netdev - Re: [PATCH bpf-next] bpf: cgroup: Fix build error without CONFIG

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Date:   Wed, 3 Jul 2019 16:01:12 +0800
From:   Yuehaibing <yuehaibing@...wei.com>
To:     Stanislav Fomichev <sdf@...ichev.me>
CC:     <ast@...nel.org>, <daniel@...earbox.net>, <kafai@...com>,
        <songliubraving@...com>, <yhs@...com>, <sdf@...gle.com>,
        <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
        <bpf@...r.kernel.org>
Subject: Re: [PATCH bpf-next] bpf: cgroup: Fix build error without CONFIG_NET

On 2019/7/2 23:53, Stanislav Fomichev wrote:
> On 07/02, YueHaibing wrote:
>> If CONFIG_NET is not set, gcc building fails:
>>
>> kernel/bpf/cgroup.o: In function `cg_sockopt_func_proto':
>> cgroup.c:(.text+0x237e): undefined reference to `bpf_sk_storage_get_proto'
>> cgroup.c:(.text+0x2394): undefined reference to `bpf_sk_storage_delete_proto'
>> kernel/bpf/cgroup.o: In function `__cgroup_bpf_run_filter_getsockopt':
>> (.text+0x2a1f): undefined reference to `lock_sock_nested'
>> (.text+0x2ca2): undefined reference to `release_sock'
>> kernel/bpf/cgroup.o: In function `__cgroup_bpf_run_filter_setsockopt':
>> (.text+0x3006): undefined reference to `lock_sock_nested'
>> (.text+0x32bb): undefined reference to `release_sock'
>>
>> Add CONFIG_NET dependency to fix this.
> Can you share the config? Do I understand correctly that you have
> CONFIG_NET=n and CONFIG_BPF=y? What parts of BPF do you expect to
> work in this case?

Yes, I get this error while doing randconfig building,
it set CONFIG_CGROUP_BPF=y and CONFIG_NET=n

the config file attached.

> 
> Less invasive fix would be something along the lines:
> 
> diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
> index 76fa0076f20d..0a00eaca6fae 100644
> --- a/kernel/bpf/cgroup.c
> +++ b/kernel/bpf/cgroup.c
> @@ -939,6 +939,7 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head,
>  }
>  EXPORT_SYMBOL(__cgroup_bpf_run_filter_sysctl);
>  
> +#ifdef CONFIG_NET
>  static bool __cgroup_bpf_prog_array_is_empty(struct cgroup *cgrp,
>  					     enum bpf_attach_type attach_type)
>  {
> @@ -1120,6 +1121,7 @@ int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
>  	return ret;
>  }
>  EXPORT_SYMBOL(__cgroup_bpf_run_filter_getsockopt);
> +#endif
>  
>  static ssize_t sysctl_cpy_dir(const struct ctl_dir *dir, char **bufp,
>  			      size_t *lenp)
> @@ -1386,10 +1388,12 @@ static const struct bpf_func_proto *
>  cg_sockopt_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
>  {
>  	switch (func_id) {
> +#ifdef CONFIG_NET
>  	case BPF_FUNC_sk_storage_get:
>  		return &bpf_sk_storage_get_proto;
>  	case BPF_FUNC_sk_storage_delete:
>  		return &bpf_sk_storage_delete_proto;
> +#endif
>  #ifdef CONFIG_INET
>  	case BPF_FUNC_tcp_sock:
>  		return &bpf_tcp_sock_proto;
> 
>> Reported-by: Hulk Robot <hulkci@...wei.com>
>> Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks")
>> Signed-off-by: YueHaibing <yuehaibing@...wei.com>
>> ---
>>  init/Kconfig | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/init/Kconfig b/init/Kconfig
>> index e2e51b5..341cf2a 100644
>> --- a/init/Kconfig
>> +++ b/init/Kconfig
>> @@ -998,6 +998,7 @@ config CGROUP_PERF
>>  config CGROUP_BPF
>>  	bool "Support for eBPF programs attached to cgroups"
>>  	depends on BPF_SYSCALL
>> +	depends on NET
>>  	select SOCK_CGROUP_DATA
>>  	help
>>  	  Allow attaching eBPF programs to a cgroup using the bpf(2)
>> -- 
>> 2.7.4
>>
>>
> 
> .
> 

View attachment "randconfig.txt" of type "text/plain" (92974 bytes)