Re: [dpdk-dev] [PATCH 1/2] net/pcap: multiple queues fix

[Ido Goshen <Ido@cgstowernetworks.com>]

See Inline prefixed with [ido]

-----Original Message-----
From: Ferruh Yigit <ferruh.yigit@intel.com> 
Sent: Monday, June 18, 2018 11:25 AM
To: Ido Goshen <Ido@cgstowernetworks.com>
Cc: dev@dpdk.org
Subject: Re: [PATCH 1/2] net/pcap: multiple queues fix

On 6/16/2018 4:36 PM, ido goshen wrote:
> Change open_rx/tx_pcap/iface functions to open only a single 
> pcap/dumper and not loop num_of_queue times The num_of_queue loop is 
> already acheived by the caller rte_kvargs_process

You are right, thanks for fixing this, a few comments below.

> 
> Fixes:
> 1. Opens N requested pcaps/dumpers instead of N^2 2. Leak of 
> pcap/dumper's which are being overwritten by
>    the sequential calls to open_rx/tx_pcap/iface functions 3. Use the 
> filename/iface args per queue and not just the last one
>    that overwrites the previous names

Please add a "Fixes: xx" line, that is to trace initial commit the issue introduced. More details in contribution guide.
Also please add "Cc: stable@dpdk.org" to be sure patch sent to stable tree too and to help stable tree maintainers"
[ido] as far as I can trace back this is from day one (4c17330 pcap: add new driver), Would "Fixes: 4c17330" be ok?

> 
> Signed-off-by: ido goshen <ido@cgstowernetworks.com>

<...>

> @@ -958,15 +950,8 @@ struct pmd_devargs {
>  	 * We check whether we want to open a RX stream from a real NIC or a
>  	 * pcap file
>  	 */
> -	pcaps.num_of_queue = rte_kvargs_count(kvlist, ETH_PCAP_RX_PCAP_ARG);
> -	if (pcaps.num_of_queue)
> -		is_rx_pcap = 1;
> -	else
> -		pcaps.num_of_queue = rte_kvargs_count(kvlist,
> -				ETH_PCAP_RX_IFACE_ARG);
> -
> -	if (pcaps.num_of_queue > RTE_PMD_PCAP_MAX_QUEUES)
> -		pcaps.num_of_queue = RTE_PMD_PCAP_MAX_QUEUES;
> +	is_rx_pcap = rte_kvargs_count(kvlist, ETH_PCAP_RX_PCAP_ARG) ? 1 : 0;
> +	pcaps.num_of_queue = 0;
>  
>  	if (is_rx_pcap)
>  		ret = rte_kvargs_process(kvlist, ETH_PCAP_RX_PCAP_ARG, @@ -975,6 
> +960,10 @@ struct pmd_devargs {
>  		ret = rte_kvargs_process(kvlist, ETH_PCAP_RX_IFACE_ARG,
>  				&open_rx_iface, &pcaps);
>  
> +	if (pcaps.num_of_queue > RTE_PMD_PCAP_MAX_QUEUES)
> +		pcaps.num_of_queue = RTE_PMD_PCAP_MAX_QUEUES;

Here is late for this check. You may be already access to rx->queue[],
tx->queue[] out of boundary at this point.

You should either check this value before rte_kvargs_process(), via rte_kvargs_count(), OR you should add this check into callback functions.
[ido] good catch  - will fix that

>  	if (ret < 0)
>  		goto free_kvlist;
>  
> @@ -982,15 +971,8 @@ struct pmd_devargs {
>  	 * We check whether we want to open a TX stream to a real NIC or a
>  	 * pcap file
>  	 */
> -	dumpers.num_of_queue = rte_kvargs_count(kvlist, ETH_PCAP_TX_PCAP_ARG);
> -	if (dumpers.num_of_queue)
> -		is_tx_pcap = 1;
> -	else
> -		dumpers.num_of_queue = rte_kvargs_count(kvlist,
> -				ETH_PCAP_TX_IFACE_ARG);
> -
> -	if (dumpers.num_of_queue > RTE_PMD_PCAP_MAX_QUEUES)
> -		dumpers.num_of_queue = RTE_PMD_PCAP_MAX_QUEUES;
> +	is_tx_pcap = rte_kvargs_count(kvlist, ETH_PCAP_TX_PCAP_ARG) ? 1 : 0;

Is "is_rx_pcap" or "is_tx_pcap" flags really required? Is there anything preventing have a mixture of interface and pcap in multi queue case? With the changes you are doing, I guess we can remove these checks and call following
sequentially:
rte_kvargs_process(kvlist, ETH_PCAP_RX_PCAP_ARG..) rte_kvargs_process(kvlist, ETH_PCAP_RX_IFACE_ARG ..) What do you think?
[ido] nice idea - will test if they can co-exist

But please be sure the fix and refactor patches are separate, so that fix patch can be backported to stable trees. But refactor patches won't be backported.