Re: [PATCH] selftests/bpf: fix array_size.cocci warning

[Daniel Borkmann <daniel@iogearbox.net>]

On 3/8/22 10:17 AM, Guo Zhengkui wrote:
> Fix the array_size.cocci warning in tools/testing/selftests/bpf/
> 
> Use `ARRAY_SIZE(arr)` instead of forms like `sizeof(arr)/sizeof(arr[0])`.
> 
> syscall.c and test_rdonly_maps.c don't contain header files which
> implement ARRAY_SIZE() macro. So I add `#include <linux/kernel.h>`,
> in which ARRAY_SIZE(arr) not only calculates the size of `arr`, but also
> checks that `arr` is really an array (using __must_be_array(arr)).
> 
> Signed-off-by: Guo Zhengkui <guozhengkui@vivo.com>
[...]
> diff --git a/tools/testing/selftests/bpf/progs/syscall.c b/tools/testing/selftests/bpf/progs/syscall.c
> index e550f728962d..85c6e7849463 100644
> --- a/tools/testing/selftests/bpf/progs/syscall.c
> +++ b/tools/testing/selftests/bpf/progs/syscall.c
> @@ -6,6 +6,7 @@
>   #include <bpf/bpf_tracing.h>
>   #include <../../../tools/include/linux/filter.h>
>   #include <linux/btf.h>
> +#include <linux/kernel.h>
>   
>   char _license[] SEC("license") = "GPL";
>   
> @@ -82,7 +83,7 @@ int bpf_prog(struct args *ctx)
>   	static __u64 value = 34;
>   	static union bpf_attr prog_load_attr = {
>   		.prog_type = BPF_PROG_TYPE_XDP,
> -		.insn_cnt = sizeof(insns) / sizeof(insns[0]),
> +		.insn_cnt = ARRAY_SIZE(insns),
>   	};
>   	int ret;
>   
> diff --git a/tools/testing/selftests/bpf/progs/test_rdonly_maps.c b/tools/testing/selftests/bpf/progs/test_rdonly_maps.c
> index fc8e8a34a3db..ca75aac745a4 100644
> --- a/tools/testing/selftests/bpf/progs/test_rdonly_maps.c
> +++ b/tools/testing/selftests/bpf/progs/test_rdonly_maps.c
> @@ -3,6 +3,7 @@
>   
>   #include <linux/ptrace.h>
>   #include <linux/bpf.h>
> +#include <linux/kernel.h>
>   #include <bpf/bpf_helpers.h>
>   
>   const struct {
> @@ -64,7 +65,7 @@ int full_loop(struct pt_regs *ctx)
>   {
>   	/* prevent compiler to optimize everything out */
>   	unsigned * volatile p = (void *)&rdonly_values.a;
> -	int i = sizeof(rdonly_values.a) / sizeof(rdonly_values.a[0]);
> +	int i = ARRAY_SIZE(rdonly_values.a);
>   	unsigned iters = 0, sum = 0;
>   

There's bpf_util.h with ARRAY_SIZE definition which is used in selftests, pls change to
reuse that one.

Thanks,
Daniel