Re: [linux-next:master 5404/5655] net/core/filter.c:12578:18: warning: unused variable 'nskb'

On 7/10/26 7:37 PM, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   bee763d5f341b99cf472afeb508d4988f62a6ca1
> commit: f3603df9aebb2a2fe2f745bd71ca38aeca60e6e7 [5404/5655] bpf: Add bpf_icmp_send kfunc
> config: i386-buildonly-randconfig-001-20260710 (https://download.01.org/0day-ci/archive/20260711/[email protected]/config)
> compiler: clang version 22.1.3 (https://github.com/llvm/llvm-project e9846648fd6183ee6d8cbdb4502213fcf902a211)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260711/[email protected]/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <[email protected]>
> | Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
> 
> All warnings (new ones prefixed by >>):
> 
>>> net/core/filter.c:12578:18: warning: unused variable 'nskb' [-Wunused-variable]
>      12578 |         struct sk_buff *nskb;
>            |                         ^~~~
>     1 warning generated.

oh well, pls send a fix, Mahe.

> 
> vim +/nskb +12578 net/core/filter.c
> 
>   12553	
>   12554	/**
>   12555	 * bpf_icmp_send - Send an ICMP control message
>   12556	 * @skb_ctx: Packet that triggered the control message
>   12557	 * @type: ICMP type (only ICMP_DEST_UNREACH/ICMPV6_DEST_UNREACH supported)
>   12558	 * @code: ICMP code (0-15 except ICMP_FRAG_NEEDED for IPv4, 0-6 for IPv6)
>   12559	 *
>   12560	 * Sends an ICMP control message in response to the packet. The original packet
>   12561	 * is cloned before sending the ICMP message, so the BPF program can still let
>   12562	 * the packet pass if desired.
>   12563	 *
>   12564	 * Currently only ICMP_DEST_UNREACH (IPv4) and ICMPV6_DEST_UNREACH (IPv6) are
>   12565	 * supported.
>   12566	 *
>   12567	 * Return: 0 on success (send attempt), negative error code on failure:
>   12568	 *         -EBUSY: Recursion detected
>   12569	 *         -EPROTONOSUPPORT: Non-IP protocol
>   12570	 *         -EOPNOTSUPP: Unsupported ICMP type
>   12571	 *         -EINVAL: Invalid code parameter
>   12572	 *         -ENETUNREACH: No usable route/dst for the ICMP reply
>   12573	 *         -ENOMEM: Memory allocation failed
>   12574	 */
>   12575	__bpf_kfunc int bpf_icmp_send(struct __sk_buff *skb_ctx, int type, int code)
>   12576	{
>   12577		struct sk_buff *skb = (struct sk_buff *)skb_ctx;
>   12578		struct sk_buff *nskb;
>   12579		struct sock *sk;
>   12580	
>   12581		sk = skb_to_full_sk(skb);
>   12582		if (sk && sk->sk_kern_sock &&
>   12583		    (sk->sk_protocol == IPPROTO_ICMP || sk->sk_protocol == IPPROTO_ICMPV6))
>   12584			return -EBUSY;
>   12585	
>   12586		if (!skb_valid_dst(skb))
>   12587			return -ENETUNREACH;
>   12588	
>   12589		switch (skb->protocol) {
>   12590	#if IS_ENABLED(CONFIG_INET)
>   12591		case htons(ETH_P_IP): {
>   12592			if (type != ICMP_DEST_UNREACH)
>   12593				return -EOPNOTSUPP;
>   12594			if (code < 0 || code > NR_ICMP_UNREACH ||
>   12595			    code == ICMP_FRAG_NEEDED) /* needs a valid next-hop MTU */
>   12596				return -EINVAL;
>   12597	
>   12598			nskb = skb_clone(skb, GFP_ATOMIC);
>   12599			if (!nskb)
>   12600				return -ENOMEM;
>   12601	
>   12602			memset(IPCB(nskb), 0, sizeof(*IPCB(nskb)));
>   12603			icmp_send(nskb, type, code, 0);
>   12604			consume_skb(nskb);
>   12605			break;
>   12606		}
>   12607	#endif
>   12608	#if IS_ENABLED(CONFIG_IPV6)
>   12609		case htons(ETH_P_IPV6):
>   12610			if (type != ICMPV6_DEST_UNREACH)
>   12611				return -EOPNOTSUPP;
>   12612			if (code < 0 || code > ICMPV6_REJECT_ROUTE)
>   12613				return -EINVAL;
>   12614	
>   12615			nskb = skb_clone(skb, GFP_ATOMIC);
>   12616			if (!nskb)
>   12617				return -ENOMEM;
>   12618	
>   12619			memset(IP6CB(nskb), 0, sizeof(*IP6CB(nskb)));
>   12620			icmpv6_send(nskb, type, code, 0);
>   12621			consume_skb(nskb);
>   12622			break;
>   12623	#endif
>   12624		default:
>   12625			return -EPROTONOSUPPORT;
>   12626		}
>   12627	
>   12628		return 0;
>   12629	}
>   12630	
> 
> --
> 0-DAY CI Kernel Test Service
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