Messages in this thread | | | Date | Wed, 09 Nov 2011 12:40:13 -0500 | From | Mark Lord <> | Subject | Re: [PATCH] drivers/net/usb/asix: resync from vendor's copy |
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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
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