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