Re: [PATCH rdma-next v4 02/11] IB/core: Introduce FRMR pools

[Leon Romanovsky]

On Thu, Feb 26, 2026 at 03:52:07PM +0200, Edward Srouji wrote:
> From: Michael Guralnik <michaelgur@xxxxxxxxxx>
> 
> Add a generic Fast Registration Memory Region pools mechanism to allow
> drivers to optimize memory registration performance.
> Drivers that have the ability to reuse MRs or their underlying HW
> objects can take advantage of the mechanism to keep a 'handle' for those
> objects and use them upon user request.
> We assume that to achieve this goal a driver and its HW should implement
> a modify operation for the MRs that is able to at least clear and set the
> MRs and in more advanced implementations also support changing a subset
> of the MRs properties.
> 
> The mechanism is built using an RB-tree consisting of pools, each pool
> represents a set of MR properties that are shared by all of the MRs
> residing in the pool and are unmodifiable by the vendor driver or HW.
> 
> The exposed API from ib_core to the driver has 4 operations:
> Init and cleanup - handles data structs and locks for the pools.
> Push and pop - store and retrieve 'handle' for a memory registration
> or deregistrations request.
> 
> The FRMR pools mechanism implements the logic to search the RB-tree for
> a pool with matching properties and create a new one when needed and
> requires the driver to implement creation and destruction of a 'handle'
> when pool is empty or a handle is requested or is being destroyed.
> 
> Later patch will introduce Netlink API to interact with the FRMR pools
> mechanism to allow users to both configure and track its usage.
> A vendor wishing to configure FRMR pool without exposing it or without
> exposing internal MR properties to users, should use the
> kernel_vendor_key field in the pools key. This can be useful in a few
> cases, e.g, when the FRMR handle has a vendor-specific un-modifiable
> property that the user registering the memory might not be aware of.
> 
> Signed-off-by: Michael Guralnik <michaelgur@xxxxxxxxxx>
> Reviewed-by: Yishai Hadas <yishaih@xxxxxxxxxx>
> Signed-off-by: Edward Srouji <edwards@xxxxxxxxxx>
> ---
>  drivers/infiniband/core/Makefile     |   2 +-
>  drivers/infiniband/core/frmr_pools.c | 319 +++++++++++++++++++++++++++++++++++
>  drivers/infiniband/core/frmr_pools.h |  48 ++++++
>  include/rdma/frmr_pools.h            |  37 ++++
>  include/rdma/ib_verbs.h              |   8 +
>  5 files changed, 413 insertions(+), 1 deletion(-)

<...>

> +// SPDX-License-Identifier: GPL-2.0-only

<...>

> +EXPORT_SYMBOL(ib_frmr_pools_init);

It is odd to see these two lines together. Either update the SPDX license to
'GPL-2.0 OR Linux-OpenIB', as we do for uverbs, and keep EXPORT_SYMBOL() as is,
or keep the current SPDX-License-Identifier and switch to EXPORT_SYMBOL_GPL().

Thanks