linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "wanghai (M)" <wanghai38@huawei.com>
To: Jesper Dangaard Brouer <jbrouer@redhat.com>,
	<davem@davemloft.net>, <kuba@kernel.org>, <ast@kernel.org>,
	<daniel@iogearbox.net>, <hawk@kernel.org>,
	<john.fastabend@gmail.com>, <andrii@kernel.org>, <kafai@fb.com>,
	<songliubraving@fb.com>, <yhs@fb.com>, <kpsingh@kernel.org>
Cc: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH bpf] samples/bpf: Fix the error return code of xdp_redirect's main()
Date: Mon, 5 Jul 2021 15:45:07 +0800	[thread overview]
Message-ID: <6f35ad34-1334-bdae-da7f-a20f1af34ea5@huawei.com> (raw)
In-Reply-To: <94aad4ed-8384-1841-88ec-6c7e39d63148@redhat.com>


在 2021/7/2 18:29, Jesper Dangaard Brouer 写道:
>
> On 16/06/2021 06.25, Wang Hai wrote:
>> Fix to return a negative error code from the error handling
>> case instead of 0, as done elsewhere in this function.
>
> The main() function in C should never return a negative value on Unix 
> POSIX systems.
>
>
> There is a good explaination in exit(3p): `man 3p exit`
>
>    The  value  of  status may be 0, EXIT_SUCCESS, EXIT_FAILURE, or any 
> other value, though only the least significant 8 bits (that is, status 
> & 0377) shall be available to a waiting parent process.
>
> Thus, negative values are often seen as 255 in the $? program exit 
> status variable $?.
>
>
> Also explained in exit(3):
>
>     The C standard specifies two constants, EXIT_SUCCESS=0 and 
> EXIT_FAILURE=1.
>
> I see the 'samples/bpf/xdp_redirect_user.c' in most places just use 0 
> or 1.
>
Got it, thanks for the explanation, I will fix it to return 1, just like 
the other error paths in samples/bpf/xdp_redirect_user.c
>
>> If bpf_map_update_elem() failed, main() should return a negative error.
>>
>> Fixes: 832622e6bd18 ("xdp: sample program for new bpf_redirect helper")
>> Signed-off-by: Wang Hai <wanghai38@huawei.com>
>> ---
>>   samples/bpf/xdp_redirect_user.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/samples/bpf/xdp_redirect_user.c 
>> b/samples/bpf/xdp_redirect_user.c
>> index 41d705c3a1f7..c903f1ccc15e 100644
>> --- a/samples/bpf/xdp_redirect_user.c
>> +++ b/samples/bpf/xdp_redirect_user.c
>> @@ -213,5 +213,5 @@ int main(int argc, char **argv)
>>       poll_stats(2, ifindex_out);
>>     out:
>> -    return 0;
>> +    return ret;
>>   }
>
>
> (Sorry, I didn't complain it time as I see this patch is already applied)
>
> .
>

      reply	other threads:[~2021-07-05  7:45 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-16  4:25 [PATCH bpf] samples/bpf: Fix the error return code of xdp_redirect's main() Wang Hai
2021-06-18 18:20 ` patchwork-bot+netdevbpf
2021-07-02 10:29 ` Jesper Dangaard Brouer
2021-07-05  7:45   ` wanghai (M) [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=6f35ad34-1334-bdae-da7f-a20f1af34ea5@huawei.com \
    --to=wanghai38@huawei.com \
    --cc=andrii@kernel.org \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=davem@davemloft.net \
    --cc=hawk@kernel.org \
    --cc=jbrouer@redhat.com \
    --cc=john.fastabend@gmail.com \
    --cc=kafai@fb.com \
    --cc=kpsingh@kernel.org \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=songliubraving@fb.com \
    --cc=yhs@fb.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).