avf: put sentinel at correct place

The previous fix was adding the sentinel before refilling rx,
which gave the NIC time to overwrite it with a new descriptor.

Ticket: VPP-2087
Type: fix
Fixes: 8b4d474abd62c623502ad9a4a279a9b4535ca0c1

Change-Id: I32bde4a763a62fb66c5c3871d9f10af6066e2d47
Signed-off-by: Vratko Polak <vrpolak@cisco.com>

2 files changed, 6 insertions, 6 deletions

diff --git a/src/plugins/avf/input.c b/src/plugins/avf/input.c
index 3c3d6c07c2d..ca69407fc59 100644
--- a/src/plugins/avf/input.c
+++ b/src/plugins/avf/input.c
@@ -125,6 +125,9 @@ avf_rxq_refill (vlib_main_t * vm, vlib_node_runtime_t * node, avf_rxq_t * rxq,
       n_alloc -= 8;
     }
 
+  /* RXQ can be smaller than 256 packets, especially if jumbo. */
+  rxq->descs[slot].qword[1] = 0;
+
   avf_tail_write (rxq->qrx_tail, slot);
 }
 
@@ -423,9 +426,6 @@ no_more_desc:
   rxq->next = next;
   rxq->n_enqueued -= n_rx_packets + n_tail_desc;
 
-  /* avoid eating our own tail */
-  rxq->descs[(next + rxq->n_enqueued) & mask].qword[1] = 0;
-
 #if defined(CLIB_HAVE_VEC256) || defined(CLIB_HAVE_VEC128)
   or_qw1 |= or_q1x4[0] | or_q1x4[1] | or_q1x4[2] | or_q1x4[3];
 #endif
diff --git a/src/plugins/dev_iavf/rx_node.c b/src/plugins/dev_iavf/rx_node.c
index 946adb1df1b..ee6d7e8def0 100644
--- a/src/plugins/dev_iavf/rx_node.c
+++ b/src/plugins/dev_iavf/rx_node.c
@@ -111,6 +111,9 @@ iavf_rxq_refill (vlib_main_t *vm, vlib_node_runtime_t *node,
       n_alloc -= 8;
     }
 
+  /* RXQ can be smaller than 256 packets, especially if jumbo. */
+  arq->descs[slot].qword[1] = 0;
+
   __atomic_store_n (arq->qrx_tail, slot, __ATOMIC_RELEASE);
 }
 
@@ -399,9 +402,6 @@ no_more_desc:
   arq->next = next;
   arq->n_enqueued -= n_rx_packets + n_tail_desc;
 
-  /* avoid eating our own tail */
-  arq->descs[(next + arq->n_enqueued) & mask].qword[1] = 0;
-
 #if defined(CLIB_HAVE_VEC256) || defined(CLIB_HAVE_VEC128)
   or_qw1 |= or_q1x4[0] | or_q1x4[1] | or_q1x4[2] | or_q1x4[3];
 #endif