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SubjectRe: [PATCH] drivers/net/usb/asix: resync from vendor's copy
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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.



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