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, 11 insertions, 0 deletions

diff --git a/src/vlib/buffer_funcs.h b/src/vlib/buffer_funcs.h
index 98ee2055833..b2076e60de4 100644
--- a/src/vlib/buffer_funcs.h
+++ b/src/vlib/buffer_funcs.h
@@ -571,6 +571,17 @@ vlib_buffer_alloc_from_pool (vlib_main_t * vm, u32 * buffers, u32 n_buffers,
   vlib_buffer_pool_thread_t *bpt;
   u32 *src, *dst, len, n_left;
 
+  /* If buffer allocation fault injection is configured */
+  if (VLIB_BUFFER_ALLOC_FAULT_INJECTOR > 0)
+    {
+      u32 vlib_buffer_alloc_may_fail (vlib_main_t *, u32);
+
+      /* See how many buffers we're willing to allocate */
+      n_buffers = vlib_buffer_alloc_may_fail (vm, n_buffers);
+      if (n_buffers == 0)
+	return (n_buffers);
+    }
+
   bp = vec_elt_at_index (bm->buffer_pools, buffer_pool_index);
   bpt = vec_elt_at_index (bp->threads, vm->thread_index);