答复: [PATCH bpf-next] samples/bpf: detach xdp prog when program exits unexpectedly in xdp_rxq_info_user

[shaozhengchao <shaozhengchao@huawei.com>]

Thank you for your reply.

I will fix the compilation warning firstly, and then convert this sample to skeleton. Thank you very much.

-----邮件原件-----
发件人: Andrii Nakryiko [mailto:andrii.nakryiko@gmail.com] 
发送时间: 2022年4月26日 12:35
收件人: shaozhengchao <shaozhengchao@huawei.com>
抄送: bpf <bpf@vger.kernel.org>; Networking <netdev@vger.kernel.org>; open list <linux-kernel@vger.kernel.org>; Alexei Starovoitov <ast@kernel.org>; Daniel Borkmann <daniel@iogearbox.net>; David S. Miller <davem@davemloft.net>; Jakub Kicinski <kuba@kernel.org>; Jesper Dangaard Brouer <hawk@kernel.org>; john fastabend <john.fastabend@gmail.com>; Andrii Nakryiko <andrii@kernel.org>; Martin Lau <kafai@fb.com>; Song Liu <songliubraving@fb.com>; Yonghong Song <yhs@fb.com>; KP Singh <kpsingh@kernel.org>; weiyongjun (A) <weiyongjun1@huawei.com>; yuehaibing <yuehaibing@huawei.com>
主题: Re: [PATCH bpf-next] samples/bpf: detach xdp prog when program exits unexpectedly in xdp_rxq_info_user

On Thu, Apr 21, 2022 at 5:07 AM Zhengchao Shao <shaozhengchao@huawei.com> wrote:
>
> When xdp_rxq_info_user program exits unexpectedly, it doesn't detach 
> xdp prog of device, and other xdp prog can't be attached to the 
> device. So call init_exit() to detach xdp prog when program exits unexpectedly.
>
> Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
> ---
>  samples/bpf/xdp_rxq_info_user.c | 21 +++++++++++++++------
>  1 file changed, 15 insertions(+), 6 deletions(-)
>

you are introducing a new compilation warning, please fix it


/data/users/andriin/linux/samples/bpf/xdp_rxq_info_user.c: In function
‘options2str’:
/data/users/andriin/linux/samples/bpf/xdp_rxq_info_user.c:153:1:
warning: control reaches end of non-void function [-Wreturn-type]
  153 | }
      | ^

It also would be good to instead use bpf_link-based XDP attachment that would be auto-detached automatically on process crash
(bpf_link_create() FTW). Please consider also converting this sample to skeleton (and then bpf_program__attach_xdp() as high-level alternative to bpf_link_create()).

> diff --git a/samples/bpf/xdp_rxq_info_user.c 
> b/samples/bpf/xdp_rxq_info_user.c index f2d90cba5164..6378007e085a 
> 100644
> --- a/samples/bpf/xdp_rxq_info_user.c
> +++ b/samples/bpf/xdp_rxq_info_user.c
> @@ -18,7 +18,7 @@ static const char *__doc__ = " XDP RX-queue info extract example\n\n"
>  #include <getopt.h>
>  #include <net/if.h>
>  #include <time.h>

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