Re: [GIT] Networking

[David Miller]

From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Date: Wed, 1 May 2013 21:55:38 -0700

> I think the positions of those bits matter, and adding
> NETIF_F_HW_VLAN_STAG_*_BIT randomly in the middle broke things. That's
> backed up by the fact that we have things like
> 
>       __UNUSED_NETIF_F_1
> 
> and
> 
>           /**/NETIF_F_GSO_SHIFT,          /* keep the order of SKB_GSO_* bits */
>         NETIF_F_TSO_BIT                 /* ... TCPv4 segmentation */
>                 = NETIF_F_GSO_SHIFT,
> 
> in that array. There is some ordering, and there is some meaning to
> the bit numbers, and adding the *_STAG_* bits in the middle broke some
> subtle dependency.

The other thing this does is it pushes some bits past bit 31.

netdev_features_t, which holds these masks, is 64-bit but we've
already seen one place in a driver where a 32-bit value was being
used.

I'll look more deeply into this, thanks.
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