X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fsvm%2Fsvm_fifo.c;h=3df67135cfd90e2e71e9550ef5be18d8d647c01a;hb=b020806806c0e6c54886cdb4347a5fd1f19504b0;hp=3824d9988667264700d7f1dfe1a7f24c19b29256;hpb=344ce4277885e448912fdfc35bcfaf130c74d086;p=vpp.git

diff --git a/src/svm/svm_fifo.c b/src/svm/svm_fifo.c
index 3824d998866..3df67135cfd 100644
--- a/src/svm/svm_fifo.c
+++ b/src/svm/svm_fifo.c
@@ -400,29 +400,66 @@ svm_fifo_init (svm_fifo_t * f, u32 size)
   f->ooos_list_head = OOO_SEGMENT_INVALID_INDEX;
   f->segment_index = SVM_FIFO_INVALID_INDEX;
   f->refcnt = 1;
-  f->default_chunk.start_byte = 0;
-  f->default_chunk.length = f->size;
-  f->default_chunk.next = f->start_chunk = f->end_chunk = &f->default_chunk;
+  f->head = f->tail = f->flags = 0;
   f->head_chunk = f->tail_chunk = f->ooo_enq = f->ooo_deq = f->start_chunk;
 }
 
+void
+svm_fifo_init_chunks (svm_fifo_t * f)
+{
+  svm_fifo_chunk_t *c, *prev;
+
+  if (f->start_chunk->next == f->start_chunk)
+    return;
+
+  f->flags |= SVM_FIFO_F_MULTI_CHUNK;
+  rb_tree_init (&f->ooo_enq_lookup);
+  rb_tree_init (&f->ooo_deq_lookup);
+
+  f->start_chunk->start_byte = 0;
+  prev = f->start_chunk;
+  c = prev->next;
+
+  while (c != f->start_chunk)
+    {
+      c->start_byte = prev->start_byte + prev->length;
+      prev = c;
+      c = c->next;
+    }
+}
+
 /**
  * Creates a fifo in the current heap. Fails vs blow up the process
  */
 svm_fifo_t *
 svm_fifo_create (u32 data_size_in_bytes)
 {
-  svm_fifo_t *f;
   u32 rounded_data_size;
+  svm_fifo_chunk_t *c;
+  svm_fifo_t *f;
 
-  /* always round fifo data size to the next highest power-of-two */
-  rounded_data_size = (1 << (max_log2 (data_size_in_bytes)));
-  f = clib_mem_alloc_aligned_or_null (sizeof (*f) + rounded_data_size,
-				      CLIB_CACHE_LINE_BYTES);
+  f = clib_mem_alloc_aligned_or_null (sizeof (*f), CLIB_CACHE_LINE_BYTES);
   if (f == 0)
     return 0;
 
   clib_memset (f, 0, sizeof (*f));
+
+  /* always round fifo data size to the next highest power-of-two */
+  rounded_data_size = (1 << (max_log2 (data_size_in_bytes)));
+  c = clib_mem_alloc_aligned_or_null (sizeof (*c) + rounded_data_size,
+				      CLIB_CACHE_LINE_BYTES);
+  if (!c)
+    {
+      clib_mem_free (f);
+      return 0;
+    }
+
+  c->next = c;
+  c->start_byte = 0;
+  c->length = data_size_in_bytes;
+  c->rb_index = RBTREE_TNIL_INDEX;
+  f->start_chunk = f->end_chunk = c;
+
   svm_fifo_init (f, data_size_in_bytes);
   return f;
 }
@@ -454,6 +491,60 @@ svm_fifo_chunk_includes_pos (svm_fifo_chunk_t * c, u32 pos)
   return (pos >= c->start_byte && pos < c->start_byte + c->length);
 }
 
+static rb_node_t *
+svm_fifo_find_node_rbtree (rb_tree_t * rt, u32 pos)
+{
+  rb_node_t *cur, *prev;
+
+  cur = rb_node (rt, rt->root);
+  if (PREDICT_FALSE (rb_node_is_tnil (rt, cur)))
+    return 0;
+
+  while (pos != cur->key)
+    {
+      prev = cur;
+      if (pos < cur->key)
+	{
+	  cur = rb_node_left (rt, cur);
+	  if (rb_node_is_tnil (rt, cur))
+	    {
+	      cur = rb_tree_predecessor (rt, prev);
+	      break;
+	    }
+	}
+      else
+	{
+	  cur = rb_node_right (rt, cur);
+	  if (rb_node_is_tnil (rt, cur))
+	    {
+	      cur = prev;
+	      break;
+	    }
+	}
+    }
+
+  if (rb_node_is_tnil (rt, cur))
+    return 0;
+
+  return cur;
+}
+
+static svm_fifo_chunk_t *
+svm_fifo_find_chunk_rbtree (rb_tree_t * rt, u32 pos)
+{
+  svm_fifo_chunk_t *c;
+  rb_node_t *n;
+
+  n = svm_fifo_find_node_rbtree (rt, pos);
+  if (!n)
+    return 0;
+  c = uword_to_pointer (n->opaque, svm_fifo_chunk_t *);
+  if (svm_fifo_chunk_includes_pos (c, pos))
+    return c;
+
+  return 0;
+}
+
 /**
  * Find chunk for given byte position
  *
@@ -465,42 +556,170 @@ svm_fifo_chunk_includes_pos (svm_fifo_chunk_t * c, u32 pos)
 static svm_fifo_chunk_t *
 svm_fifo_find_chunk (svm_fifo_t * f, u32 pos)
 {
-  rb_tree_t *rt = &f->chunk_lookup;
-  rb_node_t *cur, *prev;
   svm_fifo_chunk_t *c;
 
-  cur = rb_node (rt, rt->root);
-  while (pos != cur->key)
+  c = f->start_chunk;
+  do
     {
-      prev = cur;
-      if (pos < cur->key)
-	cur = rb_node_left (rt, cur);
-      else
-	cur = rb_node_right (rt, cur);
+      if (svm_fifo_chunk_includes_pos (c, pos))
+	return c;
+      c = c->next;
+    }
+  while (c != f->start_chunk);
+
+  return 0;
+}
+
+static void
+svm_fifo_update_ooo_enq (svm_fifo_t * f, u32 ref_pos, u32 start_pos,
+			 u32 end_pos)
+{
+  rb_tree_t *rt = &f->ooo_enq_lookup;
+  svm_fifo_chunk_t *c;
+  rb_node_t *cur;
 
-      if (rb_node_is_tnil (rt, cur))
+  if (svm_fifo_chunk_includes_pos (f->ooo_enq, start_pos)
+      && svm_fifo_chunk_includes_pos (f->ooo_enq, end_pos)
+      && ref_pos < start_pos)
+    return;
+
+  if (rt->root == RBTREE_TNIL_INDEX)
+    {
+      c = f->tail_chunk;
+      c->rb_index = rb_tree_add2 (rt, c->start_byte, pointer_to_uword (c));
+    }
+  else
+    {
+      cur = svm_fifo_find_node_rbtree (rt, start_pos);
+      c = uword_to_pointer (cur->opaque, svm_fifo_chunk_t *);
+      if (ref_pos > start_pos && c->start_byte > start_pos)
 	{
-	  /* Hit tnil as a left child. Find predecessor */
-	  if (pos < prev->key)
-	    {
-	      cur = rb_tree_predecessor (rt, prev);
-	      c = uword_to_pointer (cur->opaque, svm_fifo_chunk_t *);
-	      if (svm_fifo_chunk_includes_pos (c, pos))
-		return c;
-	      return 0;
-	    }
-	  /* Hit tnil as a right child. Check if this is the one */
-	  c = uword_to_pointer (prev->opaque, svm_fifo_chunk_t *);
-	  if (svm_fifo_chunk_includes_pos (c, pos))
-	    return c;
+	  c = f->end_chunk;
+	  ASSERT (c->rb_index != RBTREE_TNIL_INDEX);
+	}
+    }
 
-	  return 0;
+  if (svm_fifo_chunk_includes_pos (c, start_pos))
+    f->ooo_enq = c;
+
+  if (svm_fifo_chunk_includes_pos (c, end_pos) && ref_pos < end_pos)
+    return;
+
+  do
+    {
+      c = c->next;
+      if (c->rb_index != RBTREE_TNIL_INDEX)
+	break;
+
+      c->rb_index = rb_tree_add2 (rt, c->start_byte, pointer_to_uword (c));
+
+      if (svm_fifo_chunk_includes_pos (c, start_pos))
+	f->ooo_enq = c;
+
+    }
+  while (!svm_fifo_chunk_includes_pos (c, end_pos));
+}
+
+static void
+svm_fifo_update_ooo_deq (svm_fifo_t * f, u32 ref_pos, u32 start_pos,
+			 u32 end_pos)
+{
+  rb_tree_t *rt = &f->ooo_deq_lookup;
+  rb_node_t *cur;
+  svm_fifo_chunk_t *c;
+
+  if (svm_fifo_chunk_includes_pos (f->ooo_deq, start_pos)
+      && svm_fifo_chunk_includes_pos (f->ooo_deq, end_pos)
+      && ref_pos < start_pos)
+    return;
+
+  if (rt->root == RBTREE_TNIL_INDEX)
+    {
+      c = f->head_chunk;
+      c->rb_index = rb_tree_add2 (rt, c->start_byte, pointer_to_uword (c));
+    }
+  else
+    {
+      cur = svm_fifo_find_node_rbtree (rt, start_pos);
+      c = uword_to_pointer (cur->opaque, svm_fifo_chunk_t *);
+      if (ref_pos > start_pos && c->start_byte > start_pos)
+	{
+	  c = f->end_chunk;
+	  ASSERT (c->rb_index != RBTREE_TNIL_INDEX);
 	}
     }
 
-  if (!rb_node_is_tnil (rt, cur))
-    return uword_to_pointer (cur->opaque, svm_fifo_chunk_t *);
-  return 0;
+  if (svm_fifo_chunk_includes_pos (c, start_pos))
+    f->ooo_deq = c;
+
+  if (svm_fifo_chunk_includes_pos (c, end_pos) && ref_pos < end_pos)
+    return;
+
+  do
+    {
+      c = c->next;
+      if (c->rb_index != RBTREE_TNIL_INDEX)
+	break;
+
+      c->rb_index = rb_tree_add2 (rt, c->start_byte, pointer_to_uword (c));
+
+      if (svm_fifo_chunk_includes_pos (c, start_pos))
+	f->ooo_deq = c;
+
+    }
+  while (!svm_fifo_chunk_includes_pos (c, end_pos));
+}
+
+void
+svm_fifo_ooo_deq_track (svm_fifo_t * f, u32 start_pos, u32 end_pos)
+{
+  rb_tree_t *rt = &f->ooo_deq_lookup;
+  svm_fifo_chunk_t *c;
+
+  if (svm_fifo_chunk_includes_pos (f->ooo_deq, end_pos)
+      && start_pos < end_pos)
+    return;
+
+  c = f->ooo_deq->next;
+  do
+    {
+      ASSERT (c->rb_index == RBTREE_TNIL_INDEX);
+      rb_tree_add2 (rt, c->start_byte, pointer_to_uword (c));
+
+      c = c->next;
+    }
+  while (!svm_fifo_chunk_includes_pos (c, end_pos));
+}
+
+static svm_fifo_chunk_t *
+svm_fifo_lookup_clear_chunks (svm_fifo_t * f, rb_tree_t * rt,
+			      svm_fifo_chunk_t * start, u32 start_pos,
+			      u32 end_pos)
+{
+  svm_fifo_chunk_t *c;
+  rb_node_t *n;
+
+  /* Nothing to do if still in the same chunk and not wrapped */
+  if (svm_fifo_chunk_includes_pos (start, end_pos) && start_pos < end_pos)
+    return start;
+
+  c = start;
+  do
+    {
+      if (c->rb_index == RBTREE_TNIL_INDEX)
+	{
+	  c = c->next;
+	  continue;
+	}
+
+      n = rb_node (rt, c->rb_index);
+      rb_tree_del_node (rt, n);
+      c->rb_index = RBTREE_TNIL_INDEX;
+      c = c->next;
+    }
+  while (!svm_fifo_chunk_includes_pos (c, end_pos));
+
+  return c;
 }
 
 static inline void
@@ -545,11 +764,102 @@ svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c)
    * that this is called with the heap where the rbtree's pool is pushed. */
   if (!(f->flags & SVM_FIFO_F_MULTI_CHUNK))
     {
-      rb_tree_init (&f->chunk_lookup);
-      rb_tree_add2 (&f->chunk_lookup, 0, pointer_to_uword (f->start_chunk));
+      ASSERT (f->start_chunk->next == f->start_chunk);
+      rb_tree_init (&f->ooo_enq_lookup);
+      rb_tree_init (&f->ooo_deq_lookup);
       f->flags |= SVM_FIFO_F_MULTI_CHUNK;
     }
 
+  /* If fifo is not wrapped, update the size now */
+  if (!svm_fifo_is_wrapped (f))
+    {
+      /* Initialize chunks and add to lookup rbtree */
+      cur = c;
+      if (f->new_chunks)
+	{
+	  prev = f->new_chunks;
+	  while (prev->next)
+	    prev = prev->next;
+	  prev->next = c;
+	}
+      else
+	prev = f->end_chunk;
+
+      while (cur)
+	{
+	  cur->start_byte = prev->start_byte + prev->length;
+	  cur->rb_index = RBTREE_TNIL_INDEX;
+	  prev = cur;
+	  cur = cur->next;
+	}
+
+      ASSERT (!f->new_chunks);
+      svm_fifo_grow (f, c);
+      return;
+    }
+
+  /* Wrapped */
+  if (f->flags & SVM_FIFO_F_SINGLE_THREAD_OWNED)
+    {
+      ASSERT (f->master_thread_index == os_get_thread_index ());
+
+      if (!f->new_chunks && f->head_chunk != f->tail_chunk)
+	{
+	  u32 head = 0, tail = 0;
+	  f_load_head_tail_cons (f, &head, &tail);
+
+	  svm_fifo_chunk_t *tmp = f->tail_chunk->next;
+
+	  prev = f->tail_chunk;
+	  u32 add_bytes = 0;
+	  cur = prev->next;
+	  while (cur != f->start_chunk)
+	    {
+	      /* remove any existing rb_tree entry */
+	      if (cur->rb_index != RBTREE_TNIL_INDEX)
+		{
+		  rb_tree_del (&f->ooo_enq_lookup, cur->start_byte);
+		  rb_tree_del (&f->ooo_deq_lookup, cur->start_byte);
+		}
+	      cur->rb_index = RBTREE_TNIL_INDEX;
+	      cur = cur->next;
+	    }
+
+	  /* insert new chunk after the tail_chunk */
+	  f->tail_chunk->next = c;
+	  while (c)
+	    {
+	      add_bytes += c->length;
+	      c->start_byte = prev->start_byte + prev->length;
+	      cur->rb_index = RBTREE_TNIL_INDEX;
+
+	      prev = c;
+	      c = c->next;
+	    }
+	  prev->next = tmp;
+
+	  /* shift existing chunks along */
+	  cur = tmp;
+	  while (cur != f->start_chunk)
+	    {
+	      cur->start_byte = prev->start_byte + prev->length;
+	      prev = cur;
+	      cur = cur->next;
+	    }
+
+	  f->size += add_bytes;
+	  f->nitems = f->size - 1;
+	  f->new_chunks = 0;
+	  head += add_bytes;
+
+	  clib_atomic_store_rel_n (&f->head, head);
+	  ASSERT (svm_fifo_is_sane (f));
+
+	  return;
+	}
+    }
+
+  /* Wrapped, and optimization of single-thread-owned fifo cannot be applied */
   /* Initialize chunks and add to lookup rbtree */
   cur = c;
   if (f->new_chunks)
@@ -565,20 +875,11 @@ svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c)
   while (cur)
     {
       cur->start_byte = prev->start_byte + prev->length;
-      rb_tree_add2 (&f->chunk_lookup, cur->start_byte,
-		    pointer_to_uword (cur));
+      cur->rb_index = RBTREE_TNIL_INDEX;
       prev = cur;
       cur = cur->next;
     }
 
-  /* If fifo is not wrapped, update the size now */
-  if (!svm_fifo_is_wrapped (f))
-    {
-      ASSERT (!f->new_chunks);
-      svm_fifo_grow (f, c);
-      return;
-    }
-
   /* Postpone size update */
   if (!f->new_chunks)
     {
@@ -602,7 +903,11 @@ svm_fifo_collect_chunks (svm_fifo_t * f)
   cur = list;
   while (cur)
     {
-      rb_tree_del (&f->chunk_lookup, cur->start_byte);
+      if (cur->rb_index != RBTREE_TNIL_INDEX)
+	{
+	  rb_tree_del (&f->ooo_enq_lookup, cur->start_byte);
+	  rb_tree_del (&f->ooo_deq_lookup, cur->start_byte);
+	}
       cur = cur->next;
     }
 
@@ -612,7 +917,7 @@ svm_fifo_collect_chunks (svm_fifo_t * f)
 void
 svm_fifo_try_shrink (svm_fifo_t * f, u32 head, u32 tail)
 {
-  u32 len_to_shrink = 0, tail_pos, len;
+  u32 len_to_shrink = 0, tail_pos, len, last_pos;
   svm_fifo_chunk_t *cur, *prev, *next, *start;
 
   tail_pos = tail;
@@ -635,13 +940,24 @@ svm_fifo_try_shrink (svm_fifo_t * f, u32 head, u32 tail)
    * - not wrapped
    * - last used byte less than start of last chunk
    */
-  if (tail_pos >= head && tail_pos <= f->end_chunk->start_byte)
+  if (tail_pos >= head && tail_pos < f->end_chunk->start_byte)
     {
       /* Lookup the last position not to be removed. Since size still needs
-       * to be nitems + 1, nitems must fall within the usable space */
-      tail_pos = tail_pos > 0 ? tail_pos - 1 : tail_pos;
-      prev = svm_fifo_find_chunk (f, clib_max (f->nitems, tail_pos));
+       * to be nitems + 1, nitems must fall within the usable space. Also,
+       * first segment is not removable, so tail_pos can be 0. */
+      last_pos = tail_pos > 0 ? tail_pos - 1 : tail_pos;
+      prev = svm_fifo_find_chunk (f, clib_max (f->nitems, last_pos));
       next = prev->next;
+      /* If tail_pos is first position in next, skip the chunk, otherwise,
+       * we must update the tail and, if fifo size is 0, even the head.
+       * We should not invalidate the tail for the caller and must not change
+       * consumer owned variables from code that's typically called by the
+       * producer */
+      if (next->start_byte == tail_pos)
+	{
+	  prev = next;
+	  next = next->next;
+	}
       while (next != f->start_chunk)
 	{
 	  cur = next;
@@ -714,7 +1030,8 @@ svm_fifo_reduce_size (svm_fifo_t * f, u32 len, u8 try_shrink)
 void
 svm_fifo_free_chunk_lookup (svm_fifo_t * f)
 {
-  rb_tree_free_nodes (&f->chunk_lookup);
+  rb_tree_free_nodes (&f->ooo_enq_lookup);
+  rb_tree_free_nodes (&f->ooo_deq_lookup);
 }
 
 void
@@ -776,7 +1093,13 @@ svm_fifo_enqueue (svm_fifo_t * f, u32 len, const u8 * src)
 
   /* collect out-of-order segments */
   if (PREDICT_FALSE (f->ooos_list_head != OOO_SEGMENT_INVALID_INDEX))
-    len += ooo_segment_try_collect (f, len, &tail);
+    {
+      len += ooo_segment_try_collect (f, len, &tail);
+      if (f->flags & SVM_FIFO_F_MULTI_CHUNK)
+	f->tail_chunk = svm_fifo_lookup_clear_chunks (f, &f->ooo_enq_lookup,
+						      f->tail_chunk, f->tail,
+						      tail);
+    }
 
   /* store-rel: producer owned index (paired with load-acq in consumer) */
   clib_atomic_store_rel_n (&f->tail, tail);
@@ -813,8 +1136,9 @@ svm_fifo_enqueue_with_offset (svm_fifo_t * f, u32 offset, u32 len, u8 * src)
   ooo_segment_add (f, offset, head, tail, len);
   tail_idx = (tail + offset) % f->size;
 
-  if (!svm_fifo_chunk_includes_pos (f->ooo_enq, tail_idx))
-    f->ooo_enq = svm_fifo_find_chunk (f, tail_idx);
+  if (f->flags & SVM_FIFO_F_MULTI_CHUNK)
+    svm_fifo_update_ooo_enq (f, f->tail, tail_idx,
+			     (tail_idx + len) % f->size);
 
   svm_fifo_copy_to_chunk (f, f->ooo_enq, tail_idx, src, len, &f->ooo_enq);
 
@@ -833,6 +1157,12 @@ svm_fifo_enqueue_nocopy (svm_fifo_t * f, u32 len)
   /* load-relaxed: producer owned index */
   tail = f->tail;
   tail = (tail + len) % f->size;
+
+  if (f->flags & SVM_FIFO_F_MULTI_CHUNK)
+    f->tail_chunk = svm_fifo_lookup_clear_chunks (f, &f->ooo_enq_lookup,
+						  f->tail_chunk, f->tail,
+						  tail);
+
   /* store-rel: producer owned index (paired with load-acq in consumer) */
   clib_atomic_store_rel_n (&f->tail, tail);
 }
@@ -878,8 +1208,9 @@ svm_fifo_peek (svm_fifo_t * f, u32 offset, u32 len, u8 * dst)
 
   len = clib_min (cursize - offset, len);
   head_idx = (head + offset) % f->size;
-  if (!svm_fifo_chunk_includes_pos (f->ooo_deq, head_idx))
-    f->ooo_deq = svm_fifo_find_chunk (f, head_idx);
+
+  if (f->flags & SVM_FIFO_F_MULTI_CHUNK)
+    svm_fifo_update_ooo_deq (f, head, head_idx, (head_idx + len) % f->size);
 
   svm_fifo_copy_from_chunk (f, f->ooo_deq, head_idx, dst, len, &f->ooo_deq);
   return len;
@@ -897,14 +1228,22 @@ svm_fifo_dequeue_drop (svm_fifo_t * f, u32 len)
   if (PREDICT_FALSE (cursize == 0))
     return SVM_FIFO_EEMPTY;
 
-  svm_fifo_trace_add (f, tail, total_drop_bytes, 3);
-
   /* number of bytes we're going to drop */
   total_drop_bytes = clib_min (cursize, len);
 
+  svm_fifo_trace_add (f, tail, total_drop_bytes, 3);
+
   /* move head */
   head = (head + total_drop_bytes) % f->size;
 
+  if (f->flags & SVM_FIFO_F_MULTI_CHUNK)
+    f->head_chunk = svm_fifo_lookup_clear_chunks (f, &f->ooo_deq_lookup,
+						  f->head_chunk, f->head,
+						  head);
+
+  if (PREDICT_FALSE (f->flags & SVM_FIFO_F_GROW))
+    svm_fifo_try_grow (f, head);
+
   /* store-rel: consumer owned index (paired with load-acq in producer) */
   clib_atomic_store_rel_n (&f->head, head);
 
@@ -916,6 +1255,15 @@ svm_fifo_dequeue_drop_all (svm_fifo_t * f)
 {
   /* consumer foreign index */
   u32 tail = clib_atomic_load_acq_n (&f->tail);
+
+  if (f->flags & SVM_FIFO_F_MULTI_CHUNK)
+    f->head_chunk = svm_fifo_lookup_clear_chunks (f, &f->ooo_deq_lookup,
+						  f->head_chunk, tail,
+						  tail - 1);
+
+  if (PREDICT_FALSE (f->flags & SVM_FIFO_F_GROW))
+    svm_fifo_try_grow (f, tail);
+
   /* store-rel: consumer owned index (paired with load-acq in producer) */
   clib_atomic_store_rel_n (&f->head, tail);
 }
@@ -1041,6 +1389,93 @@ svm_fifo_del_subscriber (svm_fifo_t * f, u8 subscriber)
     }
 }
 
+u8
+svm_fifo_is_sane (svm_fifo_t * f)
+{
+  if (f->size - 1 != f->nitems && !(f->flags & SVM_FIFO_F_SHRINK))
+    return 0;
+  if (!svm_fifo_chunk_includes_pos (f->head_chunk, f->head))
+    return 0;
+  if (!svm_fifo_chunk_includes_pos (f->tail_chunk, f->tail))
+    return 0;
+
+  if (f->start_chunk->next != f->start_chunk)
+    {
+      svm_fifo_chunk_t *c, *prev = 0, *tmp;
+      u32 size = 0;
+
+      if (!(f->flags & SVM_FIFO_F_MULTI_CHUNK))
+	return 0;
+
+      c = f->start_chunk;
+      do
+	{
+	  tmp = svm_fifo_find_chunk (f, c->start_byte);
+	  if (tmp != c)
+	    return 0;
+	  if (prev && (prev->start_byte + prev->length != c->start_byte))
+	    return 0;
+
+	  if (c->rb_index != RBTREE_TNIL_INDEX)
+	    {
+	      u8 found = 0;
+
+	      tmp = svm_fifo_find_chunk_rbtree (&f->ooo_enq_lookup,
+						c->start_byte);
+	      if (tmp)
+		{
+		  found = 1;
+		  if (tmp != c)
+		    return 0;
+		}
+
+	      tmp = svm_fifo_find_chunk_rbtree (&f->ooo_deq_lookup,
+						c->start_byte);
+	      if (tmp)
+		{
+		  if (found)
+		    return 0;
+
+		  found = 1;
+		  if (tmp != c)
+		    return 0;
+		}
+	      if (!found)
+		return 0;
+	    }
+
+	  size += c->length;
+	  prev = c;
+	  c = c->next;
+	}
+      while (c != f->start_chunk);
+
+      if (size != f->size)
+	return 0;
+    }
+
+  return 1;
+}
+
+u8
+svm_fifo_set_single_thread_owned (svm_fifo_t * f)
+{
+  if (f->flags & SVM_FIFO_F_SINGLE_THREAD_OWNED)
+    {
+      if (f->master_thread_index == os_get_thread_index ())
+	{
+	  /* just a duplicate call */
+	  return 0;
+	}
+
+      /* already owned by another thread */
+      return 1;
+    }
+
+  f->flags |= SVM_FIFO_F_SINGLE_THREAD_OWNED;
+  return 0;
+}
+
 u8 *
 format_ooo_segment (u8 * s, va_list * args)
 {