bpf.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Daniel Borkmann <daniel@iogearbox.net>
To: Jianlin Lv <Jianlin.Lv@arm.com>, bpf@vger.kernel.org
Cc: davem@davemloft.net, kuba@kernel.org, ast@kernel.org, yhs@fb.com,
	Song.Zhu@arm.com, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org
Subject: Re: [PATCH bpf-next] bpf: fix compilation warning of selftests
Date: Fri, 31 Jul 2020 17:00:05 +0200	[thread overview]
Message-ID: <6f852dcb-abfc-78f8-69b8-3a5b83606793@iogearbox.net> (raw)
In-Reply-To: <20200731061600.18344-1-Jianlin.Lv@arm.com>

On 7/31/20 8:16 AM, Jianlin Lv wrote:
> Clang compiler version: 12.0.0
> The following warning appears during the selftests/bpf compilation:
> 
> prog_tests/send_signal.c:51:3: warning: ignoring return value of ‘write’,
> declared with attribute warn_unused_result [-Wunused-result]
>     51 |   write(pipe_c2p[1], buf, 1);
>        |   ^~~~~~~~~~~~~~~~~~~~~~~~~~
> prog_tests/send_signal.c:54:3: warning: ignoring return value of ‘read’,
> declared with attribute warn_unused_result [-Wunused-result]
>     54 |   read(pipe_p2c[0], buf, 1);
>        |   ^~~~~~~~~~~~~~~~~~~~~~~~~
> ......
> 
> prog_tests/stacktrace_build_id_nmi.c:13:2: warning: ignoring return value
> of ‘fscanf’,declared with attribute warn_unused_result [-Wunused-resul]
>     13 |  fscanf(f, "%llu", &sample_freq);
>        |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> test_tcpnotify_user.c:133:2: warning:ignoring return value of ‘system’,
> declared with attribute warn_unused_result [-Wunused-result]
>    133 |  system(test_script);
>        |  ^~~~~~~~~~~~~~~~~~~
> test_tcpnotify_user.c:138:2: warning:ignoring return value of ‘system’,
> declared with attribute warn_unused_result [-Wunused-result]
>    138 |  system(test_script);
>        |  ^~~~~~~~~~~~~~~~~~~
> test_tcpnotify_user.c:143:2: warning:ignoring return value of ‘system’,
> declared with attribute warn_unused_result [-Wunused-result]
>    143 |  system(test_script);
>        |  ^~~~~~~~~~~~~~~~~~~
> 
> Add code that fix compilation warning about ignoring return value and
> handles any errors; Check return value of library`s API make the code
> more secure.
> 
> Signed-off-by: Jianlin Lv <Jianlin.Lv@arm.com>

Looks good overall, there is one small bug that slipped in, see below:

[...]
> diff --git a/tools/testing/selftests/bpf/test_tcpnotify_user.c b/tools/testing/selftests/bpf/test_tcpnotify_user.c
> index f9765ddf0761..869e28c92d73 100644
> --- a/tools/testing/selftests/bpf/test_tcpnotify_user.c
> +++ b/tools/testing/selftests/bpf/test_tcpnotify_user.c
> @@ -130,17 +130,26 @@ int main(int argc, char **argv)
>   	sprintf(test_script,
>   		"iptables -A INPUT -p tcp --dport %d -j DROP",
>   		TESTPORT);
> -	system(test_script);
> +	if (system(test_script)) {
> +		printf("FAILED: execute command: %s\n", test_script);
> +		goto err;
> +	}
>   
>   	sprintf(test_script,
>   		"nc 127.0.0.1 %d < /etc/passwd > /dev/null 2>&1 ",
>   		TESTPORT);
> -	system(test_script);
> +	if (system(test_script)) {
> +		printf("FAILED: execute command: %s\n", test_script);
> +		goto err;
> +	}

Did you try to run this test case? With the patch here it will fail:

   # ./test_tcpnotify_user
   FAILED: execute command: nc 127.0.0.1 12877 < /etc/passwd > /dev/null 2>&1

This is because nc returns 1 as exit code and for the test it is actually expected
to fail given the iptables rule we installed for TESTPORT right above and remove
again below.

Please adapt this and send a v2, thanks!

>   	sprintf(test_script,
>   		"iptables -D INPUT -p tcp --dport %d -j DROP",
>   		TESTPORT);
> -	system(test_script);
> +	if (system(test_script)) {
> +		printf("FAILED: execute command: %s\n", test_script);
> +		goto err;
> +	}
>   
>   	rv = bpf_map_lookup_elem(bpf_map__fd(global_map), &key, &g);
>   	if (rv != 0) {
> 


  reply	other threads:[~2020-07-31 15:00 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-31  6:16 [PATCH bpf-next] bpf: fix compilation warning of selftests Jianlin Lv
2020-07-31 15:00 ` Daniel Borkmann [this message]
2020-07-31 17:39 ` Andrii Nakryiko
2020-08-06 10:42 ` [PATCH bpf-next v2] " Jianlin Lv
2020-08-07  0:05   ` Alexei Starovoitov
2020-08-07 17:20 ` [PATCH bpf-next] bpf: fix segmentation fault of test_progs Jianlin Lv
2020-08-07 20:13   ` Andrii Nakryiko
2020-08-10 15:39   ` [PATCH bpf-next v2] " Jianlin Lv
2020-08-11  0:23     ` Andrii Nakryiko
2020-08-11 13:19     ` Daniel Borkmann

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=6f852dcb-abfc-78f8-69b8-3a5b83606793@iogearbox.net \
    --to=daniel@iogearbox.net \
    --cc=Jianlin.Lv@arm.com \
    --cc=Song.Zhu@arm.com \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=davem@davemloft.net \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --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).