Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <YCwewjRBJIBm0sew@mwanda>
In-Reply-To: <YCwewjRBJIBm0sew@mwanda>
From:   KP Singh <kpsingh@kernel.org>
Date:   Tue, 16 Feb 2021 22:10:10 +0100
Message-ID: <CACYkzJ55Ze+aA+qKA8bf=iqNY01H=MuDCKVmn44fLVW1670RxA@mail.gmail.com>
Subject: Re: [PATCH] bpf: fix a warning message in mark_ptr_not_null_reg()
To:     Dan Carpenter <dan.carpenter@oracle.com>
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Dmitrii Banshchikov <me@ubique.spb.ru>,
        Daniel Borkmann <daniel@iogearbox.net>,
        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>,
        bpf <bpf@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        kernel-janitors@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, Feb 16, 2021 at 8:37 PM Dan Carpenter <dan.carpenter@oracle.com> wrote:
>
> The WARN_ON() argument is a condition, and it generates a stack trace
> but it doesn't print the warning.
>
> Fixes: 4ddb74165ae5 ("bpf: Extract nullable reg type conversion into a helper function")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>  kernel/bpf/verifier.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 056df6be3e30..bd4d1dfca73c 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -1120,7 +1120,7 @@ static void mark_ptr_not_null_reg(struct bpf_reg_state *reg)
>                 reg->type = PTR_TO_RDWR_BUF;
>                 break;
>         default:
> -               WARN_ON("unknown nullable register type");
> +               WARN(1, "unknown nullable register type");

Should we use WARN_ONCE here? Also, I think the fix should be targeted
for bpf-next as
the patch that introduced this hasn't made it to bpf yet.

[...]