_segment_count; i++)
 	{
 	  rnd_size = (a->private_segment_size + (pagesize - 1)) & ~pagesize;

 	  mem = mmap (0, rnd_size, PROT_READ | PROT_WRITE,
 		      MAP_PRIVATE | MAP_ANONYMOUS,
 		      -1 /* fd */ , 0 /* offset */ );

 	  if (mem == MAP_FAILED)
 	    {
 	      clib_unix_warning ("mmap");
 	      return -1;
 	    }
 	  heap = mheap_alloc (mem, rnd_size);
 	  heap_header = mheap_header (heap);
 	  heap_header->flags |= MHEAP_FLAG_THREAD_SAFE;
 	  vec_add1 (heaps, heap);
 	}
       segment_count = a->private_segment_count;
     }

   /* Spread preallocated fifo pairs across segments */
   a->preallocated_fifo_pairs /= segment_count;

   /* Allocate segments */
   for (i = 0; i < segment_count; i++)
     {
       pool_get (sm->segments, s);
       memset (s, 0, sizeof (*s));

       s->ssvm.ssvm_size = ~0;
       s->ssvm.i_am_master = 1;
       s->ssvm.my_pid = getpid ();
       s->ssvm.name = format (0, "%s%c", a->segment_name, 0);
       s->ssvm.requested_va = ~0;

       /* Allocate a [sic] shared memory header, in process memory... */
       sh = clib_mem_alloc_aligned (sizeof (*sh), CLIB_CACHE_LINE_BYTES);
       s->ssvm.sh = sh;

       memset (sh, 0, sizeof (*sh));
       sh->heap = a->private_segment_count ? heaps[i] : clib_mem_get_heap ();

       /* Set up svm_fifo_segment shared header */
       fsh = clib_mem_alloc (sizeof (*fsh));
       memset (fsh, 0, sizeof (*fsh));
       sh->opaque[0] = fsh;
       s->h = fsh;
       fsh->segment_name = format (0, "%s%c", a->segment_name, 0);

       if (a->private_segment_count)
 	{
 	  oldheap = clib_mem_get_heap ();
 	  clib_mem_set_heap (sh->heap);
 	  preallocate_fifo_pairs (fsh, a);
 	  clib_mem_set_heap (oldheap);
 	}

       sh->ready = 1;
       vec_add1 (a->new_segment_indices, s - sm->segments);
     }
   vec_free (heaps);
   return (0);
 }

 /** (slave) attach to an svm fifo segment */
 int
 svm_fifo_segment_attach (svm_fifo_segment_create_args_t * a)
 {
   int rv;
   svm_fifo_segment_private_t *s;
   svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
   ssvm_shared_header_t *sh;
   svm_fifo_segment_header_t *fsh;

   /* Allocate a fresh segment */
   pool_get (sm->segments, s);
   memset (s, 0, sizeof (*s));

   s->ssvm.ssvm_size = a->segment_size;
   s->ssvm.my_pid = getpid ();
   s->ssvm.name = format (0, "%s%c", a->segment_name, 0);
   s->ssvm.requested_va = sm->next_baseva;

   rv = ssvm_slave_init (&s->ssvm, sm->timeout_in_seconds);

   if (rv)
     {
       _vec_len (s) = vec_len (s) - 1;
       return (rv);
     }

   /* Fish the segment header */
   sh = s->ssvm.sh;
   fsh = (svm_fifo_segment_header_t *) sh->opaque[0];
   s->h = fsh;

   vec_add1 (a->new_segment_indices, s - sm->segments);
   return (0);
 }

 void
 svm_fifo_segment_delete (svm_fifo_segment_private_t * s)
 {
   svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
   ssvm_delete (&s->ssvm);
   pool_put (sm->segments, s);
 }

 svm_fifo_t *
 svm_fifo_segment_alloc_fifo (svm_fifo_segment_private_t * s,
 			     u32 data_size_in_bytes,
 			     svm_fifo_segment_freelist_t list_index)
 {
   ssvm_shared_header_t *sh;
   svm_fifo_segment_header_t *fsh;
   svm_fifo_t *f;
   void *oldheap;
   int freelist_index;

   /*
    * 2K minimum. It's not likely that anything good will happen
    * with a 1K FIFO.
    */
   if (data_size_in_bytes < FIFO_SEGMENT_MIN_FIFO_SIZE ||
       data_size_in_bytes > FIFO_SEGMENT_MAX_FIFO_SIZE)
     {
       clib_warning ("fifo size out of range %d", data_size_in_bytes);
       return 0;
     }

   freelist_index = max_log2 (data_size_in_bytes)
     - max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);

   sh = s->ssvm.sh;
   fsh = (svm_fifo_segment_header_t *) sh->opaque[0];

   ssvm_lock_non_recursive (sh, 1);
   oldheap = ssvm_push_heap (sh);

   switch (list_index)
     {
     case FIFO_SEGMENT_RX_FREELIST:
     case FIFO_SEGMENT_TX_FREELIST:
       vec_validate_init_empty (fsh->free_fifos, freelist_index, 0);

       f = fsh->free_fifos[freelist_index];
       if (PREDICT_FALSE (f == 0))
 	{
 	  allocate_new_fifo_chunk (fsh, data_size_in_bytes,
 				   FIFO_SEGMENT_ALLOC_CHUNK_SIZE);
 	  f = fsh->free_fifos[freelist_index];
 	}
       if (PREDICT_TRUE (f != 0))
 	{
 	  fsh->free_fifos[freelist_index] = f->next;
 	  /* (re)initialize the fifo, as in svm_fifo_create */
 	  memset (f, 0, sizeof (*f));
 	  f->nitems = data_size_in_bytes;
 	  f->ooos_list_head = OOO_SEGMENT_INVALID_INDEX;
 	  f->refcnt = 1;
 	  f->freelist_index = freelist_index;
 	  goto found;
 	}
       /* FALLTHROUGH */
     case FIFO_SEGMENT_FREELIST_NONE:
       break;

     default:
       clib_warning ("ignore bogus freelist %d", list_index);
       break;
     }

   /* Note: this can fail, in which case: create another segment */
   f = svm_fifo_create (data_size_in_bytes);
   if (PREDICT_FALSE (f == 0))
     {
       ssvm_pop_heap (oldheap);
       ssvm_unlock_non_recursive (sh);
       return (0);
     }
   f->freelist_index = freelist_index;

 found:
   /* If rx_freelist add to active fifos list. When cleaning up segment,
    * we need a list of active sessions that should be disconnected. Since
    * both rx and tx fifos keep pointers to the session, it's enough to track
    * only one. */
   if (list_index == FIFO_SEGMENT_RX_FREELIST)
     {
       if (fsh->fifos)
 	{
 	  fsh->fifos->prev = f;
 	  f->next = fsh->fifos;
 	}
       fsh->fifos = f;
     }

   ssvm_pop_heap (oldheap);
   ssvm_unlock_non_recursive (sh);
   return (f);
 }

 void
 svm_fifo_segment_free_fifo (svm_fifo_segment_private_t * s, svm_fifo_t * f,
 			    svm_fifo_segment_freelist_t list_index)
 {
   ssvm_shared_header_t *sh;
   svm_fifo_segment_header_t *fsh;
   void *oldheap;
   int freelist_index;

   ASSERT (f->refcnt > 0);

   if (--f->refcnt > 0)
     return;

   sh = s->ssvm.sh;
   fsh = (svm_fifo_segment_header_t *) sh->opaque[0];

   freelist_index = f->freelist_index;

   ASSERT (freelist_index > 0 && freelist_index < vec_len (fsh->free_fifos));

   ssvm_lock_non_recursive (sh, 2);
   oldheap = ssvm_push_heap (sh);

   switch (list_index)
     {
     case FIFO_SEGMENT_RX_FREELIST:
       /* Remove from active list */
       if (f->prev)
 	f->prev->next = f->next;
       else
 	fsh->fifos = f->next;
       if (f->next)
 	f->next->prev = f->prev;
       /* Fall through: we add only rx fifos to active pool */
     case FIFO_SEGMENT_TX_FREELIST:
       /* Add to free list */
       f->next = fsh->free_fifos[freelist_index];
       f->prev = 0;
       fsh->free_fifos[freelist_index] = f;
       break;
     case FIFO_SEGMENT_FREELIST_NONE:
       break;

     default:
       clib_warning ("ignore bogus freelist %d", list_index);
       break;
     }

   if (CLIB_DEBUG)
     {
       f->master_session_index = ~0;
       f->master_thread_index = ~0;
     }

   ssvm_pop_heap (oldheap);
   ssvm_unlock_non_recursive (sh);
 }

 void
 svm_fifo_segment_init (u64 baseva, u32 timeout_in_seconds)
 {
   svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;

   sm->next_baseva = baseva;
   sm->timeout_in_seconds = timeout_in_seconds;
 }

 u32
 svm_fifo_segment_index (svm_fifo_segment_private_t * s)
 {
   return s - svm_fifo_segment_main.segments;
 }

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	* Copyright (c) 2016 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 <svm/svm_fifo_segment.h>

	svm_fifo_segment_main_t svm_fifo_segment_main;

	static void
	allocate_new_fifo_chunk (svm_fifo_segment_header_t * fsh,
	u32 data_size_in_bytes, int chunk_size)
	{
	int freelist_index;
	u32 size;
	u8 *fifo_space;
	u32 rounded_data_size;
	svm_fifo_t *f;
	int i;

	rounded_data_size = (1 << (max_log2 (data_size_in_bytes)));
	freelist_index = max_log2 (rounded_data_size)
	- max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);

	/* Calculate space requirement $$$ round-up data_size_in_bytes */
	size = (sizeof (f) + rounded_data_size) chunk_size;

	/* Allocate fifo space. May fail. */
	fifo_space = clib_mem_alloc_aligned_at_offset
	(size, CLIB_CACHE_LINE_BYTES, 0 /* align_offset */ ,
	0 /* os_out_of_memory */ );

	/* Out of space.. */
	if (fifo_space == 0)
	return;

	/* Carve fifo space */
	f = (svm_fifo_t *) fifo_space;
	for (i = 0; i < chunk_size; i++)
	{
	f->freelist_index = freelist_index;
	f->next = fsh->free_fifos[freelist_index];
	fsh->free_fifos[freelist_index] = f;
	fifo_space += sizeof (*f) + rounded_data_size;
	f = (svm_fifo_t *) fifo_space;
	}
	}

	static void
	preallocate_fifo_pairs (svm_fifo_segment_header_t * fsh,
	svm_fifo_segment_create_args_t * a)
	{
	u32 rx_fifo_size, tx_fifo_size;
	u32 rx_rounded_data_size, tx_rounded_data_size;
	svm_fifo_t *f;
	u8 rx_fifo_space, tx_fifo_space;
	int rx_freelist_index, tx_freelist_index;
	int i;

	/* Parameter check */
	if (a->rx_fifo_size == 0 \|\| a->tx_fifo_size == 0
	\|\| a->preallocated_fifo_pairs == 0)
	return;

	if (a->rx_fifo_size < FIFO_SEGMENT_MIN_FIFO_SIZE \|\|
	a->rx_fifo_size > FIFO_SEGMENT_MAX_FIFO_SIZE)
	{
	clib_warning ("rx fifo_size out of range %d", a->rx_fifo_size);
	return;
	}

	if (a->tx_fifo_size < FIFO_SEGMENT_MIN_FIFO_SIZE \|\|
	a->tx_fifo_size > FIFO_SEGMENT_MAX_FIFO_SIZE)
	{
	clib_warning ("tx fifo_size out of range %d", a->rx_fifo_size);
	return;
	}

	rx_rounded_data_size = (1 << (max_log2 (a->rx_fifo_size)));

	rx_freelist_index = max_log2 (a->rx_fifo_size)
	- max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);

	tx_rounded_data_size = (1 << (max_log2 (a->rx_fifo_size)));

	tx_freelist_index = max_log2 (a->tx_fifo_size)
	- max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);

	/* Calculate space requirements */
	rx_fifo_size = (sizeof (*f) + rx_rounded_data_size)
	* a->preallocated_fifo_pairs;
	tx_fifo_size = (sizeof (*f) + tx_rounded_data_size)
	* a->preallocated_fifo_pairs;

	vec_validate_init_empty (fsh->free_fifos,
	clib_max (rx_freelist_index, tx_freelist_index),
	0);
	if (0)
	clib_warning ("rx_fifo_size %u (%d mb), tx_fifo_size %u (%d mb)",
	rx_fifo_size, rx_fifo_size >> 20,
	tx_fifo_size, tx_fifo_size >> 20);

	/* Allocate rx fifo space. May fail. */
	rx_fifo_space = clib_mem_alloc_aligned_at_offset
	(rx_fifo_size, CLIB_CACHE_LINE_BYTES, 0 /* align_offset */ ,
	0 /* os_out_of_memory */ );

	/* Same for TX */
	tx_fifo_space = clib_mem_alloc_aligned_at_offset
	(tx_fifo_size, CLIB_CACHE_LINE_BYTES, 0 /* align_offset */ ,
	0 /* os_out_of_memory */ );

	/* Make sure it worked. Clean up if it didn't... */
	if (rx_fifo_space == 0 \|\| tx_fifo_space == 0)
	{
	if (rx_fifo_space)
	clib_mem_free (rx_fifo_space);
	else
	clib_warning ("rx fifo preallocation failure: size %d npairs %d",
	a->rx_fifo_size, a->preallocated_fifo_pairs);

	if (tx_fifo_space)
	clib_mem_free (tx_fifo_space);
	else
	clib_warning ("tx fifo preallocation failure: size %d nfifos %d",
	a->tx_fifo_size, a->preallocated_fifo_pairs);
	return;
	}

	/* Carve rx fifo space */
	f = (svm_fifo_t *) rx_fifo_space;
	for (i = 0; i < a->preallocated_fifo_pairs; i++)
	{
	f->freelist_index = rx_freelist_index;
	f->next = fsh->free_fifos[rx_freelist_index];
	fsh->free_fifos[rx_freelist_index] = f;
	rx_fifo_space += sizeof (*f) + rx_rounded_data_size;
	f = (svm_fifo_t *) rx_fifo_space;
	}
	/* Carve tx fifo space */
	f = (svm_fifo_t *) tx_fifo_space;
	for (i = 0; i < a->preallocated_fifo_pairs; i++)
	{
	f->freelist_index = tx_freelist_index;
	f->next = fsh->free_fifos[tx_freelist_index];
	fsh->free_fifos[tx_freelist_index] = f;
	tx_fifo_space += sizeof (*f) + tx_rounded_data_size;
	f = (svm_fifo_t *) tx_fifo_space;
	}
	}

	/** (master) create an svm fifo segment */
	int
	svm_fifo_segment_create (svm_fifo_segment_create_args_t * a)
	{
	int rv;
	svm_fifo_segment_private_t *s;
	svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
	ssvm_shared_header_t *sh;
	svm_fifo_segment_header_t *fsh;
	void *oldheap;

	/* Allocate a fresh segment */
	pool_get (sm->segments, s);
	memset (s, 0, sizeof (*s));

	s->ssvm.ssvm_size = a->segment_size;
	s->ssvm.i_am_master = 1;
	s->ssvm.my_pid = getpid ();
	s->ssvm.name = format (0, "%s%c", a->segment_name, 0);
	s->ssvm.requested_va = sm->next_baseva;

	rv = ssvm_master_init (&s->ssvm, s - sm->segments);

	if (rv)
	{
	_vec_len (s) = vec_len (s) - 1;
	return (rv);
	}

	/* Note; requested_va updated due to seg base addr randomization */
	sm->next_baseva = s->ssvm.requested_va + a->segment_size;

	sh = s->ssvm.sh;
	oldheap = ssvm_push_heap (sh);

	/* Set up svm_fifo_segment shared header */
	fsh = clib_mem_alloc (sizeof (*fsh));
	memset (fsh, 0, sizeof (*fsh));
	sh->opaque[0] = fsh;
	s->h = fsh;
	fsh->segment_name = format (0, "%s%c", a->segment_name, 0);

	preallocate_fifo_pairs (fsh, a);

	ssvm_pop_heap (oldheap);

	sh->ready = 1;
	vec_add1 (a->new_segment_indices, s - sm->segments);
	return (0);
	}

	/** Create an svm fifo segment in process-private memory */
	int
	svm_fifo_segment_create_process_private (svm_fifo_segment_create_args_t * a)
	{
	svm_fifo_segment_private_t *s;
	svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
	ssvm_shared_header_t *sh;
	svm_fifo_segment_header_t *fsh;
	void *oldheap;
	u8 **heaps = 0;
	mheap_t *heap_header;
	int segment_count = 1;
	int i;

	if (a->private_segment_count && a->private_segment_size)
	{
	void *mem;
	u8 *heap;
	u32 pagesize = clib_mem_get_page_size ();
	u32 rnd_size;

	for (i = 0; i < a->private_segment_count; i++)
	{
	rnd_size = (a->private_segment_size + (pagesize - 1)) & ~pagesize;

	mem = mmap (0, rnd_size, PROT_READ \| PROT_WRITE,
	MAP_PRIVATE \| MAP_ANONYMOUS,
	-1 /* fd / , 0 / offset */ );

	if (mem == MAP_FAILED)
	{
	clib_unix_warning ("mmap");
	return -1;
	}
	heap = mheap_alloc (mem, rnd_size);
	heap_header = mheap_header (heap);
	heap_header->flags \|= MHEAP_FLAG_THREAD_SAFE;
	vec_add1 (heaps, heap);
	}
	segment_count = a->private_segment_count;
	}

	/* Spread preallocated fifo pairs across segments */
	a->preallocated_fifo_pairs /= segment_count;

	/* Allocate segments */
	for (i = 0; i < segment_count; i++)
	{
	pool_get (sm->segments, s);
	memset (s, 0, sizeof (*s));

	s->ssvm.ssvm_size = ~0;
	s->ssvm.i_am_master = 1;
	s->ssvm.my_pid = getpid ();
	s->ssvm.name = format (0, "%s%c", a->segment_name, 0);
	s->ssvm.requested_va = ~0;

	/* Allocate a [sic] shared memory header, in process memory... */
	sh = clib_mem_alloc_aligned (sizeof (*sh), CLIB_CACHE_LINE_BYTES);
	s->ssvm.sh = sh;

	memset (sh, 0, sizeof (*sh));
	sh->heap = a->private_segment_count ? heaps[i] : clib_mem_get_heap ();

	/* Set up svm_fifo_segment shared header */
	fsh = clib_mem_alloc (sizeof (*fsh));
	memset (fsh, 0, sizeof (*fsh));
	sh->opaque[0] = fsh;
	s->h = fsh;
	fsh->segment_name = format (0, "%s%c", a->segment_name, 0);

	if (a->private_segment_count)
	{
	oldheap = clib_mem_get_heap ();
	clib_mem_set_heap (sh->heap);
	preallocate_fifo_pairs (fsh, a);
	clib_mem_set_heap (oldheap);
	}

	sh->ready = 1;
	vec_add1 (a->new_segment_indices, s - sm->segments);
	}
	vec_free (heaps);
	return (0);
	}

	/** (slave) attach to an svm fifo segment */
	int
	svm_fifo_segment_attach (svm_fifo_segment_create_args_t * a)
	{
	int rv;
	svm_fifo_segment_private_t *s;
	svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
	ssvm_shared_header_t *sh;
	svm_fifo_segment_header_t *fsh;

	/* Allocate a fresh segment */
	pool_get (sm->segments, s);
	memset (s, 0, sizeof (*s));

	s->ssvm.ssvm_size = a->segment_size;
	s->ssvm.my_pid = getpid ();
	s->ssvm.name = format (0, "%s%c", a->segment_name, 0);
	s->ssvm.requested_va = sm->next_baseva;

	rv = ssvm_slave_init (&s->ssvm, sm->timeout_in_seconds);

	if (rv)
	{
	_vec_len (s) = vec_len (s) - 1;
	return (rv);
	}

	/* Fish the segment header */
	sh = s->ssvm.sh;
	fsh = (svm_fifo_segment_header_t *) sh->opaque[0];
	s->h = fsh;

	vec_add1 (a->new_segment_indices, s - sm->segments);
	return (0);
	}

	void
	svm_fifo_segment_delete (svm_fifo_segment_private_t * s)
	{
	svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;
	ssvm_delete (&s->ssvm);
	pool_put (sm->segments, s);
	}

	svm_fifo_t *
	svm_fifo_segment_alloc_fifo (svm_fifo_segment_private_t * s,
	u32 data_size_in_bytes,
	svm_fifo_segment_freelist_t list_index)
	{
	ssvm_shared_header_t *sh;
	svm_fifo_segment_header_t *fsh;
	svm_fifo_t *f;
	void *oldheap;
	int freelist_index;

	/*
	* 2K minimum. It's not likely that anything good will happen
	* with a 1K FIFO.
	*/
	if (data_size_in_bytes < FIFO_SEGMENT_MIN_FIFO_SIZE \|\|
	data_size_in_bytes > FIFO_SEGMENT_MAX_FIFO_SIZE)
	{
	clib_warning ("fifo size out of range %d", data_size_in_bytes);
	return 0;
	}

	freelist_index = max_log2 (data_size_in_bytes)
	- max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);

	sh = s->ssvm.sh;
	fsh = (svm_fifo_segment_header_t *) sh->opaque[0];

	ssvm_lock_non_recursive (sh, 1);
	oldheap = ssvm_push_heap (sh);

	switch (list_index)
	{
	case FIFO_SEGMENT_RX_FREELIST:
	case FIFO_SEGMENT_TX_FREELIST:
	vec_validate_init_empty (fsh->free_fifos, freelist_index, 0);

	f = fsh->free_fifos[freelist_index];
	if (PREDICT_FALSE (f == 0))
	{
	allocate_new_fifo_chunk (fsh, data_size_in_bytes,
	FIFO_SEGMENT_ALLOC_CHUNK_SIZE);
	f = fsh->free_fifos[freelist_index];
	}
	if (PREDICT_TRUE (f != 0))
	{
	fsh->free_fifos[freelist_index] = f->next;
	/* (re)initialize the fifo, as in svm_fifo_create */
	memset (f, 0, sizeof (*f));
	f->nitems = data_size_in_bytes;
	f->ooos_list_head = OOO_SEGMENT_INVALID_INDEX;
	f->refcnt = 1;
	f->freelist_index = freelist_index;
	goto found;
	}
	/* FALLTHROUGH */
	case FIFO_SEGMENT_FREELIST_NONE:
	break;

	default:
	clib_warning ("ignore bogus freelist %d", list_index);
	break;
	}

	/* Note: this can fail, in which case: create another segment */
	f = svm_fifo_create (data_size_in_bytes);
	if (PREDICT_FALSE (f == 0))
	{
	ssvm_pop_heap (oldheap);
	ssvm_unlock_non_recursive (sh);
	return (0);
	}
	f->freelist_index = freelist_index;

	found:
	/* If rx_freelist add to active fifos list. When cleaning up segment,
	* we need a list of active sessions that should be disconnected. Since
	* both rx and tx fifos keep pointers to the session, it's enough to track
	* only one. */
	if (list_index == FIFO_SEGMENT_RX_FREELIST)
	{
	if (fsh->fifos)
	{
	fsh->fifos->prev = f;
	f->next = fsh->fifos;
	}
	fsh->fifos = f;
	}

	ssvm_pop_heap (oldheap);
	ssvm_unlock_non_recursive (sh);
	return (f);
	}

	void
	svm_fifo_segment_free_fifo (svm_fifo_segment_private_t * s, svm_fifo_t * f,
	svm_fifo_segment_freelist_t list_index)
	{
	ssvm_shared_header_t *sh;
	svm_fifo_segment_header_t *fsh;
	void *oldheap;
	int freelist_index;

	ASSERT (f->refcnt > 0);

	if (--f->refcnt > 0)
	return;

	sh = s->ssvm.sh;
	fsh = (svm_fifo_segment_header_t *) sh->opaque[0];

	freelist_index = f->freelist_index;

	ASSERT (freelist_index > 0 && freelist_index < vec_len (fsh->free_fifos));

	ssvm_lock_non_recursive (sh, 2);
	oldheap = ssvm_push_heap (sh);

	switch (list_index)
	{
	case FIFO_SEGMENT_RX_FREELIST:
	/* Remove from active list */
	if (f->prev)
	f->prev->next = f->next;
	else
	fsh->fifos = f->next;
	if (f->next)
	f->next->prev = f->prev;
	/* Fall through: we add only rx fifos to active pool */
	case FIFO_SEGMENT_TX_FREELIST:
	/* Add to free list */
	f->next = fsh->free_fifos[freelist_index];
	f->prev = 0;
	fsh->free_fifos[freelist_index] = f;
	break;
	case FIFO_SEGMENT_FREELIST_NONE:
	break;

	default:
	clib_warning ("ignore bogus freelist %d", list_index);
	break;
	}

	if (CLIB_DEBUG)
	{
	f->master_session_index = ~0;
	f->master_thread_index = ~0;
	}

	ssvm_pop_heap (oldheap);
	ssvm_unlock_non_recursive (sh);
	}

	void
	svm_fifo_segment_init (u64 baseva, u32 timeout_in_seconds)
	{
	svm_fifo_segment_main_t *sm = &svm_fifo_segment_main;

	sm->next_baseva = baseva;
	sm->timeout_in_seconds = timeout_in_seconds;
	}

	u32
	svm_fifo_segment_index (svm_fifo_segment_private_t * s)
	{
	return s - svm_fifo_segment_main.segments;
	}

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