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From: Justin Lai <justinlai0215@realtek.com>
To: Andrew Lunn <andrew@lunn.ch>
CC: "kuba@kernel.org" <kuba@kernel.org>,
        "davem@davemloft.net"
	<davem@davemloft.net>,
        "edumazet@google.com" <edumazet@google.com>,
        "pabeni@redhat.com" <pabeni@redhat.com>,
        "linux-kernel@vger.kernel.org"
	<linux-kernel@vger.kernel.org>,
        "netdev@vger.kernel.org"
	<netdev@vger.kernel.org>,
        "jiri@resnulli.us" <jiri@resnulli.us>,
        "horms@kernel.org" <horms@kernel.org>,
        Ping-Ke Shih <pkshih@realtek.com>, Larry Chiu <larry.chiu@realtek.com>
Subject: RE: [PATCH net-next v18 06/13] rtase: Implement .ndo_start_xmit function
Thread-Topic: [PATCH net-next v18 06/13] rtase: Implement .ndo_start_xmit
 function
Thread-Index: AQHaoUVFS3AReltz50OiDSH+k5DKnbGQKQQAgARjhdA=
Date: Mon, 13 May 2024 03:43:52 +0000
Message-ID: <7f1ff93c4f7d4fc9bdefbb646c18acc1@realtek.com>
References: <20240508123945.201524-1-justinlai0215@realtek.com>
 <20240508123945.201524-7-justinlai0215@realtek.com>
 <1bb2d174-ccae-43e3-80ec-872b9a140fbe@lunn.ch>
In-Reply-To: <1bb2d174-ccae-43e3-80ec-872b9a140fbe@lunn.ch>
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>=20
> > +static u32 rtase_tx_csum(struct sk_buff *skb, const struct net_device
> > +*dev) {
> > +     u32 csum_cmd =3D 0;
> > +     u8 ip_protocol;
> > +
> > +     switch (vlan_get_protocol(skb)) {
> > +     case htons(ETH_P_IP):
> > +             csum_cmd =3D RTASE_TX_IPCS_C;
> > +             ip_protocol =3D ip_hdr(skb)->protocol;
> > +             break;
> > +
> > +     case htons(ETH_P_IPV6):
> > +             csum_cmd =3D RTASE_TX_IPV6F_C;
> > +             ip_protocol =3D ipv6_hdr(skb)->nexthdr;
> > +             break;
> > +
> > +     default:
> > +             ip_protocol =3D IPPROTO_RAW;
> > +             break;
> > +     }
> > +
> > +     if (ip_protocol =3D=3D IPPROTO_TCP)
> > +             csum_cmd |=3D RTASE_TX_TCPCS_C;
> > +     else if (ip_protocol =3D=3D IPPROTO_UDP)
> > +             csum_cmd |=3D RTASE_TX_UDPCS_C;
> > +     else
> > +             WARN_ON_ONCE(1);
>=20
> I'm not so sure about this WARN_ON_ONCE(). It looks like if i send a cust=
om
> packet which is not IPv4 or IPv6 it will fire. There are other protocols =
then IP.
> Connecting to an Ethernet switch using DSA tags would be a good example. =
So
> i don't think you want this warning.
>=20
>       Andrew

Hi Andrew,
The condition for entering this function is checksum_partial, which require=
s
hardware to help calculate the checksum, so protocols that are not supporte=
d
by the hardware will issue warn_on_once.