linux-kernel - Re: [PATCH -next] bpf: Make some functions static

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Message-ID: <cf3411eb-8129-ecc4-4975-a995d114cf7e@fb.com>
Date:   Mon, 20 Jul 2020 09:18:13 -0700
From:   Yonghong Song <yhs@...com>
To:     Wang Hai <wanghai38@...wei.com>, <davem@...emloft.net>,
        <kuba@...nel.org>, <ast@...nel.org>, <daniel@...earbox.net>,
        <kafai@...com>, <songliubraving@...com>, <andriin@...com>,
        <john.fastabend@...il.com>, <kpsingh@...omium.org>
CC:     <netdev@...r.kernel.org>, <bpf@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -next] bpf: Make some functions static



On 7/18/20 4:51 AM, Wang Hai wrote:
> Fix sparse build warning:
> 
> net/bpf/test_run.c:120:14: warning:
>   symbol 'bpf_fentry_test1' was not declared. Should it be static?
> net/bpf/test_run.c:125:14: warning:
>   symbol 'bpf_fentry_test2' was not declared. Should it be static?
> net/bpf/test_run.c:130:14: warning:
>   symbol 'bpf_fentry_test3' was not declared. Should it be static?
> net/bpf/test_run.c:135:14: warning:
>   symbol 'bpf_fentry_test4' was not declared. Should it be static?
> net/bpf/test_run.c:140:14: warning:
>   symbol 'bpf_fentry_test5' was not declared. Should it be static?
> net/bpf/test_run.c:145:14: warning:
>   symbol 'bpf_fentry_test6' was not declared. Should it be static?
> net/bpf/test_run.c:154:14: warning:
>   symbol 'bpf_fentry_test7' was not declared. Should it be static?
> net/bpf/test_run.c:159:14: warning:
>   symbol 'bpf_fentry_test8' was not declared. Should it be static?
> net/bpf/test_run.c:164:14: warning:
>   symbol 'bpf_modify_return_test' was not declared. Should it be static?
> 
> Reported-by: Hulk Robot <hulkci@...wei.com>
> Signed-off-by: Wang Hai <wanghai38@...wei.com>

Please see commit:

commit e9ff9d52540a53ce8c9eff5bf8b66467fe81eb2b
Author: Jean-Philippe Menil <jpmenil@...il.com>
Date:   Fri Mar 27 21:47:13 2020 +0100

     bpf: Fix build warning regarding missing prototypes

     Fix build warnings when building net/bpf/test_run.o with W=1 due
     to missing prototype for bpf_fentry_test{1..6}.

     Instead of declaring prototypes, turn off warnings with
     __diag_{push,ignore,pop} as pointed out by Alexei.

You probably use an old compiler (gcc < 8) which is why
the warning is emitted.

> ---
>   net/bpf/test_run.c | 18 +++++++++---------
>   1 file changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> index b03c469cd01f..0d78bd9b6c9d 100644
> --- a/net/bpf/test_run.c
> +++ b/net/bpf/test_run.c
> @@ -117,32 +117,32 @@ static int bpf_test_finish(const union bpf_attr *kattr,
>   __diag_push();
>   __diag_ignore(GCC, 8, "-Wmissing-prototypes",
>   	      "Global functions as their definitions will be in vmlinux BTF");
> -int noinline bpf_fentry_test1(int a)
> +static noinline int bpf_fentry_test1(int a)
>   {
>   	return a + 1;
>   }
>   
> -int noinline bpf_fentry_test2(int a, u64 b)
> +static noinline int bpf_fentry_test2(int a, u64 b)
>   {
>   	return a + b;
>   }
>   
> -int noinline bpf_fentry_test3(char a, int b, u64 c)
> +static noinline int bpf_fentry_test3(char a, int b, u64 c)
>   {
>   	return a + b + c;
>   }
>   
[...]