Re: [PATCH v2] net: natsemi: ns83820: add checks for dma mapping error

[David Miller]

From: Alexey Khoroshilov <khoroshi...@ispras.ru>
Date: Sat, 22 Apr 2017 16:06:05 +0300

> +             free_idx = (free_idx + NR_TX_DESC - 1) % NR_TX_DESC;

This is more simply stated as "(free_idx - 1) % NR_TX_DESC.