Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935221Ab2JaI72 (ORCPT ); Wed, 31 Oct 2012 04:59:28 -0400 Received: from eusmtp01.atmel.com ([212.144.249.242]:13701 "EHLO eusmtp01.atmel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934894Ab2JaI7Y (ORCPT ); Wed, 31 Oct 2012 04:59:24 -0400 Message-ID: <5090F67C.9020104@atmel.com> Date: Wed, 31 Oct 2012 10:59:24 +0100 From: Nicolas Ferre Organization: atmel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121028 Thunderbird/16.0.2 MIME-Version: 1.0 To: =?ISO-8859-1?Q?H=E5vard_Skinnemoen?= , David Laight CC: , , , , , , , Subject: Re: [PATCH v3 06/10] net/macb: clean up ring buffer logic References: <75eb5df193c504e68ebff7d6a6a88d9a1cc678cb.1351591858.git.nicolas.ferre@atmel.com> In-Reply-To: X-Enigmail-Version: 1.4.5 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.161.30.18] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1029 Lines: 28 On 10/30/2012 07:22 PM, H?vard Skinnemoen : > On Tue, Oct 30, 2012 at 4:12 AM, David Laight wrote: >>> Instead of masking head and tail every time we increment them, just let them >>> wrap through UINT_MAX and mask them when subscripting. Add simple accessor >>> functions to do the subscripting properly to minimize the chances of messing >>> this up. >> ... >>> +static unsigned int macb_tx_ring_avail(struct macb *bp) >>> +{ >>> + return TX_RING_SIZE - (bp->tx_head - bp->tx_tail); >>> +} >> >> That one doesn't look quite right to me. >> Surely it should be masking with 'TX_RING_SIZE - 1' > > Why is that? head and tail can never be more than TX_RING_SIZE apart, > so it shouldn't make any difference. Absolutely. Best regards, -- Nicolas Ferre -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/