Re: [dpdk-dev] [PATCH 2/5] ethdev: add port ownership

[Thomas Monjalon <thomas@monjalon.net>]

Hi,

I will give my view on locking and synchronization in a different email.
Let's discuss about the API here.

05/12/2017 12:12, Ananyev, Konstantin:
> From: Matan Azrad [mailto:matan@mellanox.com]
> > From: Ananyev, Konstantin [mailto:konstantin.ananyev@intel.com]

> > > If the goal is just to have an ability to recognize is that device is managed by
> > > another device (failsafe, bonding, etc.),  then I think all we need is a pointer
> > > to rte_eth_dev_data of the owner (NULL would mean no owner).
> > 
> > I think string is better than a pointer from the next reasons:
> > 1. It is more human friendly than pointers for debug and printing.
> 
> We can have a function that would take an owner pointer and produce nice
> pretty formatted text explanation: "owned by fail-safe device at port X" or so.

I don't think it is possible or convenient to have such function.
Keep in mind that the owner can be an application thread.
If you prefer using a single function pointer (may help for
atomic implementation), we can allocate an owner structure containing
a name as a string to identify the owner in human readable format.
Then we just have to set the pointer of this struct to rte_eth_dev_data.


> What I meant - this api to set/get ownership should be sort of internal to ethdev layer.
> Let say it would be used for failsafe/bonding (any other compound) device that needs
> to own/manage several low-level devices.
> So in normal situation user wouldn't need to use that API directly at all.

Again, the application may use this API to declare its ownership.
And anwyway, it may be interesting from an application point of view
to be able to list every devices and their internal owners.