[ofa-general] Re: wmb missing in libmthca?

[Michael S. Tsirkin]

> Quoting Roland Dreier <rdreier at cisco.com>:
> Subject: Re: wmb missing in libmthca?
> 
>  > Roland, I see this in kernel:
>  > 
>  >                 ((struct mthca_next_seg *) prev_wqe)->nda_op =
>  >                         cpu_to_be32((ind << qp->rq.wqe_shift) | 1);
>  >                 wmb();
>  >                 ((struct mthca_next_seg *) prev_wqe)->ee_nds =
>  >                         cpu_to_be32(MTHCA_NEXT_DBD | size);
>  > 
>  > but userspace does not have wmb here.
>  > Is it needed?
> 
> It does seem that way -- otherwise the hardware might read prev_wqe
> and see the ee_nds field as set before the nda_op field has the right
> variable.  Does this look right to you as a libmthca fix?

Looks ok.

-- 
MST