> -----Original Message-----
> From: Stephen Hemminger <[email protected]>
> Sent: Thursday, 20 February 2025 20:33
> To: Shani Peretz <[email protected]>
> Cc: [email protected]; Tyler Retzlaff <[email protected]>; Parav Pandit
> <[email protected]>; Xueming Li <[email protected]>; Nipun Gupta
> <[email protected]>; Nikhil Agarwal <[email protected]>; Hemant
> Agrawal <[email protected]>; Sachin Saxena
> <[email protected]>; Rosen Xu <[email protected]>; Chenbo Xia
> <[email protected]>; Tomasz Duszynski <[email protected]>;
> Chengwen Feng <[email protected]>; NBU-Contact-longli
> (EXTERNAL) <[email protected]>; Wei Hu <[email protected]>; Bruce
> Richardson <[email protected]>; Kevin Laatz
> <[email protected]>; Jan Blunck <[email protected]>
> Subject: Re: [PATCH v7 2/4] lib: fix comparison between devices
>
> External email: Use caution opening links or attachments
>
>
> On Wed, 12 Feb 2025 18:38:33 +0200
> Shani Peretz <[email protected]> wrote:
>
> > DPDK supports multiple formats for specifying buses, (such as
> > "0000:08:00.0" and "08:00.0" for PCI).
> > This flexibility can lead to inconsistencies when using one format
> > while running testpmd, then attempts to use the other format in a
> > later command, resulting in a failure.
> >
> > The issue arises from the find_device function, which compares the
> > user-provided string directly with the device->name in the rte_device
> > structure.
> > If we want to accurately compare these names, we'll need to bring both
> > sides to the same representation by invoking the parse function on the
> > user input.
>
> Could you give an example where this happens please?
> Shouldn't find_device string always be changed into canonical form in
> find_device handler?
The flow I was dealing with was attach_port -> rte_dev_probe - >
local_dev_probe -> find_device.
The string passed to attach_port was the short version, directly from the user.
So, to clarify - you're saying that find_device simply need to accept the
string in its canonical form? Which means we'll only need to fix
local_dev_probe to bring it to the canonical form before calling find_device?
I tried it but then I noticed that there's no function that gets the
user-provided string and returns it's string canonical form. The closest to
this is parse, but what it eventually returns is not necessarily a string - it
can be anything - for instance pci_parse will give you back a struct
rte_pci_addr.
>
> > The proposed solution is to utilize the parse function implemented by
> > each bus. When comparing names, we will call parse on the supplied
> > string as well as on the device name itself and compare the results.
> > As part of the change the parse function will now recive the address
> > to write to and the size of the pointer, in addition it will return
> > the size of the parsed address.
>
> This leads to more complexity than needed, the layering here is a bit of a
> mess
> already. Way too complex as it is.
> There is complex nesting between generic bus code, pci bus code, kvargs
> processing and drivers.
>
> Why does the PCI code need to be calling generic code for parse.
>
>
> > This will allow consistent comparisons between different
> > representations of same devices.
>
> Not a fan of how wide this change ends up being. Would like to keep it just to
> PCI.
I agree it became too wide.
As I see it we have 3 options:
1. Add a function that returns the canonical form string of a device
and call it before find_device is called (in local_dev_probe for example)
2. Add a comparison function, pci bus will call this specific
comparison (something like what I did in here
https://patches.dpdk.org/project/dpdk/patch/[email protected]/)
3. The current proposal
What do you think?
Thanks for your help, and sorry for the late response
