Re: [PATCH v4] net/netvsc: fix number Tx queues > Rx queues

[Ferruh Yigit <ferruh.yigit@amd.com>]

On 5/1/2024 8:43 AM, Morten Brørup wrote:
>> From: Alan Elder [mailto:alan.elder@microsoft.com]
>> Sent: Monday, 15 April 2024 16.41
>>
>> The previous code allowed the number of Tx queues to be set higher than the
>> number of Rx queues.  If a packet was sent on a Tx queue with index
>>> = number Rx queues there was a segfault due to accessing beyond the end of
>> the dev->data->rx_queues[] array.
>>
>> #0 rte_spinlock_trylock (sl = invalid address) at /include/rte_spinlock.h L63
>> #1  hn_process_events at /drivers/net/netvsc/hn_rxtx.c L 1129
>> #2  hn_xmit_pkts at /drivers/net/netvsc/hn_rxtx.c L1553
>>
>> This commit fixes the issue by creating an Rx queue for every Tx queue meaning
>> that an event buffer is allocated to handle receiving Tx completion messages.
>>
>> mbuf pool and Rx ring are not allocated for these additional Rx queues and RSS
>> configuration ensures that no packets are received on them.
>>
>> Fixes: 4e9c73e96e83 ("net/netvsc: add Hyper-V network device")
>> Cc: sthemmin@microsoft.com
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Alan Elder <alan.elder@microsoft.com>
>> ---
> 
> Is there any requirements to the order the application must call rte_eth_rx_queue_setup() and rte_eth_tx_queue_setup()?
> 
> I.e. does it work if rte_eth_tx_queue_setup() is called before rte_eth_rx_queue_setup(), and in the opposite order?
> 
> 
> Although the ethdev documentation says:
> 
> "The functions exported by the application Ethernet API to setup a device designated by its port identifier must be invoked in the following order:
> 
> rte_eth_dev_configure()
> rte_eth_tx_queue_setup()
> rte_eth_rx_queue_setup()
> rte_eth_dev_start()",
> 
> I would assume the order of calling rte_eth_tx_queue_setup() and rte_eth_rx_queue_setup() doesn't matter.
> 

Same, I am not aware of any strict ordering requirement for Rx and Tx
queues setup.

> 
> And the rte_eth_dev_reset() function documentation has rx/tx queue setup in the opposite order:
> 
> "After calling rte_eth_dev_reset(), the application should use rte_eth_dev_configure(), rte_eth_rx_queue_setup(), rte_eth_tx_queue_setup(), and rte_eth_dev_start() to reconfigure the device as appropriate."
>