From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marek Vasut <marex@denx.de>
Subject: Re: [PATCH V2 2/3] net: dsa: ksz: Factor out common tag code
Date: Fri, 14 Dec 2018 14:30:35 +0100
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References: <20181213160159.18956-1-marex@denx.de>
 <20181213160159.18956-3-marex@denx.de> <20181214090525.GA5513@lunn.ch>
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Cc: netdev@vger.kernel.org, f.fainelli@gmail.com,
        Tristram Ha <Tristram.Ha@microchip.com>,
        Vivien Didelot <vivien.didelot@savoirfairelinux.com>,
        Woojung Huh <woojung.huh@microchip.com>,
        "David S . Miller" <davem@davemloft.net>
To: Andrew Lunn <andrew@lunn.ch>
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On 12/14/2018 10:05 AM, Andrew Lunn wrote:
>> +static struct sk_buff *ksz_common_xmit(struct sk_buff *skb,
>> +				       struct net_device *dev, int len)
>>  {
>> -	struct dsa_port *dp = dsa_slave_to_port(dev);
>>  	struct sk_buff *nskb;
>>  	int padlen;
>> -	u8 *tag;
>>  
>>  	padlen = (skb->len >= ETH_ZLEN) ? 0 : ETH_ZLEN - skb->len;
>>  
>> -	if (skb_tailroom(skb) >= padlen + KSZ_INGRESS_TAG_LEN) {
>> +	if (skb_tailroom(skb) >= padlen + len) {
>>  		/* Let dsa_slave_xmit() free skb */
>>  		if (__skb_put_padto(skb, skb->len + padlen, false))
>>  			return NULL;
> 
> Hi Marek

Hi,

> This can return NULL.
> 
>> +static struct sk_buff *ksz9477_xmit(struct sk_buff *skb,
>> +				    struct net_device *dev)
>> +{
>> +	struct dsa_port *dp = dsa_slave_to_port(dev);
>> +	struct sk_buff *nskb;
>> +	u16 *tag;
>> +	u8 *addr;
>> +
>> +	nskb = ksz_common_xmit(skb, dev, KSZ9477_INGRESS_TAG_LEN);
> 
> So here you need to check for NULL

What do we do if the xmit returns NULL ?

-- 
Best regards,
Marek Vasut