Re: [PATCH v4] bus: fix inconsistent representation of PCI numbers

[fengchengwen <fengchengwen@huawei.com>]

On 2025/1/30 2:06, Bruce Richardson wrote:
> On Wed, Jan 29, 2025 at 09:17:38AM -0800, Stephen Hemminger wrote:
>> On Wed, 29 Jan 2025 10:54:16 +0200
>> Shani Peretz <shperetz@nvidia.com> wrote:
>>
>>> DPDK provides two formats for specifying PCI device numbers:
>>> a full version ("0000:08:00.0") and a short version ("08:00.0").
>>> Issues can occur when an application uses one format (e.g., short)
>>> while running testpmd, then attempts to use the other format
>>> (e.g., full) in a later command, resulting in a failure.
>>>
>>> The issue is that find_device goes over the list of devices and
>>> compares the user-provided string to the rte_device structure's
>>> device->name (device->name is just the string received from devargs
>>> (i.e "08:00.0" or "0000:08:00.0")).
>>> Notice that there's another field that represents the device name,
>>> but this one is in the rte_pci_bus struct. This name is actually the result
>>> of the PCI parse function ("0000:08:00.0").
>>> 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.
>>>
>>> To make the cmp_dev_name function applicable to all buses—not just PCI—
>>> 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.
>>> This will allow consistent comparisons between different representations
>>> of same devices.
>>>
>>> Also, the pci_common_set function has been modified to improve naming
>>> consistency for PCI buses.
>>> Now, the name stored in rte_device for PCI buses will match the parsed
>>> name that is also stored in rte_pci_device name,
>>> rather than using the user-provided string from devargs.
>>> As a result, when a new PCI device is registered, the name displayed in
>>> the device list will be the parsed version.
>>>
>>> Added tests that compare and find devices in various forms of names
>>> under test_devargs.
>>>
>>> Fixes: a3ee360f4440 ("eal: add hotplug add/remove device")
>>
>> Maybe just fix for now by normalizing the PCI device string when before
>> storing and after parsing?  That would allow for simple fix that can be backported.
>> The more complex generalization of bus address is too much to go to stable branch.

+1

> 
> One idea for backport, perhaps?
> 
> https://patches.dpdk.org/project/dpdk/patch/20241119155723.2307189-1-bruce.richardson@intel.com/

ack

>