netdev - Re: [PATCH net 1/4] net:ethernet:aquantia: Setup max

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Date:   Thu, 21 Sep 2017 17:36:19 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Igor Russkikh <igor.russkikh@...antia.com>
Cc:     "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        David Arcari <darcari@...hat.com>,
        Pavel Belous <Pavel.Belous@...antia.com>,
        Nadezhda Krupnina <Nadezhda.Krupnina@...antia.com>,
        Simon Edelhaus <simon.edelhaus@...antia.com>
Subject: Re: [PATCH net 1/4] net:ethernet:aquantia: Setup max_mtu in ndev to
 enable jumbo frames

> @@ -283,6 +282,8 @@ int aq_nic_ndev_init(struct aq_nic_s *self)
>  	self->ndev->features = aq_hw_caps->hw_features;
>  	self->ndev->priv_flags = aq_hw_caps->hw_priv_flags;
>  	self->ndev->mtu = aq_nic_cfg->mtu - ETH_HLEN;
> +	self->ndev->min_mtu = ETH_MIN_MTU;

This is not required. It will default to ETH_MIN_MTU.

     Andrew

> +	self->ndev->max_mtu = self->aq_hw_caps.mtu - ETH_FCS_LEN - ETH_HLEN;
>  
>  	return 0;
>  }
> @@ -695,7 +696,7 @@ int aq_nic_set_mtu(struct aq_nic_s *self, int new_mtu)
>  {
>  	int err = 0;
>  
> -	if (new_mtu > self->aq_hw_caps.mtu) {
> +	if (new_mtu + ETH_FCS_LEN > self->aq_hw_caps.mtu) {

If you have set max_mtu correctly, this cannot happen.  But it seems
odd you don't have ETH_HLEN here, where as when setting max_mtu you
do.

   Andrew