Subject: Re: [PATCH 7/7] bnx2x: expose HW RX VLAN stripping toggle

From: Michal Schmidt <[email-masked]>
Date: Tue, 30 Aug 2011 21:30:11 +0200

On 08/30/2011 08:27 PM, Michał Mirosław wrote:
> It seems rather convoluted and unnecessary that you mirror
> NETIF_F_HW_VLAN_RX in bp->flags

This mirroring is for the benefit of functions called indirectly from 
bnx2x_set_features(). They cannot look at dev->features for 
NETIF_F_HW_VLAN_RX because it's not set before ->ndo_set_features() returns.

> and then also in fp->flags.  Are the
> fp->flags strictly mirroring hardware state (as in: there is no way
> the states can differ in any point in time where the flags are
> tested)?

Yes. This is the purpose of the second mirroring of the flag.

> For this to be true, the two functions above need to be
> called only without releasing a lock between them that is also taken
> by receive handler.

The flag propagates from bp->flags to fp->flags between unloading and 
reloading the NIC. The receive handler cannot run at the time.

> Isn't there a flag in the rx descriptor of a
> packet that says if VLAN was stripped? (All that flag keeping would be
> unnecessary then.)

There is no such flag, AFAIK.

Michal