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Subject: Re: [PATCH] arp: Remove the arp_hh_ops structure
To:     Yejune Deng <yejune.deng@gmail.com>, davem@davemloft.net,
        yoshfuji@linux-ipv6.org, dsahern@kernel.org, kuba@kernel.org
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20210220043203.11754-1-yejune.deng@gmail.com>
From:   David Ahern <dsahern@gmail.com>
Message-ID: <3b69191b-9bd5-9050-9126-17b4905a67e9@gmail.com>
Date:   Sat, 20 Feb 2021 18:54:08 -0700
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On 2/19/21 9:32 PM, Yejune Deng wrote:
>  static const struct neigh_ops arp_direct_ops = {
>  	.family =		AF_INET,
>  	.output =		neigh_direct_output,
> @@ -277,15 +269,10 @@ static int arp_constructor(struct neighbour *neigh)
>  			memcpy(neigh->ha, dev->broadcast, dev->addr_len);
>  		}
>  
> -		if (dev->header_ops->cache)
> -			neigh->ops = &arp_hh_ops;
> -		else
> -			neigh->ops = &arp_generic_ops;

How did you test this?

you took out the neigh->ops assignment, so all of the neigh->ops in
net/core/neighbour.c are going to cause a NULL dereference.


> -
> -		if (neigh->nud_state & NUD_VALID)
> -			neigh->output = neigh->ops->connected_output;
> +		if (!dev->header_ops->cache && (neigh->nud_state & NUD_VALID))
> +			neigh->output = arp_generic_ops.connected_output;
>  		else
> -			neigh->output = neigh->ops->output;
> +			neigh->output = arp_generic_ops.output;
>  	}
>  	return 0;
>  }
>