From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932653Ab1KIRsV (ORCPT ); Wed, 9 Nov 2011 12:48:21 -0500 Received: from mail.solarflare.com ([216.237.3.220]:40323 "EHLO exchange.solarflare.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932574Ab1KIRsU (ORCPT ); Wed, 9 Nov 2011 12:48:20 -0500 Subject: Re: [PATCH] drivers/net/usb/asix: resync from vendor's copy From: Ben Hutchings To: Mark Lord CC: David Miller , , In-Reply-To: <4EBABAFD.6050604@teksavvy.com> References: <4EA89972.5060101@teksavvy.com> <20111026.194045.2019668159403582571.davem@davemloft.net> <4EA8B283.3010105@teksavvy.com> <20111026.221719.2216112919297458522.davem@davemloft.net> <4EB19BBE.5050602@teksavvy.com> <1320266549.2782.21.camel@bwh-desktop> <4EBAA967.10403@teksavvy.com> <1320856444.18929.78.camel@deadeye> <4EBAAEA5.1060408@teksavvy.com> <4EBAB0EA.1050102@teksavvy.com> <4EBAB643.8020603@teksavvy.com> <1320859911.2781.1.camel@bwh-desktop> <4EBABAFD.6050604@teksavvy.com> Content-Type: text/plain; charset="UTF-8" Organization: Solarflare Communications Date: Wed, 9 Nov 2011 17:48:15 +0000 Message-ID: <1320860895.2781.6.camel@bwh-desktop> MIME-Version: 1.0 X-Mailer: Evolution 2.32.2 (2.32.2-1.fc14) Content-Transfer-Encoding: 7bit X-Originating-IP: [10.17.20.137] X-TM-AS-Product-Ver: SMEX-8.0.0.1181-6.500.1024-18502.005 X-TM-AS-Result: No--21.431300-0.000000-31 X-TM-AS-User-Approved-Sender: Yes X-TM-AS-User-Blocked-Sender: No X-OriginalArrivalTime: 09 Nov 2011 17:48:20.0092 (UTC) FILETIME=[C4B893C0:01CC9F07] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2011-11-09 at 12:40 -0500, Mark Lord wrote: > On 11-11-09 12:31 PM, Ben Hutchings wrote: > > On Wed, 2011-11-09 at 12:20 -0500, Mark Lord wrote: > >> On 11-11-09 11:57 AM, Mark Lord wrote: > >>> On 11-11-09 11:47 AM, Mark Lord wrote: > >>> .. > >>>> Note: I'm looking at smsc95xx.c and smsc75xx.c for examples, > >>>> and they both have the same problem I'll have here: > >>>> > >>>> How to update the csum settings atomically. > >>>> A spinlock is no good, because config register access is over USB. > >>> > >>> Nevermind.. a slight change in the logic and all is well again. > >> .. > >> > >> Or even simpler (below). I don't think this method requires any > >> extra locking, but I'm still open to persuasion. :) > > > > Looks reasonable, but... > > > >> static int ax88772b_set_features(struct net_device *netdev, u32 features) > >> { > >> struct usbnet *dev = netdev_priv(netdev); > >> struct ax88772b_data *priv = (struct ax88772b_data *)dev->driver_priv; > >> u16 tx_csum = 0, rx_csum = 0; > >> > >> priv->features = features & (NETIF_F_HW_CSUM | NETIF_F_RXCSUM); > > > > ...why do you need priv->features at all? > > > There's code elsewhere that takes action under some conditions > based on the current setting of the NETIF_F_RXCSUM flag. > > I don't claim to fully understand what's going on, > but it doesn't care much about races on set/clear of the flag. And it can use dev->features. Ben. -- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.