From: Lorenz Bauer <lmb@cloudflare.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Martin KaFai Lau <kafai@fb.com>, Shuah Khan <shuah@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
kernel-team <kernel-team@cloudflare.com>,
"open list:KERNEL SELFTEST FRAMEWORK"
<linux-kselftest@vger.kernel.org>,
Network Development <netdev@vger.kernel.org>,
bpf <bpf@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH bpf-next v2 2/4] selftests: bpf: Add helper to compare socket cookies
Date: Wed, 30 Sep 2020 10:28:33 +0100 [thread overview]
Message-ID: <CACAyw98WzZGcFnnr7ELvbCziz2axJA_7x2mcoQTf2DYWDYJ=KA@mail.gmail.com> (raw)
In-Reply-To: <CAADnVQLwpWMea1rbFAwvR_k+GzOphaOW-kUGORf90PJ-Ezxm4w@mail.gmail.com>
On Tue, 29 Sep 2020 at 16:48, Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
...
> There was a warning. I noticed it while applying and fixed it up.
> Lorenz, please upgrade your compiler. This is not the first time such
> warning has been missed.
I tried reproducing this on latest bpf-next (b0efc216f577997) with gcc
9.3.0 by removing the initialization of duration:
make: Entering directory '/home/lorenz/dev/bpf-next/tools/testing/selftests/bpf'
TEST-OBJ [test_progs] sockmap_basic.test.o
TEST-HDR [test_progs] tests.h
EXT-OBJ [test_progs] test_progs.o
EXT-OBJ [test_progs] cgroup_helpers.o
EXT-OBJ [test_progs] trace_helpers.o
EXT-OBJ [test_progs] network_helpers.o
EXT-OBJ [test_progs] testing_helpers.o
BINARY test_progs
make: Leaving directory '/home/lorenz/dev/bpf-next/tools/testing/selftests/bpf'
So, gcc doesn't issue a warning. Jakub did the following little experiment:
jkbs@toad ~/tmp $ cat warning.c
#include <stdio.h>
int main(void)
{
int duration;
fprintf(stdout, "%d", duration);
return 0;
}
jkbs@toad ~/tmp $ gcc -Wall -o /dev/null warning.c
warning.c: In function ‘main’:
warning.c:7:2: warning: ‘duration’ is used uninitialized in this
function [-Wuninitialized]
7 | fprintf(stdout, "%d", duration);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The simple case seems to work. However, adding the macro breaks things:
jkbs@toad ~/tmp $ cat warning.c
#include <stdio.h>
#define _CHECK(duration) \
({ \
fprintf(stdout, "%d", duration); \
})
#define CHECK() _CHECK(duration)
int main(void)
{
int duration;
CHECK();
return 0;
}
jkbs@toad ~/tmp $ gcc -Wall -o /dev/null warning.c
jkbs@toad ~/tmp $
Maybe this is https://gcc.gnu.org/bugzilla/show_bug.cgi?id=18501 ? The
problem is still there on gcc 10. Compiling test_progs with clang does
issue a warning FWIW, but it seems like other things break when doing
that.
--
Lorenz Bauer | Systems Engineer
6th Floor, County Hall/The Riverside Building, SE1 7PB, UK
www.cloudflare.com
next prev parent reply other threads:[~2020-09-30 9:28 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-28 9:08 [PATCH bpf-next v2 0/4] Sockmap copying Lorenz Bauer
2020-09-28 9:08 ` [PATCH bpf-next v2 1/4] bpf: sockmap: enable map_update_elem from bpf_iter Lorenz Bauer
2020-09-29 5:35 ` Martin KaFai Lau
2020-09-28 9:08 ` [PATCH bpf-next v2 2/4] selftests: bpf: Add helper to compare socket cookies Lorenz Bauer
2020-09-29 5:59 ` Martin KaFai Lau
2020-09-29 15:48 ` Alexei Starovoitov
2020-09-30 9:28 ` Lorenz Bauer [this message]
2020-10-01 7:23 ` Alexei Starovoitov
2020-10-01 17:09 ` Andrii Nakryiko
2020-10-01 17:11 ` Alexei Starovoitov
2020-10-02 10:08 ` Lorenz Bauer
2020-09-28 9:08 ` [PATCH bpf-next v2 3/4] selftests: bpf: remove shared header from sockmap iter test Lorenz Bauer
2020-09-28 9:08 ` [PATCH bpf-next v2 4/4] selftest: bpf: Test copying a sockmap and sockhash Lorenz Bauer
2020-09-29 6:06 ` Martin KaFai Lau
2020-09-29 9:21 ` Lorenz Bauer
2020-09-29 17:23 ` Martin KaFai Lau
2020-09-30 9:37 ` Lorenz Bauer
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='CACAyw98WzZGcFnnr7ELvbCziz2axJA_7x2mcoQTf2DYWDYJ=KA@mail.gmail.com' \
--to=lmb@cloudflare.com \
--cc=alexei.starovoitov@gmail.com \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=kafai@fb.com \
--cc=kernel-team@cloudflare.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=shuah@kernel.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.