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>

 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;
     }
 }

 /**
  * Pre-allocates fifo pairs in fifo segment
  *
  * The number of fifos pre-allocated is the minimum of the requested number
  * of pairs and the maximum number that fit within the segment. If the maximum
  * is hit, the number of fifo pairs requested is updated by subtracting the
  * number of fifos that have been successfully allocated.
  */
 void
 svm_fifo_segment_preallocate_fifo_pairs (svm_fifo_segment_private_t * s,
 					 u32 rx_fifo_size, u32 tx_fifo_size,
 					 u32 * n_fifo_pairs)
 {
   u32 rx_rounded_data_size, tx_rounded_data_size, pair_size;
   u32 rx_fifos_size, tx_fifos_size, pairs_to_allocate;
   int rx_freelist_index, tx_freelist_index;
   ssvm_shared_header_t *sh = s->ssvm.sh;
   svm_fifo_segment_header_t *fsh = s->h;
   u8 *rx_fifo_space, *tx_fifo_space;
   uword space_available;
   void *oldheap;
   svm_fifo_t *f;
   int i;

   /* Parameter check */
   if (rx_fifo_size == 0 || tx_fifo_size == 0 || *n_fifo_pairs == 0)
     return;

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

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

   rx_rounded_data_size = (1 << (max_log2 (rx_fifo_size)));
   rx_freelist_index = max_log2 (rx_fifo_size)
     - max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);
   tx_rounded_data_size = (1 << (max_log2 (tx_fifo_size)));
   tx_freelist_index = max_log2 (tx_fifo_size)
     - max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);

   /* Calculate space requirements */
   pair_size = 2 * sizeof (*f) + rx_rounded_data_size + tx_rounded_data_size;
 #if USE_DLMALLOC == 0
   space_available = s->ssvm.ssvm_size - mheap_bytes (sh->heap);
 #else
   space_available = s->ssvm.ssvm_size - mspace_usable_size (sh->heap);
 #endif

   pairs_to_allocate = clib_min (space_available / pair_size, *n_fifo_pairs);
   rx_fifos_size = (sizeof (*f) + rx_rounded_data_size) * pairs_to_allocate;
   tx_fifos_size = (sizeof (*f) + tx_rounded_data_size) * pairs_to_allocate;

   vec_validate_init_empty (fsh->free_fifos,
 			   clib_max (rx_freelist_index, tx_freelist_index),
 			   0);

   oldheap = ssvm_push_heap (sh);
   /* Allocate rx fifo space. May fail. */
   rx_fifo_space = clib_mem_alloc_aligned_at_offset
     (rx_fifos_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_fifos_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",
 		      rx_fifo_size, *n_fifo_pairs);

       if (tx_fifo_space)
 	clib_mem_free (tx_fifo_space);
       else
 	clib_warning ("tx fifo preallocation failure: size %d nfifos %d",
 		      tx_fifo_size, *n_fifo_pairs);
       ssvm_pop_heap (oldheap);
       return;
     }

   /* Carve rx fifo space */
   f = (svm_fifo_t *) rx_fifo_space;
   for (i = 0; i < pairs_to_allocate; 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 < pairs_to_allocate; 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;
     }

   /* Account for the pairs allocated */
   *n_fifo_pairs -= pairs_to_allocate;
   ssvm_pop_heap (oldheap);
 }

 /**
  * Initialize svm fifo segment shared header
  */
 int
 svm_fifo_segment_init (svm_fifo_segment_private_t * s)
 {
   svm_fifo_segment_header_t *fsh;
   ssvm_shared_header_t *sh;
   void *oldheap;

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

   fsh = clib_mem_alloc (sizeof (*fsh));
   clib_memset (fsh, 0, sizeof (*fsh));
   s->h = sh->opaque[0] = fsh;

   ssvm_pop_heap (oldheap);

   sh->ready = 1;
   return (0);
 }

 /**
  * Create an svm fifo segment and initialize as master
  */
 int
 svm_fifo_segment_create (svm_fifo_segment_main_t * sm,
 			 svm_fifo_segment_create_args_t * a)
 {
   svm_fifo_segment_private_t *s;
   int rv;

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

   if ((rv = ssvm_master_init (&s->ssvm, a->segment_type)))
     {
       pool_put (sm->segments, s);
       return (rv);
     }

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

   svm_fifo_segment_init (s);
   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_main_t * sm,
 					 svm_fifo_segment_create_args_t * a)
 {
   svm_fifo_segment_private_t *s;
   ssvm_shared_header_t *sh;
   u32 rnd_size = 0;
   u8 *heap;
   u32 pagesize = clib_mem_get_page_size ();

   pool_get (sm->segments, s);
   clib_memset (s, 0, sizeof (*s));

   rnd_size = (a->segment_size + (pagesize - 1)) & ~pagesize;

 #if USE_DLMALLOC == 0
   heap = mheap_alloc (0, rnd_size);
   if (heap == 0)
     {
       clib_unix_warning ("mheap alloc");
       pool_put (sm->segments, s);
       return -1;
     }
   {
     mheap_t *heap_header;
     heap_header = mheap_header (heap);
     heap_header->flags |= MHEAP_FLAG_THREAD_SAFE;
   }
 #else
   heap = create_mspace (rnd_size, 1 /* locked */ );
 #endif

   s->ssvm.ssvm_size = rnd_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 = ~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;

   clib_memset (sh, 0, sizeof (*sh));
   sh->heap = heap;

   svm_fifo_segment_init (s);
   vec_add1 (a->new_segment_indices, s - sm->segments);

   return (0);
 }

 /**
  * Attach as slave to an svm fifo segment
  */
 int
 svm_fifo_segment_attach (svm_fifo_segment_main_t * sm,
 			 svm_fifo_segment_create_args_t * a)
 {
   svm_fifo_segment_private_t *s;
   int rv;

   /* Allocate a fresh segment */
   pool_get (sm->segments, s);
   clib_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;
   if (a->segment_type == SSVM_SEGMENT_MEMFD)
     s->ssvm.fd = a->memfd_fd;
   else
     s->ssvm.attach_timeout = sm->timeout_in_seconds;

   if ((rv = ssvm_slave_init (&s->ssvm, a->segment_type)))
     {
       _vec_len (s) = vec_len (s) - 1;
       return (rv);
     }

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

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

 void
 svm_fifo_segment_delete (svm_fifo_segment_main_t * sm,
 			 svm_fifo_segment_private_t * s)
 {
   ssvm_delete (&s->ssvm);
   clib_memset (s, 0xfe, sizeof (*s));
   pool_put (sm->segments, s);
 }

 /**
  * Allocate fifo in svm segment
  */
 svm_fifo_t *
 svm_fifo_segment_alloc_fifo (svm_fifo_segment_private_t * fs,
 			     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 = 0;
   void *oldheap;
   int freelist_index;

   /*
    * 4K minimum. It's not likely that anything good will happen
    * with a smaller 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 = fs->ssvm.sh;
   ssvm_lock_non_recursive (sh, 1);
   fsh = (svm_fifo_segment_header_t *) sh->opaque[0];

   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))
 	{
 	  /* Preallocated and no fifo left. Don't even try */
 	  if (fsh->flags & FIFO_SEGMENT_F_IS_PREALLOCATED)
 	    goto done;

 	  oldheap = ssvm_push_heap (sh);
 	  allocate_new_fifo_chunk (fsh, data_size_in_bytes,
 				   FIFO_SEGMENT_ALLOC_CHUNK_SIZE);
 	  ssvm_pop_heap (oldheap);
 	  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 */
 	  clib_memset (f, 0, sizeof (*f));
 	  f->nitems = data_size_in_bytes;
 	  f->ooos_list_head = OOO_SEGMENT_INVALID_INDEX;
 	  f->ct_session_index = SVM_FIFO_INVALID_SESSION_INDEX;
 	  f->refcnt = 1;
 	  f->freelist_index = freelist_index;
 	  goto found;
 	}
       break;
     case FIFO_SEGMENT_FREELIST_NONE:
       break;

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

   /* Catch all that allocates just one fifo. Note: this can fail,
    * in which case: create another segment */
   oldheap = ssvm_push_heap (sh);
   f = svm_fifo_create (data_size_in_bytes);
   ssvm_pop_heap (oldheap);
   if (PREDICT_FALSE (f == 0))
     goto done;
   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;
     }
   fsh->n_active_fifos++;

 done:
   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 < 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;
     }

   fsh->n_active_fifos--;
   ssvm_pop_heap (oldheap);
   ssvm_unlock_non_recursive (sh);
 }

 void
 svm_fifo_segment_main_init (svm_fifo_segment_main_t * sm, u64 baseva,
 			    u32 timeout_in_seconds)
 {
   sm->next_baseva = baseva;
   sm->timeout_in_seconds = timeout_in_seconds;
 }

 u32
 svm_fifo_segment_index (svm_fifo_segment_main_t * sm,
 			svm_fifo_segment_private_t * s)
 {
   return s - sm->segments;
 }

 /**
  * Retrieve svm segments pool. Used only for debug purposes.
  */
 svm_fifo_segment_private_t *
 svm_fifo_segment_segments_pool (svm_fifo_segment_main_t * sm)
 {
   return sm->segments;
 }

 /**
  * Get number of active fifos
  */
 u32
 svm_fifo_segment_num_fifos (svm_fifo_segment_private_t * fifo_segment)
 {
   return fifo_segment->h->n_active_fifos;
 }

 u32
 svm_fifo_segment_num_free_fifos (svm_fifo_segment_private_t * fifo_segment,
 				 u32 fifo_size_in_bytes)
 {
   ssvm_shared_header_t *sh;
   svm_fifo_segment_header_t *fsh;
   svm_fifo_t *f;
   int i;
   u32 count = 0, rounded_data_size, freelist_index;

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

   /* Count all free fifos? */
   if (fifo_size_in_bytes == ~0)
     {
       for (i = 0; i < vec_len (fsh->free_fifos); i++)
 	{
 	  f = fsh->free_fifos[i];
 	  if (f == 0)
 	    continue;

 	  while (f)
 	    {
 	      f = f->next;
 	      count++;
 	    }
 	}
       return count;
     }

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

   if (freelist_index >= vec_len (fsh->free_fifos))
     return 0;

   f = fsh->free_fifos[freelist_index];
   if (f == 0)
     return 0;

   while (f)
     {
       f = f->next;
       count++;
     }
   return count;
 }

 void
 svm_fifo_segment_info (svm_fifo_segment_private_t * seg, char **address,
 		       size_t * size)
 {
   if (ssvm_type (&seg->ssvm) == SSVM_SEGMENT_PRIVATE)
     {
 #if USE_DLMALLOC == 0
       mheap_t *heap_header;

       *address = pointer_to_uword (seg->ssvm.sh->heap);
       heap_header = mheap_header (seg->ssvm.sh->heap);
       *size = heap_header->max_size;
 #else
       mspace_get_address_and_size (seg->ssvm.sh->heap, address, size);
 #endif
     }
   else
     {
       *address = (char *) seg->ssvm.sh->ssvm_va;
       *size = seg->ssvm.ssvm_size;
     }
 }

 void *
 svm_fifo_segment_heap (svm_fifo_segment_private_t * seg)
 {
   return seg->ssvm.sh->heap;
 }

 u8 *
 format_svm_fifo_segment_type (u8 * s, va_list * args)
 {
   svm_fifo_segment_private_t *sp;
   sp = va_arg (*args, svm_fifo_segment_private_t *);
   ssvm_segment_type_t st = ssvm_type (&sp->ssvm);

   if (st == SSVM_SEGMENT_PRIVATE)
     s = format (s, "%s", "private-heap");
   else if (st == SSVM_SEGMENT_MEMFD)
     s = format (s, "%s", "memfd");
   else if (st == SSVM_SEGMENT_SHM)
     s = format (s, "%s", "shm");
   else
     s = format (s, "%s", "unknown");
   return s;
 }

 /**
  * Segment format function
  */
 u8 *
 format_svm_fifo_segment (u8 * s, va_list * args)
 {
   svm_fifo_segment_private_t *sp
     = va_arg (*args, svm_fifo_segment_private_t *);
   int verbose __attribute__ ((unused)) = va_arg (*args, int);
   svm_fifo_segment_header_t *fsh = sp->h;
   u32 count, indent;
   svm_fifo_t *f;
   int i;

   indent = format_get_indent (s) + 2;
 #if USE_DLMALLOC == 0
   s = format (s, "%U segment heap: %U\n", format_white_space, indent,
 	      format_mheap, svm_fifo_segment_heap (sp), verbose);
   s = format (s, "%U segment has %u active fifos\n",
 	      format_white_space, indent, svm_fifo_segment_num_fifos (sp));
 #endif

   for (i = 0; i < vec_len (fsh->free_fifos); i++)
     {
       f = fsh->free_fifos[i];
       if (f == 0)
 	continue;
       count = 0;
       while (f)
 	{
 	  f = f->next;
 	  count++;
 	}

       s = format (s, "%U%-5u Kb: %u free",
 		  format_white_space, indent + 2,
 		  1 << (i + max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE) - 10),
 		  count);
     }
   return s;
 }

 /*
  * 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>

	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;
	}
	}

	/**
	* Pre-allocates fifo pairs in fifo segment
	*
	* The number of fifos pre-allocated is the minimum of the requested number
	* of pairs and the maximum number that fit within the segment. If the maximum
	* is hit, the number of fifo pairs requested is updated by subtracting the
	* number of fifos that have been successfully allocated.
	*/
	void
	svm_fifo_segment_preallocate_fifo_pairs (svm_fifo_segment_private_t * s,
	u32 rx_fifo_size, u32 tx_fifo_size,
	u32 * n_fifo_pairs)
	{
	u32 rx_rounded_data_size, tx_rounded_data_size, pair_size;
	u32 rx_fifos_size, tx_fifos_size, pairs_to_allocate;
	int rx_freelist_index, tx_freelist_index;
	ssvm_shared_header_t *sh = s->ssvm.sh;
	svm_fifo_segment_header_t *fsh = s->h;
	u8 rx_fifo_space, tx_fifo_space;
	uword space_available;
	void *oldheap;
	svm_fifo_t *f;
	int i;

	/* Parameter check */
	if (rx_fifo_size == 0 \|\| tx_fifo_size == 0 \|\| *n_fifo_pairs == 0)
	return;

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

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

	rx_rounded_data_size = (1 << (max_log2 (rx_fifo_size)));
	rx_freelist_index = max_log2 (rx_fifo_size)
	- max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);
	tx_rounded_data_size = (1 << (max_log2 (tx_fifo_size)));
	tx_freelist_index = max_log2 (tx_fifo_size)
	- max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE);

	/* Calculate space requirements */
	pair_size = 2 * sizeof (*f) + rx_rounded_data_size + tx_rounded_data_size;
	#if USE_DLMALLOC == 0
	space_available = s->ssvm.ssvm_size - mheap_bytes (sh->heap);
	#else
	space_available = s->ssvm.ssvm_size - mspace_usable_size (sh->heap);
	#endif

	pairs_to_allocate = clib_min (space_available / pair_size, *n_fifo_pairs);
	rx_fifos_size = (sizeof (f) + rx_rounded_data_size) pairs_to_allocate;
	tx_fifos_size = (sizeof (f) + tx_rounded_data_size) pairs_to_allocate;

	vec_validate_init_empty (fsh->free_fifos,
	clib_max (rx_freelist_index, tx_freelist_index),
	0);

	oldheap = ssvm_push_heap (sh);
	/* Allocate rx fifo space. May fail. */
	rx_fifo_space = clib_mem_alloc_aligned_at_offset
	(rx_fifos_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_fifos_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",
	rx_fifo_size, *n_fifo_pairs);

	if (tx_fifo_space)
	clib_mem_free (tx_fifo_space);
	else
	clib_warning ("tx fifo preallocation failure: size %d nfifos %d",
	tx_fifo_size, *n_fifo_pairs);
	ssvm_pop_heap (oldheap);
	return;
	}

	/* Carve rx fifo space */
	f = (svm_fifo_t *) rx_fifo_space;
	for (i = 0; i < pairs_to_allocate; 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 < pairs_to_allocate; 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;
	}

	/* Account for the pairs allocated */
	*n_fifo_pairs -= pairs_to_allocate;
	ssvm_pop_heap (oldheap);
	}

	/**
	* Initialize svm fifo segment shared header
	*/
	int
	svm_fifo_segment_init (svm_fifo_segment_private_t * s)
	{
	svm_fifo_segment_header_t *fsh;
	ssvm_shared_header_t *sh;
	void *oldheap;

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

	fsh = clib_mem_alloc (sizeof (*fsh));
	clib_memset (fsh, 0, sizeof (*fsh));
	s->h = sh->opaque[0] = fsh;

	ssvm_pop_heap (oldheap);

	sh->ready = 1;
	return (0);
	}

	/**
	* Create an svm fifo segment and initialize as master
	*/
	int
	svm_fifo_segment_create (svm_fifo_segment_main_t * sm,
	svm_fifo_segment_create_args_t * a)
	{
	svm_fifo_segment_private_t *s;
	int rv;

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

	if ((rv = ssvm_master_init (&s->ssvm, a->segment_type)))
	{
	pool_put (sm->segments, s);
	return (rv);
	}

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

	svm_fifo_segment_init (s);
	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_main_t * sm,
	svm_fifo_segment_create_args_t * a)
	{
	svm_fifo_segment_private_t *s;
	ssvm_shared_header_t *sh;
	u32 rnd_size = 0;
	u8 *heap;
	u32 pagesize = clib_mem_get_page_size ();

	pool_get (sm->segments, s);
	clib_memset (s, 0, sizeof (*s));

	rnd_size = (a->segment_size + (pagesize - 1)) & ~pagesize;

	#if USE_DLMALLOC == 0
	heap = mheap_alloc (0, rnd_size);
	if (heap == 0)
	{
	clib_unix_warning ("mheap alloc");
	pool_put (sm->segments, s);
	return -1;
	}
	{
	mheap_t *heap_header;
	heap_header = mheap_header (heap);
	heap_header->flags \|= MHEAP_FLAG_THREAD_SAFE;
	}
	#else
	heap = create_mspace (rnd_size, 1 /* locked */ );
	#endif

	s->ssvm.ssvm_size = rnd_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 = ~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;

	clib_memset (sh, 0, sizeof (*sh));
	sh->heap = heap;

	svm_fifo_segment_init (s);
	vec_add1 (a->new_segment_indices, s - sm->segments);

	return (0);
	}

	/**
	* Attach as slave to an svm fifo segment
	*/
	int
	svm_fifo_segment_attach (svm_fifo_segment_main_t * sm,
	svm_fifo_segment_create_args_t * a)
	{
	svm_fifo_segment_private_t *s;
	int rv;

	/* Allocate a fresh segment */
	pool_get (sm->segments, s);
	clib_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;
	if (a->segment_type == SSVM_SEGMENT_MEMFD)
	s->ssvm.fd = a->memfd_fd;
	else
	s->ssvm.attach_timeout = sm->timeout_in_seconds;

	if ((rv = ssvm_slave_init (&s->ssvm, a->segment_type)))
	{
	_vec_len (s) = vec_len (s) - 1;
	return (rv);
	}

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

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

	void
	svm_fifo_segment_delete (svm_fifo_segment_main_t * sm,
	svm_fifo_segment_private_t * s)
	{
	ssvm_delete (&s->ssvm);
	clib_memset (s, 0xfe, sizeof (*s));
	pool_put (sm->segments, s);
	}

	/**
	* Allocate fifo in svm segment
	*/
	svm_fifo_t *
	svm_fifo_segment_alloc_fifo (svm_fifo_segment_private_t * fs,
	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 = 0;
	void *oldheap;
	int freelist_index;

	/*
	* 4K minimum. It's not likely that anything good will happen
	* with a smaller 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 = fs->ssvm.sh;
	ssvm_lock_non_recursive (sh, 1);
	fsh = (svm_fifo_segment_header_t *) sh->opaque[0];

	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))
	{
	/* Preallocated and no fifo left. Don't even try */
	if (fsh->flags & FIFO_SEGMENT_F_IS_PREALLOCATED)
	goto done;

	oldheap = ssvm_push_heap (sh);
	allocate_new_fifo_chunk (fsh, data_size_in_bytes,
	FIFO_SEGMENT_ALLOC_CHUNK_SIZE);
	ssvm_pop_heap (oldheap);
	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 */
	clib_memset (f, 0, sizeof (*f));
	f->nitems = data_size_in_bytes;
	f->ooos_list_head = OOO_SEGMENT_INVALID_INDEX;
	f->ct_session_index = SVM_FIFO_INVALID_SESSION_INDEX;
	f->refcnt = 1;
	f->freelist_index = freelist_index;
	goto found;
	}
	break;
	case FIFO_SEGMENT_FREELIST_NONE:
	break;

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

	/* Catch all that allocates just one fifo. Note: this can fail,
	* in which case: create another segment */
	oldheap = ssvm_push_heap (sh);
	f = svm_fifo_create (data_size_in_bytes);
	ssvm_pop_heap (oldheap);
	if (PREDICT_FALSE (f == 0))
	goto done;
	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;
	}
	fsh->n_active_fifos++;

	done:
	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 < 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;
	}

	fsh->n_active_fifos--;
	ssvm_pop_heap (oldheap);
	ssvm_unlock_non_recursive (sh);
	}

	void
	svm_fifo_segment_main_init (svm_fifo_segment_main_t * sm, u64 baseva,
	u32 timeout_in_seconds)
	{
	sm->next_baseva = baseva;
	sm->timeout_in_seconds = timeout_in_seconds;
	}

	u32
	svm_fifo_segment_index (svm_fifo_segment_main_t * sm,
	svm_fifo_segment_private_t * s)
	{
	return s - sm->segments;
	}

	/**
	* Retrieve svm segments pool. Used only for debug purposes.
	*/
	svm_fifo_segment_private_t *
	svm_fifo_segment_segments_pool (svm_fifo_segment_main_t * sm)
	{
	return sm->segments;
	}

	/**
	* Get number of active fifos
	*/
	u32
	svm_fifo_segment_num_fifos (svm_fifo_segment_private_t * fifo_segment)
	{
	return fifo_segment->h->n_active_fifos;
	}

	u32
	svm_fifo_segment_num_free_fifos (svm_fifo_segment_private_t * fifo_segment,
	u32 fifo_size_in_bytes)
	{
	ssvm_shared_header_t *sh;
	svm_fifo_segment_header_t *fsh;
	svm_fifo_t *f;
	int i;
	u32 count = 0, rounded_data_size, freelist_index;

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

	/* Count all free fifos? */
	if (fifo_size_in_bytes == ~0)
	{
	for (i = 0; i < vec_len (fsh->free_fifos); i++)
	{
	f = fsh->free_fifos[i];
	if (f == 0)
	continue;

	while (f)
	{
	f = f->next;
	count++;
	}
	}
	return count;
	}

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

	if (freelist_index >= vec_len (fsh->free_fifos))
	return 0;

	f = fsh->free_fifos[freelist_index];
	if (f == 0)
	return 0;

	while (f)
	{
	f = f->next;
	count++;
	}
	return count;
	}

	void
	svm_fifo_segment_info (svm_fifo_segment_private_t * seg, char **address,
	size_t * size)
	{
	if (ssvm_type (&seg->ssvm) == SSVM_SEGMENT_PRIVATE)
	{
	#if USE_DLMALLOC == 0
	mheap_t *heap_header;

	*address = pointer_to_uword (seg->ssvm.sh->heap);
	heap_header = mheap_header (seg->ssvm.sh->heap);
	*size = heap_header->max_size;
	#else
	mspace_get_address_and_size (seg->ssvm.sh->heap, address, size);
	#endif
	}
	else
	{
	address = (char ) seg->ssvm.sh->ssvm_va;
	*size = seg->ssvm.ssvm_size;
	}
	}

	void *
	svm_fifo_segment_heap (svm_fifo_segment_private_t * seg)
	{
	return seg->ssvm.sh->heap;
	}

	u8 *
	format_svm_fifo_segment_type (u8 * s, va_list * args)
	{
	svm_fifo_segment_private_t *sp;
	sp = va_arg (args, svm_fifo_segment_private_t );
	ssvm_segment_type_t st = ssvm_type (&sp->ssvm);

	if (st == SSVM_SEGMENT_PRIVATE)
	s = format (s, "%s", "private-heap");
	else if (st == SSVM_SEGMENT_MEMFD)
	s = format (s, "%s", "memfd");
	else if (st == SSVM_SEGMENT_SHM)
	s = format (s, "%s", "shm");
	else
	s = format (s, "%s", "unknown");
	return s;
	}

	/**
	* Segment format function
	*/
	u8 *
	format_svm_fifo_segment (u8 * s, va_list * args)
	{
	svm_fifo_segment_private_t *sp
	= va_arg (args, svm_fifo_segment_private_t );
	int verbose __attribute__ ((unused)) = va_arg (*args, int);
	svm_fifo_segment_header_t *fsh = sp->h;
	u32 count, indent;
	svm_fifo_t *f;
	int i;

	indent = format_get_indent (s) + 2;
	#if USE_DLMALLOC == 0
	s = format (s, "%U segment heap: %U\n", format_white_space, indent,
	format_mheap, svm_fifo_segment_heap (sp), verbose);
	s = format (s, "%U segment has %u active fifos\n",
	format_white_space, indent, svm_fifo_segment_num_fifos (sp));
	#endif

	for (i = 0; i < vec_len (fsh->free_fifos); i++)
	{
	f = fsh->free_fifos[i];
	if (f == 0)
	continue;
	count = 0;
	while (f)
	{
	f = f->next;
	count++;
	}

	s = format (s, "%U%-5u Kb: %u free",
	format_white_space, indent + 2,
	1 << (i + max_log2 (FIFO_SEGMENT_MIN_FIFO_SIZE) - 10),
	count);
	}
	return s;
	}

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