netdev - Re: [RFCv7 PATCH net-next 02/36] net: replace general features macroes with global netdev

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Date:   Thu, 11 Aug 2022 13:05:29 +0200
From:   Alexander Lobakin <alexandr.lobakin@...el.com>
To:     "shenjian (K)" <shenjian15@...wei.com>
Cc:     Alexander Lobakin <alexandr.lobakin@...el.com>,
        davem@...emloft.net, kuba@...nel.org, andrew@...n.ch,
        ecree.xilinx@...il.com, hkallweit1@...il.com, saeed@...nel.org,
        leon@...nel.org, netdev@...r.kernel.org, linuxarm@...neuler.org
Subject: Re: [RFCv7 PATCH net-next 02/36] net: replace general features macroes with global netdev_features variables

From: "shenjian (K)" <shenjian15@...wei.com>
Date: Wed, 10 Aug 2022 20:01:15 +0800

> 在 2022/8/10 17:58, Alexander Lobakin 写道:
> > From: Jian Shen <shenjian15@...wei.com>
> > Date: Wed, 10 Aug 2022 11:05:50 +0800
> >
> >> There are many netdev_features bits group used in kernel. The definition
> >> will be illegal when using feature bit more than 64. Replace these macroes
> >> with global netdev_features variables, initialize them when netdev module
> >> init.
> >>
> >> Signed-off-by: Jian Shen <shenjian15@...wei.com>
> >> ---

[...]

> >> @@ -11362,6 +11363,86 @@ static struct pernet_operations __net_initdata default_device_ops = {
> >>   	.exit_batch = default_device_exit_batch,
> >>   };
> >>   
> >> +static void __init netdev_features_init(void)
> > Given that you're creating a new file dedicated to netdev features,
> > I'd place that initializer there. You can then declare its proto in
> > net/core/dev.h.
> I want to make sure it cann't be called outside net/core/dev.c, for some
> drivers include net/core/dev.h, then they can see it.

net/core/dev.h is internal, nobody outside net/core/ uses it and
this was its purpose.

> 
> >> +{
> >> +	netdev_features_t features;
> >> +
> >> +	netdev_features_set_array(&netif_f_ip_csum_feature_set,
> >> +				  &netdev_ip_csum_features);
> >> +	netdev_features_set_array(&netif_f_csum_feature_set_mask,
> >> +				  &netdev_csum_features_mask);
> >> +
> >> +	netdev_features_set_array(&netif_f_gso_feature_set_mask,
> >> +				  &netdev_gso_features_mask);
> >> +	netdev_features_set_array(&netif_f_general_tso_feature_set,
> >> +				  &netdev_general_tso_features);
> >> +	netdev_features_set_array(&netif_f_all_tso_feature_set,
> >> +				  &netdev_all_tso_features);
> >> +	netdev_features_set_array(&netif_f_tso_ecn_feature_set,
> >> +				  &netdev_tso_ecn_features);
> >> +	netdev_features_set_array(&netif_f_all_fcoe_feature_set,
> >> +				  &netdev_all_fcoe_features);
> >> +	netdev_features_set_array(&netif_f_gso_soft_feature_set,
> >> +				  &netdev_gso_software_features);
> >> +	netdev_features_set_array(&netif_f_gso_encap_feature_set,
> >> +				  &netdev_gso_encap_all_features);
> >> +
> >> +	netdev_csum_gso_features_mask =
> >> +		netdev_features_or(netdev_gso_features_mask,
> >> +				   netdev_csum_features_mask);
> > (I forgot to mention this in 01/36 ._.)
> >
> > As you're converting to bitmaps, you should probably avoid direct
> > assignments. All the bitmap_*() modification functions take a pointer
> > to the destination as a first argument. So it should be
> >
> > netdev_features_or(netdev_features_t *dst, const netdev_features_t *src1,
> > 		   const netdev_features_t *src1);
> The netdev_features_t will be convert to a structure which only contained
> a feature bitmap. So assginement is ok.

Yeah I realized it later, probably a good idea.

> 
> 
> >> +
> >> +	netdev_features_set_array(&netif_f_one_for_all_feature_set,
> >> +				  &netdev_one_for_all_features);
> > Does it make sense to prefix features and the corresponding sets
> > differently? Why not just 'netdev_' for both of them?
> For all the feature bits are named "NETFI_F_XXX_BIT",

Right, but then why are netdev_*_features prefixed with 'netdev',
not 'netif_f'? :D Those sets are tied tightly with the feature
structures, so I think they should have the same prefix. I'd go
with 'netdev' for both.

> 
> 
> >> +	netdev_features_set_array(&netif_f_all_for_all_feature_set,
> >> +				  &netdev_all_for_all_features);

[...]

> >> -- 
> >> 2.33.0
> > Thanks,
> > Olek
> >
> > .
> 
> Thank,
> Jian

Thanks,
Olek