svm session: document unsupported fifo deq combinations

[vpp.git] / src / svm / svm_fifo.h

diff --git a/src/svm/svm_fifo.h b/src/svm/svm_fifo.h
index 0a3d17e..f7503c8 100644 (file)
--- a/src/svm/svm_fifo.h
+++ b/src/svm/svm_fifo.h
@@ -295,7 +295,7 @@ void svm_fifo_enqueue_nocopy (svm_fifo_t * f, u32 len);
  * Overwrite fifo head with new data
  *
  * This should be typically used by dgram transport protocols that need
- * to update the dgram header after dequeueing a chunk of data. It assumes
+ * to update the dgram header after dequeuing a chunk of data. It assumes
  * that the dgram header is at most spread over two chunks.
  *
  * @param f            fifo
@@ -307,7 +307,9 @@ void svm_fifo_overwrite_head (svm_fifo_t * f, u8 * src, u32 len);
  * Dequeue data from fifo
  *
  * Data is dequeued to consumer provided buffer and head is atomically
- * updated.
+ * updated. This should not be used in combination with ooo lookups. If
+ * ooo peeking of data is needed in combination with dequeuing use @ref
+ * svm_fifo_dequeue_drop.
  *
  * @param f            fifo
  * @param len          length of data to dequeue
@@ -669,6 +671,8 @@ svm_fifo_size (svm_fifo_t * f)
 static inline void
 svm_fifo_set_size (svm_fifo_t * f, u32 size)
 {
+  if (size > (1 << f->fs_hdr->max_log2_chunk_size))
+    return;
   fsh_virtual_mem_update (f->fs_hdr, f->slice_index, (int) f->size - size);
   f->size = size;
 }