From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lord Subject: Re: [PATCH] drivers/net/usb/asix: resync from vendor's copy Date: Wed, 09 Nov 2011 12:40:13 -0500 Message-ID: <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> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: David Miller , netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Ben Hutchings Return-path: In-Reply-To: <1320859911.2781.1.camel@bwh-desktop> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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. Cheers