On Jan 30, 2017, at 8:38 AM, Pascal Mazon [off-list ref] wrote:

On 01/30/2017 12:00 PM, Ferruh Yigit wrote:> On 1/29/2017 2:12 AM, Keith Wiles wrote:

quoted

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The tap driver setup both rx and tx file descriptors when the
rte_eth_rx_queue_setup() causing the tx to be closed when tx setup
was called.

Can you please describe the problem more.
Without this patch rx->fd == tx->fd, with this patch rx and tx has
different file descriptors.

What was the wrong with rx and tx having same fd?

As far as I can see, rte_eth_rx_queue_setup() won't close tx->fd, that
function will do nothing if rx or tx has valid fd.

quoted

Signed-off-by: Keith Wiles <redacted>

<...>

Hi,

The tap PMD recently broke for me because of this patch [1].

During init (eth_dev_tap_create()), the tap PMD allocates a shared RX/TX queue through tun_alloc().
The recent patch now releases existing queues in rx_queue_setup(), before adding new ones.

When rx_queue_setup() is called, it uses close() calls on all shared queues, effectively deleting the netdevice.
That's the main issue here.

I tested Keith's patch [2], and it fixes that issue, using separate queues.

There is however a couple of other queues-related issues in the tap PMD, but I'm not sure how to address them properly:

1. internals->fds[] gets filled only with RX queues (appart from index 0 that is common to both RX and TX).
  It means that RX queues only will be deleted when calling rte_pmd_tap_remove() or tap_tx_queue_release().

2. tap_dev_stop() is not symmetrical with tap_dev_start(): queues won't get re-created after a stop.

It may be best to keep the very first fd (created with tun_alloc() in eth_dev_tap_create() during probe) apart.
And then add separate TX/RX queues in internals->txq[] and internals->rxq[] respectively.
What do you think?

[1] d00d7cc88335 ("ethdev: release queue before setting up")
[2] http://dpdk.org/ml/archives/dev/2017-January/056470.html

Lets keep the current patch just to get over the current problem if everyone agrees. I will address the comments Pascal brings up as a later updated to the TAP PMD or I can try to get the other issues cleaned up.

-- 
Pascal Mazon
www.6wind.com

Regards,
Keith