Re: [PATCH] rxe: Fix dma.length computation in wr_set_sge_list

[Jared Holzman <jholzman@nvidia.com>]

On 6/3/26 21:11, Jason Gunthorpe wrote:
> On Sun, May 31, 2026 at 03:07:21PM +0300, Jared Holzman wrote:
>> wr_set_sge_list() summed the SGE lengths with a loop that never
>> advanced sg_list:
>>
>> 	while (num_sge--)
>> 		tot_length += sg_list->length;
>>
>> so tot_length ended up as num_sge * sg_list[0].length instead of the
>> true sum, and wqe->dma.length / wqe->dma.resid were written with that
>> wrong value. The per-SGE entries themselves were unaffected because
>> they are populated by the preceding memcpy().
>>
>> The kernel rxe driver requires dma.length == sum(sge[i].length) and
>> enforces it in rxe_mr.c:copy_data(), so a multi-SGE WR posted through
>> the ibv_qp_ex builder API (ibv_wr_set_sge_list) on rxe completes with
>> IB_WC_LOC_PROT_ERR once finish_packet()/copy_data() runs off the end
>> of the SGE list.
>>
>> The legacy ibv_post_send path (init_send_wqe) is unaffected; it sums
>> the lengths with an indexed for loop.
>>
>> Fix by computing the total with an indexed loop, matching the style
>> already used in rxe_post_one_recv() and init_send_wqe() in this file.
>>
>> Fixes: 1a894ca10105 ("Providers/rxe: Implement ibv_create_qp_ex verb")
>> Signed-off-by: Jared Holzman <jholzman@nvidia.com>
>> PR: https://github.com/linux-rdma/rdma-core/pull/1744
> I don't know what this is, upstream doesn't have this code qp_ex
> support or 1a894ca10105
>
> The rdma-core thing looks OK though.
>
> Jason

It is only an rdma-core change.

The commit hash is from rdma-core repo: 
https://github.com/linux-rdma/rdma-core

Jared