From: Zhu, Lingshan <redacted>
Sent: Tuesday, July 5, 2022 12:56 PM

quoted

Both can be queried simultaneously. Each will return their own feature bits

using same attribute.

quoted

It wont lead to the race.

How? It is just a piece of memory, xxxx[attr], do you see locks in
nla_put_u64_64bit()? It is a typical race condition, data accessed by multiple
producers / consumers.

No. There is no race condition in here.
And new attribute enum by no means avoid any race.

Data put using nla_put cannot be accessed until they are transferred.

And re-use a netlink attr is really confusing.

Please put comment for this variable explaining why it is shared for the exception.

Before that lets start, can you share a real world example of when this feature bitmap will have different value than the mgmt. device bitmap value?

quoted

quoted

IMHO, I don't see any advantages of re-using this attr.

We don’t want to continue this mess of VDPA_DEV prefix for new

attributes due to previous wrong naming.
as you point out before, is is a wrong naming, we can't re-nmme it because
we don't want to break uAPI, so there needs a new attr, if you don't like the
name VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES, it is more than
welcome to suggest a new one

Thanks