buffers: configurable buffer fault injector

When configured at compile time via the cmake
VPP_BUFFER_FAULT_INJECTOR option, the buffer allocator will appear to
fail a certain fraction of the time.

By default, the allocator succeeds 80% of the time. Detailed command
line configuration options are available, but only when the image has
been compiled with cmake option described above:

    vlib { buffer-alloc-success-rate [0.0 ... 1.0]
           buffer-alloc-success-seed <nnnn> }

Modify vlib_buffer_pool_create(...) so 0 is always an invalid buffer
index.

Debug images: add checks for bad buffer index enqueues, and also
verify that f->n_vectors doesn't accidentally map one or more
instances of the frame poison pattern 0xfefefefe.

Type: improvement

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: Iab939858014463d1e664682805013d334d6fcbe5

1 files changed, 51 insertions, 0 deletions

diff --git a/src/vlib/main.c b/src/vlib/main.c
index f723d106120..fb3eb108736 100644
--- a/src/vlib/main.c
+++ b/src/vlib/main.c
@@ -190,6 +190,31 @@ vlib_get_frame_to_node (vlib_main_t * vm, u32 to_node_index)
   return vlib_get_frame (vm, f);
 }
 
+static inline void
+vlib_validate_frame_indices (vlib_frame_t * f)
+{
+  if (CLIB_DEBUG > 0)
+    {
+      int i;
+      u32 *from = vlib_frame_vector_args (f);
+
+      /* Check for bad buffer index values */
+      for (i = 0; i < f->n_vectors; i++)
+	{
+	  if (from[i] == 0)
+	    {
+	      clib_warning ("BUG: buffer index 0 at index %d", i);
+	      ASSERT (0);
+	    }
+	  else if (from[i] == 0xfefefefe)
+	    {
+	      clib_warning ("BUG: frame poison pattern at index %d", i);
+	      ASSERT (0);
+	    }
+	}
+    }
+}
+
 void
 vlib_put_frame_to_node (vlib_main_t * vm, u32 to_node_index, vlib_frame_t * f)
 {
@@ -199,6 +224,8 @@ vlib_put_frame_to_node (vlib_main_t * vm, u32 to_node_index, vlib_frame_t * f)
   if (f->n_vectors == 0)
     return;
 
+  vlib_validate_frame_indices (f);
+
   to_node = vlib_get_node (vm, to_node_index);
 
   vec_add2 (vm->node_main.pending_frames, p, 1);
@@ -432,6 +459,9 @@ vlib_put_next_frame_validate (vlib_main_t * vm,
   f = vlib_get_frame (vm, nf->frame);
 
   ASSERT (n_vectors_left <= VLIB_FRAME_SIZE);
+
+  vlib_validate_frame_indices (f);
+
   n_after = VLIB_FRAME_SIZE - n_vectors_left;
   n_before = f->n_vectors;
 
@@ -1986,6 +2016,20 @@ vlib_main_configure (vlib_main_t * vm, unformat_input_t * input)
 	;
       else if (unformat (input, "elog-post-mortem-dump"))
 	vm->elog_post_mortem_dump = 1;
+      else if (unformat (input, "buffer-alloc-success-rate %f",
+			 &vm->buffer_alloc_success_rate))
+	{
+	  if (VLIB_BUFFER_ALLOC_FAULT_INJECTOR == 0)
+	    return clib_error_return
+	      (0, "Buffer fault injection not configured");
+	}
+      else if (unformat (input, "buffer-alloc-success-seed %u",
+			 &vm->buffer_alloc_success_seed))
+	{
+	  if (VLIB_BUFFER_ALLOC_FAULT_INJECTOR == 0)
+	    return clib_error_return
+	      (0, "Buffer fault injection not configured");
+	}
       else
 	return unformat_parse_error (input);
     }
@@ -2147,6 +2191,13 @@ vlib_main (vlib_main_t * volatile vm, unformat_input_t * input)
   vec_validate (vm->processing_rpc_requests, 0);
   _vec_len (vm->processing_rpc_requests) = 0;
 
+  /* Default params for the buffer allocator fault injector, if configured */
+  if (VLIB_BUFFER_ALLOC_FAULT_INJECTOR > 0)
+    {
+      vm->buffer_alloc_success_seed = 0xdeaddabe;
+      vm->buffer_alloc_success_rate = 0.80;
+    }
+
   if ((error = vlib_call_all_config_functions (vm, input, 0 /* is_early */ )))
     goto done;