Re: [PATCH 1/1] net: rds: add service level support in rds-info

[Doug Ledford <dledford@redhat.com>]

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On Mon, 2019-08-19 at 20:52 -0400, Zhu Yanjun wrote:
> diff --git a/include/uapi/linux/rds.h b/include/uapi/linux/rds.h
> index fd6b5f6..cba368e 100644
> --- a/include/uapi/linux/rds.h
> +++ b/include/uapi/linux/rds.h
> @@ -250,6 +250,7 @@ struct rds_info_rdma_connection {
>         __u32           rdma_mr_max;
>         __u32           rdma_mr_size;
>         __u8            tos;
> +       __u8            sl;
>         __u32           cache_allocs;
>  };
>  
> @@ -265,6 +266,7 @@ struct rds6_info_rdma_connection {
>         __u32           rdma_mr_max;
>         __u32           rdma_mr_size;
>         __u8            tos;
> +       __u8            sl;
>         __u32           cache_allocs;
>  };
>  

This is a user space API break (as was the prior patch mentioned
below)...

> The commit fe3475af3bdf ("net: rds: add per rds connection cache
> statistics") adds cache_allocs in struct rds_info_rdma_connection
> as below:
> struct rds_info_rdma_connection {
> ...
>         __u32           rdma_mr_max;
>         __u32           rdma_mr_size;
>         __u8            tos;
>         __u32           cache_allocs;
>  };
> The peer struct in rds-tools of struct rds_info_rdma_connection is as
> below:
> struct rds_info_rdma_connection {
> ...
>         uint32_t        rdma_mr_max;
>         uint32_t        rdma_mr_size;
>         uint8_t         tos;
>         uint8_t         sl;
>         uint32_t        cache_allocs;
> };

Why are the user space rds tools not using the kernel provided abi
files?

In order to know if this ABI breakage is safe, we need to know what
versions of rds-tools are out in the wild and have their own headers
that we need to match up with.  Are there any versions of rds-tools that
actually use the kernel provided headers?  Are there any other users of
uapi/linux/rds.h besides rds-tools?

Once the kernel and rds-tools package are in sync, rds-tools needs to be
modified to use the kernel header and proper ABI maintenance needs to be
started.

-- 
Doug Ledford <dledford@redhat.com>
    GPG KeyID: B826A3330E572FDD
    Fingerprint = AE6B 1BDA 122B 23B4 265B  1274 B826 A333 0E57 2FDD

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