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Subject: Re: [PATCH] selftests/bpf: fix array_size.cocci warning
From:   Daniel Borkmann <daniel@iogearbox.net>
To:     Guo Zhengkui <guozhengkui@vivo.com>, Shuah Khan <shuah@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>,
        Dave Marchevsky <davemarchevsky@fb.com>,
        Yucong Sun <sunyucong@gmail.com>,
        Christy Lee <christylee@fb.com>,
        Delyan Kratunov <delyank@fb.com>,
        =?UTF-8?Q?Toke_H=c3=b8iland-J=c3=b8rgense?= =?UTF-8?Q?n?= 
        <toke@redhat.com>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>,
        "open list:BPF (Safe dynamic programs and tools)" 
        <netdev@vger.kernel.org>,
        "open list:BPF (Safe dynamic programs and tools)" 
        <bpf@vger.kernel.org>, open list <linux-kernel@vger.kernel.org>
Cc:     zhengkui_guo@outlook.com
References: <20220308091813.28574-1-guozhengkui@vivo.com>
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Date:   Tue, 8 Mar 2022 16:00:22 +0100
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On 3/8/22 3:59 PM, Daniel Borkmann wrote:
> 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.

Also, CI failed with your patch:

https://github.com/kernel-patches/bpf/runs/5462211251?check_suite_focus=true

   In file included from progs/test_rdonly_maps.c:6:
   In file included from /usr/include/linux/kernel.h:5:
   /usr/include/linux/sysinfo.h:9:2: error: unknown type name '__kernel_long_t'
           __kernel_long_t uptime;         /* Seconds since boot */
           ^
   /usr/include/linux/sysinfo.h:10:2: error: unknown type name '__kernel_ulong_t'
           __kernel_ulong_t loads[3];      /* 1, 5, and 15 minute load averages */
           ^
   /usr/include/linux/sysinfo.h:11:2: error: unknown type name '__kernel_ulong_t'
           __kernel_ulong_t totalram;      /* Total usable main memory size */
           ^
   /usr/include/linux/sysinfo.h:12:2: error: unknown type name '__kernel_ulong_t'
           __kernel_ulong_t freeram;       /* Available memory size */
           ^
   /usr/include/linux/sysinfo.h:13:2: error: unknown type name '__kernel_ulong_t'
           __kernel_ulong_t sharedram;     /* Amount of shared memory */
           ^
   /usr/include/linux/sysinfo.h:14:2: error: unknown type name '__kernel_ulong_t'
           __kernel_ulong_t bufferram;     /* Memory used by buffers */
           ^
   /usr/include/linux/sysinfo.h:15:2: error: unknown type name '__kernel_ulong_t'
           __kernel_ulong_t totalswap;     /* Total swap space size */
           ^
   /usr/include/linux/sysinfo.h:16:2: error: unknown type name '__kernel_ulong_t'
           __kernel_ulong_t freeswap;      /* swap space still available */
           ^
   /usr/include/linux/sysinfo.h:19:2: error: unknown type name '__kernel_ulong_t'
           __kernel_ulong_t totalhigh;     /* Total high memory size */
           ^
   /usr/include/linux/sysinfo.h:20:2: error: unknown type name '__kernel_ulong_t'
           __kernel_ulong_t freehigh;      /* Available high memory size */
           ^
   /usr/include/linux/sysinfo.h:22:22: error: use of undeclared identifier '__kernel_ulong_t'
           char _f[20-2*sizeof(__kernel_ulong_t)-sizeof(__u32)];   /* Padding: libc5 uses this.. */
                               ^
   progs/test_rdonly_maps.c:68:10: error: implicit declaration of function 'ARRAY_SIZE' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
           int i = ARRAY_SIZE(rdonly_values.a);
                   ^
   12 errors generated.
   make: *** [Makefile:488: /tmp/runner/work/bpf/bpf/tools/testing/selftests/bpf/test_rdonly_maps.o] Error 1
   make: *** Waiting for unfinished jobs....
   Error: Process completed with exit code 2.