On 7/21/20 3:07 AM, Jakub Sitnicki wrote:
> When CONFIG_NET is set but CONFIG_INET isn't, build fails with:
> 
>   ld: kernel/bpf/net_namespace.o: in function `netns_bpf_attach_type_unneed':
>   kernel/bpf/net_namespace.c:32: undefined reference to 
> `bpf_sk_lookup_enabled'
>   ld: kernel/bpf/net_namespace.o: in function `netns_bpf_attach_type_need':
>   kernel/bpf/net_namespace.c:43: undefined reference to 
> `bpf_sk_lookup_enabled'
> 
> This is because without CONFIG_INET bpf_sk_lookup_enabled symbol is not
> available. Wrap references to bpf_sk_lookup_enabled with preprocessor
> conditionals.
> 
> Fixes: 1559b4aa1db4 ("inet: Run SK_LOOKUP BPF program on socket lookup")
> Reported-by: Randy Dunlap <rdun...@infradead.org>
> Reported-by: Stephen Rothwell <s...@canb.auug.org.au>
> Signed-off-by: Jakub Sitnicki <ja...@cloudflare.com>

Acked-by: Randy Dunlap <rdun...@infradead.org> # build-tested

Thanks.

> ---
>  kernel/bpf/net_namespace.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/kernel/bpf/net_namespace.c b/kernel/bpf/net_namespace.c
> index 4e1bcaa2c3cb..71405edd667c 100644
> --- a/kernel/bpf/net_namespace.c
> +++ b/kernel/bpf/net_namespace.c
> @@ -28,9 +28,11 @@ DEFINE_MUTEX(netns_bpf_mutex);
>  static void netns_bpf_attach_type_unneed(enum netns_bpf_attach_type type)
>  {
>       switch (type) {
> +#ifdef CONFIG_INET
>       case NETNS_BPF_SK_LOOKUP:
>               static_branch_dec(&bpf_sk_lookup_enabled);
>               break;
> +#endif
>       default:
>               break;
>       }
> @@ -39,9 +41,11 @@ static void netns_bpf_attach_type_unneed(enum 
> netns_bpf_attach_type type)
>  static void netns_bpf_attach_type_need(enum netns_bpf_attach_type type)
>  {
>       switch (type) {
> +#ifdef CONFIG_INET
>       case NETNS_BPF_SK_LOOKUP:
>               static_branch_inc(&bpf_sk_lookup_enabled);
>               break;
> +#endif
>       default:
>               break;
>       }
> 


-- 
~Randy

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