netdev - Re: [PATCH] bpf: verifier: avoid fall-through warnings

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Message-ID: <4acbc6b9-e2aa-02d3-0e99-f641b67a3da3@embeddedor.com>
Date:   Tue, 11 Jun 2019 12:27:29 -0500
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Lawrence Brakmo <brakmo@...com>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH] bpf: verifier: avoid fall-through warnings



On 6/11/19 12:22 PM, Andrii Nakryiko wrote:
> On Tue, Jun 11, 2019 at 7:05 AM Gustavo A. R. Silva
> <gustavo@...eddedor.com> wrote:
>>
>> In preparation to enabling -Wimplicit-fallthrough, this patch silences
>> the following warning:
> 
> Your patch doesn't apply cleanly to neither bpf nor bpf-next tree.
> Could you please rebase and re-submit? Please also include which tree
> (probably bpf-next) you are designating this patch to in subject
> prefix.
> 

This patch applies cleanly to linux-next (tag next-20190611).

--
Gustavo

>>
>> kernel/bpf/verifier.c: In function ‘check_return_code’:
>> kernel/bpf/verifier.c:5509:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
>>    if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG ||
>>       ^
>> kernel/bpf/verifier.c:5512:2: note: here
>>   case BPF_PROG_TYPE_CGROUP_SKB:
>>   ^~~~
>>
>> Warning level 3 was used: -Wimplicit-fallthrough=3
>>
>> Notice that it's much clearer to explicitly add breaks in each case
>> (that actually contains some code), rather than letting the code to
>> fall through.
>>
>> This patch is part of the ongoing efforts to enable
>> -Wimplicit-fallthrough.
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
>> ---
>>  kernel/bpf/verifier.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
>> index 1e9d10b32984..e9fc28991548 100644
>> --- a/kernel/bpf/verifier.c
>> +++ b/kernel/bpf/verifier.c
>> @@ -5509,11 +5509,13 @@ static int check_return_code(struct bpf_verifier_env *env)
>>                 if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG ||
>>                     env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG)
>>                         range = tnum_range(1, 1);
>> +               break;
>>         case BPF_PROG_TYPE_CGROUP_SKB:
>>                 if (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS) {
>>                         range = tnum_range(0, 3);
>>                         enforce_attach_type_range = tnum_range(2, 3);
>>                 }
>> +               break;
>>         case BPF_PROG_TYPE_CGROUP_SOCK:
>>         case BPF_PROG_TYPE_SOCK_OPS:
>>         case BPF_PROG_TYPE_CGROUP_DEVICE:
>> --
>> 2.21.0
>>