[dpdk-dev] [PATCH] The VMXNET3 PMD can't receive packet suddenly after a lot of traffic coming in

[Yong Wang]

On 7/23/15, 5:53 PM, "dev on behalf of Marco Lee" <dev-bounces at dpdk.org on behalf of mac_leehk at yahoo.com.hk> wrote:


>The RX of VMXNET3 PMD will have deadlock when a lot of traffic coming in.
>The root cause is due to mbuf allocation fail in vmxnet3_post_rx_bufs()
>and there is no error handling when it is called from vmxnet3_recv_pkts().
>The RXD will not have "free" mbuf for it but the counter still increment.

Can you describe what counter this refers to?

>Finally, no packet can be received.
>
>This fix is allocate the mbuf first, if the allocation is failed,
>then reuse the old mbuf. If the allocation is success,
>the vmxnet3_post_rx_bufs() will call vmxnet3_renew_desc()
>and RXD will be renew inside.

I didn’t see this part of logic implemented.

>
>Signed-off-by: Marco Lee <mac_leehk at yahoo.com.hk/marco.lee at ruckuswireless.com>
>---
> drivers/net/vmxnet3/vmxnet3_rxtx.c |   37 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 36 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/net/vmxnet3/vmxnet3_rxtx.c b/drivers/net/vmxnet3/vmxnet3_rxtx.c
>index 39ad6ef..cbed438 100644
>--- a/drivers/net/vmxnet3/vmxnet3_rxtx.c
>+++ b/drivers/net/vmxnet3/vmxnet3_rxtx.c
>@@ -421,6 +421,35 @@ vmxnet3_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
> 	return nb_tx;
> }
> 
>+static inline void
>+vmxnet3_renew_desc(vmxnet3_rx_queue_t *rxq, uint8_t ring_id,
>+		struct rte_mbuf *mbuf)
>+{
>+	uint32_t  val = 0;
>+	struct vmxnet3_cmd_ring *ring = &rxq->cmd_ring[ring_id];
>+

Remove this blank line.

>+	struct Vmxnet3_RxDesc *rxd;
>+	vmxnet3_buf_info_t *buf_info = &ring->buf_info[ring->next2fill];
>+
>+	rxd = (struct Vmxnet3_RxDesc *)(ring->base + ring->next2fill);
>+

nit: this can be merged with the above definition.

>+	if (ring->rid == 0)
>+		val = VMXNET3_RXD_BTYPE_HEAD;
>+	else
>+		val = VMXNET3_RXD_BTYPE_BODY;
>+	

Remove the trailing space here.
 
>+
>+	buf_info->m = mbuf;
>+	buf_info->len = (uint16_t)(mbuf->buf_len - RTE_PKTMBUF_HEADROOM);
>+	buf_info->bufPA = RTE_MBUF_DATA_DMA_ADDR_DEFAULT(mbuf);
>+
>+	rxd->addr = buf_info->bufPA;
>+	rxd->btype = val;
>+	rxd->len = buf_info->len;
>+	rxd->gen = ring->gen;
>+
>+	vmxnet3_cmd_ring_adv_next2fill(ring);
>+}
> /*
>  *  Allocates mbufs and clusters. Post rx descriptors with buffer details
>  *  so that device can receive packets in those buffers.
>@@ -578,6 +607,8 @@ vmxnet3_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
> 		if (nb_rx >= nb_pkts)
> 			break;
> 
>+		struct rte_mbuf *rep;

What does rep mean? Can you rename it to something easier to understand
(say newm, or m2)?

Also, please move the definition to the top of this block.

>+		rep = rte_rxmbuf_alloc(rxq->mb_pool);
> 		idx = rcd->rxdIdx;
> 		ring_idx = (uint8_t)((rcd->rqID == rxq->qid1) ? 0 : 1);
> 		rxd = (Vmxnet3_RxDesc *)rxq->cmd_ring[ring_idx].base + idx;
>@@ -651,13 +682,17 @@ vmxnet3_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
> 
> 		vmxnet3_rx_offload(rcd, rxm);
> 
>+		if (unlikely(rep == NULL)) {
>+			rep = rxm;
>+			goto rcd_done;
>+		}

Should this be moved earlier? Also need to update the rx_buf_alloc_failure
counter.

> 		rx_pkts[nb_rx++] = rxm;
> rcd_done:
> 		rxq->cmd_ring[ring_idx].next2comp = idx;
> 		VMXNET3_INC_RING_IDX_ONLY(rxq->cmd_ring[ring_idx].next2comp, rxq->cmd_ring[ring_idx].size);
> 
> 		/* It's time to allocate some new buf and renew descriptors */
>-		vmxnet3_post_rx_bufs(rxq, ring_idx);
>+		vmxnet3_renew_desc(rxq, ring_idx, rep);
> 		if (unlikely(rxq->shared->ctrl.updateRxProd)) {
> 			VMXNET3_WRITE_BAR0_REG(hw, rxprod_reg[ring_idx] + (rxq->queue_id * VMXNET3_REG_ALIGN),
> 					       rxq->cmd_ring[ring_idx].next2fill);
>-- 
>1.7.9.5
>