Re: [PATCH][next] IB/rdmavt: Use struct_size() helper

[Dennis Dalessandro]

On 5/29/2019 11:12 AM, Gustavo A. R. Silva wrote:
> Make use of the struct_size() helper instead of an open-coded version
> in order to avoid any potential type mistakes, in particular in the
> context in which this code is being used.
>
> So, replace the following form:
>
> sizeof(struct rvt_sge) * init_attr->cap.max_send_sge + sizeof(struct rvt_swqe)
>
> with:
>
> struct_size(swq, sg_list, init_attr->cap.max_send_sge)
>
> and so on...
>
> Also, notice that variable size is unnecessary, hence it is removed.
>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
> ---
>   drivers/infiniband/sw/rdmavt/qp.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/infiniband/sw/rdmavt/qp.c b/drivers/infiniband/sw/rdmavt/qp.c
> index 31a2e65e4906..a60f5faea198 100644
> --- a/drivers/infiniband/sw/rdmavt/qp.c
> +++ b/drivers/infiniband/sw/rdmavt/qp.c
> @@ -988,9 +988,7 @@ struct ib_qp *rvt_create_qp(struct ib_pd *ibpd,
>   	case IB_QPT_UC:
>   	case IB_QPT_RC:
>   	case IB_QPT_UD:
> -		sz = sizeof(struct rvt_sge) *
> -			init_attr->cap.max_send_sge +
> -			sizeof(struct rvt_swqe);
> +		sz = struct_size(swq, sg_list, init_attr->cap.max_send_sge);
>   		swq = vzalloc_node(array_size(sz, sqsize), rdi->dparms.node);
>   		if (!swq)
>   			return ERR_PTR(-ENOMEM);

Looks correct, I don't think this makes the code easier to read though. 
The macro name "struct_size" is misleading to me. Maybe that's just me, 
and in any case...

Reviewed-by: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxx>