Subject: Re: [PATCH rdma-next 3/3] RDMA/rw: Support threshold for registration vs scattering to local pages

From: Christoph Hellwig <[email-masked]>
Date: Sun, 6 Oct 2019 23:58:25 -0700

>  /*
> - * Check if the device might use memory registration.  This is currently only
> - * true for iWarp devices. In the future we can hopefully fine tune this based
> - * on HCA driver input.
> + * Check if the device might use memory registration.
>   */

Please keep the important bits of this comments instead of just
removing them.

>  {
> @@ -30,6 +28,8 @@ static inline bool rdma_rw_can_use_mr(struct ib_device *dev, u8 port_num)
>  		return true;
>  	if (unlikely(rdma_rw_force_mr))
>  		return true;
> +	if (dev->attrs.max_sgl_rd)
> +		return true;

Logically this should go before the rdma_rw_force_mr check.

>  	if (unlikely(rdma_rw_force_mr))
>  		return true;
> +	if (dev->attrs.max_sgl_rd && dir == DMA_FROM_DEVICE
> +	    && dma_nents > dev->attrs.max_sgl_rd)

Wrong indendation.  The && belongs on the first line.  And again, this
logically belongs before the rdma_rw_force_mr check.