[PATCH 1/2] drbd: fix rdma dependency

[Christoph Böhmwalder]

Am 18.03.26 um 16:31 schrieb Arnd Bergmann:
> On Wed, Mar 18, 2026, at 16:24, Christoph Böhmwalder wrote:
>> Am 18.03.26 um 11:48 schrieb Arnd Bergmann:
>>
>> Seems like we raced here, I already (supposedly?) fixed this on the
>> drbd-next branch.
> 
> Ok, I assume that will be in linux-next

Correct, should land there today.

> 
>> My fix is this Kconfig:
>>
>> config BLK_DEV_DRBD_RDMA
>> 	tristate "DRBD RDMA transport"
>> 	depends on BLK_DEV_DRBD && INFINIBAND_ADDR_TRANS
>> 	help
>>
>> 	  RDMA transport support for DRBD. This enables DRBD replication
>> 	  over RDMA-capable networks for lower latency and higher throughput.
>>
>> 	  If unsure, say N.
>>
>> And then just this in the Makefile:
>>
>> obj-$(CONFIG_BLK_DEV_DRBD_RDMA) += drbd_transport_rdma.o
>>
>> That should be equivalent, right?
> 
> It's close but not the same: 
> 
> - INFINIBAND_ADDR_TRANS is a 'bool' symbol that can still be =y
>   when CONFIG_INFINIBAND=m, so you'd still fail to build
>   BLK_DEV_DRBD_RDMA. You still need a dependency on INFINIBAND
>   (the tristate symbol) itself, though you probably also
>   need the INFINIBAND_ADDR_TRANS one that I missed
> 
> - I incorrectly assumed from the earlier Makefile logic
>   that the rdma transport exports symbols that are used
>   by the common drbd code, but I now see that the opposite
>   is the case. The difference is that for the case of
>   BLK_DEV_DRBD=y, CONFIG_INFINIBAND=m, my version force-disabled
>   the RDMA transport, while it should be in a loadable module.
> 
> It seems both versions are wrong then, but just adding
> 'depends on INFINIBAND' on top of yours should fix it.

Yes, ADDR_TRANS is needed because we need the infiniband "cm"
infrastructure (for rdma_connect et al).
Right, I did not catch that we need CONFIG_INFINIBAND separately as
well, but that seems logical.
I applied the combined fix now.

Thanks,
Christoph

-- 
Christoph Böhmwalder
LINBIT | Keeping the Digital World Running
DRBD HA —  Disaster Recovery — Software defined Storage