Re: [PATCH rdma-next v4 00/16] RDMA: Introduce generic buffer descriptor infrastructure for umem

[Jiri Pirko <jiri@resnulli.us>]

Sun, May 17, 2026 at 01:47:55PM +0200, leon@kernel.org wrote:
>On Tue, May 12, 2026 at 04:23:19PM -0300, Jason Gunthorpe wrote:
>> On Thu, May 07, 2026 at 02:52:15PM +0200, Jiri Pirko wrote:
>> > From: Jiri Pirko <jiri@nvidia.com>
>> > 
>> > This patchset introduces a generic buffer descriptor infrastructure
>> > for passing memory buffers (dma-buf or user VA) to uverbs commands,
>> > and wires it up for CQ and QP creation in the uverbs core, efa, mlx5,
>> > bnxt_re and mlx4 drivers.
>> > 
>> > Instead of adding ad-hoc per-buffer UAPI attributes for each new buffer
>> > type, each command declares dedicated UVERBS_ATTR_UMEM attributes that
>> > carry one buffer descriptor each. Each descriptor specifies a buffer
>> > type, covering both VA and dma-buf. A consumption check ensures
>> > userspace and driver agree on which attributes are used.
>> > 
>> > The patchset:
>> > 1-2,4. Plumbing: rename ib_umem_get() to ib_umem_get_va() and re-route
>> >    it through the new central ib_umem_get(); no behaviour change.
>> > 3. Introduces the core buffer descriptor infrastructure and UAPI.
>> > 5. Inlines the const attr helpers so ib_core can use them.
>> > 6. Factors out CQ buffer umem processing into a helper.
>> > 7. Adds the CQ buffer UMEM attribute and driver wrappers.
>> > 8-11. Converts efa, mlx5, bnxt_re and mlx4 to use the new CQ helpers,
>> >    with drivers taking umem ownership.
>> > 12. Removes the legacy umem field from struct ib_cq, now that all
>> >    drivers use the new helpers.
>> > 13. Adds optional whole-QP, RQ and SQ UMEM attributes to QP creation.
>> > 14. Converts mlx5 QP creation to use the new attributes.
>> > 15-16. Adds mlx5 driver-namespace UMEM attributes for CQ and QP
>> >    doorbell records.
>> 
>> I think it is OK looking, Leon?
>
>I have a strange feeling that we have too many ib_umem_get_*()
>functions. For example ib_umem_get_cq_buf() which doesn't accept
>anything CQ specific. Or this general ib_umem_get_attr_or_va().

Does not accept anything CQ-specific, but internally it works with CQ
attributes. That's why.