Re: [dpdk-stable] [EXT] Re: [PATCH 1/2] net/qede: fix assignment of Rx/Tx handlers

[Rasesh Mody <rmody@marvell.com>]

Hi Ferruh,

>From: Ferruh Yigit <ferruh.yigit@intel.com>
>Sent: Tuesday, May 05, 2020 2:01 AM
>
>On 5/5/2020 4:09 AM, Rasesh Mody wrote:
>> Fix to assign dummy Rx/Tx handlers in dev_stop.
>> For MTU set, assignment of the appropriate Rx/Tx handlers will be
>> handled by dev_start/dev_stop.
>>
>> Fixes: 81f8804992c9 ("net/qede: enhance Rx CPU utilization")
>> Fixes: 8de0c4201926 ("net/qede: fix odd number of queues usage in 100G
>> mode")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Rasesh Mody <rmody@marvell.com>
>> Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
>> ---
>>  drivers/net/qede/qede_ethdev.c | 33 ++++++++++++++++-----------------
>>  1 file changed, 16 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/net/qede/qede_ethdev.c
>> b/drivers/net/qede/qede_ethdev.c index e71fa1e6a..726daa3e3 100644
>> --- a/drivers/net/qede/qede_ethdev.c
>> +++ b/drivers/net/qede/qede_ethdev.c
>> @@ -320,13 +320,19 @@ qede_interrupt_handler(void *param)  }
>>
>>  static void
>> -qede_assign_rxtx_handlers(struct rte_eth_dev *dev)
>> +qede_assign_rxtx_handlers(struct rte_eth_dev *dev, bool is_dummy)
>>  {
>>  	uint64_t tx_offloads = dev->data->dev_conf.txmode.offloads;
>>  	struct qede_dev *qdev = dev->data->dev_private;
>>  	struct ecore_dev *edev = &qdev->edev;
>>  	bool use_tx_offload = false;
>>
>> +	if (is_dummy) {
>> +		dev->rx_pkt_burst = qede_rxtx_pkts_dummy;
>> +		dev->tx_pkt_burst = qede_rxtx_pkts_dummy;
>> +		return;
>> +	}
>> +
>>  	if (ECORE_IS_CMT(edev)) {
>>  		dev->rx_pkt_burst = qede_recv_pkts_cmt;
>>  		dev->tx_pkt_burst = qede_xmit_pkts_cmt; @@ -1150,7
>+1156,9 @@
>> static int qede_dev_start(struct rte_eth_dev *eth_dev)
>>  	/* Start/resume traffic */
>>  	qede_fastpath_start(edev);
>>
>> -	qede_assign_rxtx_handlers(eth_dev);
>> +	/* Assign I/O handlers */
>> +	qede_assign_rxtx_handlers(eth_dev, false);
>> +
>>  	DP_INFO(edev, "Device started\n");
>>
>>  	return 0;
>> @@ -1166,6 +1174,11 @@ static void qede_dev_stop(struct rte_eth_dev
>> *eth_dev)
>>
>>  	PMD_INIT_FUNC_TRACE(edev);
>>
>> +	/* Replace I/O functions with dummy ones. It cannot
>> +	 * be set to NULL because rte_eth_rx_burst() doesn't check for NULL.
>> +	 */
>> +	qede_assign_rxtx_handlers(eth_dev, true);
>> +
>
>Why need to assign dummy handlers on stop(), what happens if you keep
>them as they are as many PMD does?

It helps in preventing crash when queues are still in use.

Thanks!
-Rasesh

>
>>  	/* Disable vport */
>>  	if (qede_activate_vport(eth_dev, false))
>>  		return;
>> @@ -2316,11 +2329,6 @@ static int qede_set_mtu(struct rte_eth_dev
>*dev, uint16_t mtu)
>>  			dev->data->min_rx_buf_size);
>>  		return -EINVAL;
>>  	}
>> -	/* Temporarily replace I/O functions with dummy ones. It cannot
>> -	 * be set to NULL because rte_eth_rx_burst() doesn't check for NULL.
>> -	 */
>> -	dev->rx_pkt_burst = qede_rxtx_pkts_dummy;
>> -	dev->tx_pkt_burst = qede_rxtx_pkts_dummy;
>>  	if (dev->data->dev_started) {
>>  		dev->data->dev_started = 0;
>>  		qede_dev_stop(dev);
>> @@ -2359,15 +2367,6 @@ static int qede_set_mtu(struct rte_eth_dev
>*dev, uint16_t mtu)
>>  	/* update max frame size */
>>  	dev->data->dev_conf.rxmode.max_rx_pkt_len = max_rx_pkt_len;
>>
>> -	/* Reassign back */
>> -	qede_assign_rxtx_handlers(dev);
>> -	if (ECORE_IS_CMT(edev)) {
>> -		dev->rx_pkt_burst = qede_recv_pkts_cmt;
>> -		dev->tx_pkt_burst = qede_xmit_pkts_cmt;
>> -	} else {
>> -		dev->rx_pkt_burst = qede_recv_pkts;
>> -		dev->tx_pkt_burst = qede_xmit_pkts;
>> -	}
>>  	return 0;
>>  }
>>
>> @@ -2570,7 +2569,7 @@ static int qede_common_dev_init(struct
>rte_eth_dev *eth_dev, bool is_vf)
>>  	strncpy((char *)params.name, QEDE_PMD_VER_PREFIX,
>>  		QEDE_PMD_DRV_VER_STR_SIZE);
>>
>> -	qede_assign_rxtx_handlers(eth_dev);
>> +	qede_assign_rxtx_handlers(eth_dev, true);
>>  	eth_dev->tx_pkt_prepare = qede_xmit_prep_pkts;
>>
>>  	/* For CMT mode device do periodic polling for slowpath events.
>>