[PATCH] RDMA/ucma: fix rdma_ucm_query_ib_service_resp struct padding

[PATCH] RDMA/ucma: fix rdma_ucm_query_ib_service_resp struct padding

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

On a few 32-bit architectures, the newly added ib_user_service_rec
structure is not 64-bit aligned the way it is on most regular ones.

Add explicit padding into the rdma_ucm_query_ib_service_resp and
rdma_ucm_resolve_ib_service structures that embed it, so that the
layout is compatible across all of them.

This is an ABI change on i386, aligning it with x86_64 and the other
64-bit architectures to avoid having to use a compat ioctl handler.

Fixes: 810f874eda8e ("RDMA/ucma: Support query resolved service records")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 include/uapi/rdma/rdma_user_cm.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/uapi/rdma/rdma_user_cm.h b/include/uapi/rdma/rdma_user_cm.h
index 5ded174687ee..8e1d584f6633 100644
--- a/include/uapi/rdma/rdma_user_cm.h
+++ b/include/uapi/rdma/rdma_user_cm.h
@@ -192,6 +192,7 @@ struct rdma_ucm_query_path_resp {
 
 struct rdma_ucm_query_ib_service_resp {
 	__u32 num_service_recs;
+	__u32 :32;
 	struct ib_user_service_rec recs[];
 };
 
@@ -362,6 +363,7 @@ struct rdma_ucm_ib_service {
 
 struct rdma_ucm_resolve_ib_service {
 	__u32 id;
+	__u32 :32;
 	struct rdma_ucm_ib_service ibs;
 };
 
-- 
2.39.5

Re: [PATCH] RDMA/ucma: fix rdma_ucm_query_ib_service_resp struct padding

[Jason Gunthorpe]

On Mon, Dec 08, 2025 at 02:33:05PM +0100, Arnd Bergmann wrote:
> diff --git a/include/uapi/rdma/rdma_user_cm.h b/include/uapi/rdma/rdma_user_cm.h
> index 5ded174687ee..8e1d584f6633 100644
> --- a/include/uapi/rdma/rdma_user_cm.h
> +++ b/include/uapi/rdma/rdma_user_cm.h
> @@ -192,6 +192,7 @@ struct rdma_ucm_query_path_resp {
>  
>  struct rdma_ucm_query_ib_service_resp {
>  	__u32 num_service_recs;
> +	__u32 :32;
>  	struct ib_user_service_rec recs[];
>  };

RDMA doesn't use bitfields here, I changed these to be reserved like
the others.

> @@ -362,6 +363,7 @@ struct rdma_ucm_ib_service {
>  
>  struct rdma_ucm_resolve_ib_service {
>  	__u32 id;
> +	__u32 :32;
>  	struct rdma_ucm_ib_service ibs;
>  };

And I added the missing

 struct rdma_ucm_ib_service {
-       __u64 service_id;
+       __aligned_u64 service_id;

Again, like the others.

Applied to for-rc thanks

Jason