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authorSteven Luong <sluong@cisco.com>2022-08-29 10:00:31 -0700
committerDamjan Marion <dmarion@0xa5.net>2022-08-30 18:12:03 +0000
commitfcb2132d74627178a5a83fabd0addf741654fe63 (patch)
tree3827e8414ebcbd54b74d3a3650b258da7bcf150d
parent76b8aa00f73390aba91d075125c51b4af6c48ebb (diff)
memif: Process bad descriptors correctly in memif_process_desc
When there is a bad descriptor, it may in the beginning, in the middle, or at the end of the batch if the batch has more than 3 descriptors. When processing a bad descriptor is encountered in the batch, we need to rollback n_buffers in memif_process_desc(), or the statement in the same function memif_add_copy_op (ptd, mb0 + src_off, bytes_to_copy, dst_off, n_buffers - 1); is wrong because it picks up the wrong buffer_vec_index of the bad descriptor while parsing a good descriptor immediately following the bad descriptor. n_buffers was incremented in the beginning of while (n_left) loop. The other problem is we should count the number of bad packets and reduce ptd->n_packets to get the correct number of packets for subsequent processing in device_input. The last fix is to check if n_buffers == 0 in device_input and skip doing any descriptor copy. This case can happen when all the descriptors are bad in the batch. Type: fix Signed-off-by: Steven Luong <sluong@cisco.com> Change-Id: I28ed1d87236b045657006755747b5750a9a733be
-rw-r--r--src/plugins/memif/node.c45
1 files changed, 35 insertions, 10 deletions
diff --git a/src/plugins/memif/node.c b/src/plugins/memif/node.c
index 5abd20abc35..2d7b71fa20a 100644
--- a/src/plugins/memif/node.c
+++ b/src/plugins/memif/node.c
@@ -248,6 +248,7 @@ memif_process_desc (vlib_main_t *vm, vlib_node_runtime_t *node,
u32 n_left = ptd->n_packets;
u32 packet_len;
int i = -1;
+ int bad_packets = 0;
/* construct copy and packet vector out of ring slots */
while (n_left)
@@ -268,7 +269,14 @@ memif_process_desc (vlib_main_t *vm, vlib_node_runtime_t *node,
mb0 = desc_data[i];
if (PREDICT_FALSE (desc_status[i].err))
- vlib_error_count (vm, node->node_index, MEMIF_INPUT_ERROR_BAD_DESC, 1);
+ {
+ vlib_error_count (vm, node->node_index, MEMIF_INPUT_ERROR_BAD_DESC,
+ 1);
+ bad_packets++;
+ ASSERT (n_buffers > 0);
+ n_buffers--;
+ goto next_packet;
+ }
else
do
{
@@ -298,9 +306,12 @@ memif_process_desc (vlib_main_t *vm, vlib_node_runtime_t *node,
po->packet_len = packet_len;
po++;
+ next_packet:
/* next packet */
n_left--;
}
+ ASSERT (ptd->n_packets >= bad_packets);
+ ptd->n_packets -= bad_packets;
return n_buffers;
}
static_always_inline void
@@ -462,6 +473,21 @@ memif_fill_buffer_mdata (vlib_main_t *vm, vlib_node_runtime_t *node,
}
}
+static_always_inline void
+memif_advance_ring (memif_ring_type_t type, memif_queue_t *mq,
+ memif_ring_t *ring, u16 cur_slot)
+{
+ if (type == MEMIF_RING_S2M)
+ {
+ __atomic_store_n (&ring->tail, cur_slot, __ATOMIC_RELEASE);
+ mq->last_head = cur_slot;
+ }
+ else
+ {
+ mq->last_tail = cur_slot;
+ }
+}
+
static_always_inline uword
memif_device_input_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
memif_if_t *mif, memif_ring_type_t type, u16 qid,
@@ -533,6 +559,13 @@ memif_device_input_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
else
n_buffers = memif_process_desc (vm, node, ptd, mif);
+ if (PREDICT_FALSE (n_buffers == 0))
+ {
+ /* All descriptors are bad. Release slots in the ring and bail */
+ memif_advance_ring (type, mq, ring, cur_slot);
+ goto refill;
+ }
+
/* allocate free buffers */
vec_validate_aligned (ptd->buffers, n_buffers - 1, CLIB_CACHE_LINE_BYTES);
n_alloc = vlib_buffer_alloc_from_pool (vm, ptd->buffers, n_buffers,
@@ -588,15 +621,7 @@ memif_device_input_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
}
/* release slots from the ring */
- if (type == MEMIF_RING_S2M)
- {
- __atomic_store_n (&ring->tail, cur_slot, __ATOMIC_RELEASE);
- mq->last_head = cur_slot;
- }
- else
- {
- mq->last_tail = cur_slot;
- }
+ memif_advance_ring (type, mq, ring, cur_slot);
/* prepare buffer template and next indices */
vnet_buffer (&ptd->buffer_template)->sw_if_index[VLIB_RX] = mif->sw_if_index;