netdev - Re: [PATCH -next] btf: fix return value check in btf_vmlinux

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Date:   Thu, 15 Aug 2019 10:06:07 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Wei Yongjun <weiyongjun1@...wei.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>,
        Andrii Nakryiko <andriin@...com>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH -next] btf: fix return value check in btf_vmlinux_init()

On Thu, Aug 15, 2019 at 7:21 AM Wei Yongjun <weiyongjun1@...wei.com> wrote:
>
> In case of error, the function kobject_create_and_add() returns NULL
> pointer not ERR_PTR(). The IS_ERR() test in the return value check
> should be replaced with NULL test.
>
> Fixes: 341dfcf8d78e ("btf: expose BTF info through sysfs")
> Signed-off-by: Wei Yongjun <weiyongjun1@...wei.com>
> ---


Argh... Thanks for the fix! Fix the comment below addressed:

Acked-by: Andrii Nakryiko <andriin@...com>

>  kernel/bpf/sysfs_btf.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/bpf/sysfs_btf.c b/kernel/bpf/sysfs_btf.c
> index 4659349fc795..be5557deb958 100644
> --- a/kernel/bpf/sysfs_btf.c
> +++ b/kernel/bpf/sysfs_btf.c
> @@ -30,16 +30,13 @@ static struct kobject *btf_kobj;
>
>  static int __init btf_vmlinux_init(void)
>  {
> -       int err;
> -
>         if (!_binary__btf_vmlinux_bin_start)
>                 return 0;
>
>         btf_kobj = kobject_create_and_add("btf", kernel_kobj);
> -       if (IS_ERR(btf_kobj)) {
> -               err = PTR_ERR(btf_kobj);
> +       if (!btf_kobj) {
>                 btf_kobj = NULL;

This is now not necessary, please drop (and don't forget to remove {}
for this single-line if afterwards).

> -               return err;
> +               return -ENOMEM;
>         }
>
>         bin_attr_btf_vmlinux.size = _binary__btf_vmlinux_bin_end -
>
>
>