netdev - Re: [bpf-next 1/2] samples: bpf: Fix tracex7 error raised on the missing argument

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Message-ID: <CAK+SQuTQ7OfxCLzrwtV6K7-Kug6ZL+11=_f+hBgNteKtqnXGYw@mail.gmail.com>
Date:   Tue, 27 Jul 2021 12:32:41 +0900
From:   Juhee Kang <claudiajkang@...il.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>
Subject: Re: [bpf-next 1/2] samples: bpf: Fix tracex7 error raised on the
 missing argument

On Tue, Jul 27, 2021 at 5:08 AM Andrii Nakryiko
<andrii.nakryiko@...il.com> wrote:
>
> On Sat, Jul 24, 2021 at 8:21 AM Juhee Kang <claudiajkang@...il.com> wrote:
> >
> > The current behavior of 'tracex7' doesn't consist with other bpf samples
> > tracex{1..6}. Other samples do not require any argument to run with, but
> > tracex7 should be run with btrfs device argument. (it should be executed
> > with test_override_return.sh)
> >
> > Currently, tracex7 doesn't have any description about how to run this
> > program and raises an unexpected error. And this result might be
> > confusing since users might not have a hunch about how to run this
> > program.
> >
> >     // Current behavior
> >     # ./tracex7
> >     sh: 1: Syntax error: word unexpected (expecting ")")
> >     // Fixed behavior
> >     # ./tracex7
> >     ERROR: Run with the btrfs device argument!
> >
> > In order to fix this error, this commit adds logic to report a message
> > and exit when running this program with a missing argument.
> >
> > Additionally in test_override_return.sh, there is a problem with
> > multiple directory(tmpmnt) creation. So in this commit adds a line with
> > removing the directory with every execution.
> >
> > Signed-off-by: Juhee Kang <claudiajkang@...il.com>
> > ---
> >  samples/bpf/test_override_return.sh | 1 +
> >  samples/bpf/tracex7_user.c          | 5 +++++
> >  2 files changed, 6 insertions(+)
> >
> > diff --git a/samples/bpf/test_override_return.sh b/samples/bpf/test_override_return.sh
> > index e68b9ee6814b..6480b55502c7 100755
> > --- a/samples/bpf/test_override_return.sh
> > +++ b/samples/bpf/test_override_return.sh
> > @@ -1,5 +1,6 @@
> >  #!/bin/bash
> >
> > +rm -rf tmpmnt
>
> Do we need -rf or -r would do?
>

It works properly using only -r.
Thanks for pointing it out! I will stick to this method.

I will send the next version as soon as possible.

> >  rm -f testfile.img
> >  dd if=/dev/zero of=testfile.img bs=1M seek=1000 count=1
> >  DEVICE=$(losetup --show -f testfile.img)
> > diff --git a/samples/bpf/tracex7_user.c b/samples/bpf/tracex7_user.c
> > index fdcd6580dd73..8be7ce18d3ba 100644
> > --- a/samples/bpf/tracex7_user.c
> > +++ b/samples/bpf/tracex7_user.c
> > @@ -14,6 +14,11 @@ int main(int argc, char **argv)
> >         int ret = 0;
> >         FILE *f;
> >
> > +       if (!argv[1]) {
> > +               fprintf(stderr, "ERROR: Run with the btrfs device argument!\n");
> > +               return 0;
> > +       }
> > +
> >         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
> >         obj = bpf_object__open_file(filename, NULL);
> >         if (libbpf_get_error(obj)) {
> > --
> > 2.27.0
> >



-- 

Best regards,
Juhee Kang