[dpdk-dev] [dpdk-stable] [PATCH v3 1/7] ethdev: fix port data reset timing

[Ferruh Yigit]

On 4/25/2018 1:16 PM, Matan Azrad wrote:
> Hi all
> 
> From: Ferruh Yigit, Thursday, April 19, 2018 2:08 PM
>>> But rte_eth_dev_release_port() is still broken because of this change,
>>> please check _rte_eth_dev_callback_process() which uses dev->data-
>>> port_id.
> 
> The issue is that a DESTROY callback gets port_id=0 all the time, regardless the destroyed port id.
> 
> Let's discuss about the fix:
> 
> There are 2 options for the DESTROY event meaning:
> 
> 1. The device is going to be destroyed in the future (a bit after the callbacks calling).
> 	The user may think that there is a valid data in the device structure in the callback time,
> 	Thus, he may use it.
> 	The fix here is to move the callback to the start of the function,
> 	In this time the data field is still valid.
> 
> 2. The device was already destroyed in the past (a bit before the callbacks calling).
> 	The user should think that there is no any valid data in the device structure in the callback time,
> 	Thus, he doesn't use it.
> 	The issue here:
> 	_rte_eth_dev_callback_process() assumes there is a valid data in the data field  all the time,
> 	But in this case the data field is not valid because the device was already destroyed.
> 	Optional fixes:
> 	1. Always keep the data->port_id valid.
> 	2. keep the data->port_id valid only for the _rte_eth_dev_callback_process() call.
> 	2. Change _rte_eth_dev_callback_process() arg from "struct rte_eth_dev *dev" to "uint16_t port_id"
> 		a. Need to change all the calls for this internal API.
> 
> I vote to 2.1.
> 
> 
> What do you think?

What is the concern with 1? It is easy to implement.

And it may be better because if callback called after device destroyed, there is
no guarantee/locking that same port won't be re-used, in the middle of the
callback function rte_eth_dev_data can be updated, no?

> 
> Matan.
> 	
> 
> 
>