netdev - Re: [PATCH v8 bpf-next 02/13] tools resolve_btfids: Add support for set symbols

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Date:   Tue, 28 Jul 2020 11:35:53 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Jiri Olsa <jolsa@...nel.org>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andriin@...com>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Martin KaFai Lau <kafai@...com>,
        David Miller <davem@...hat.com>,
        John Fastabend <john.fastabend@...il.com>,
        Wenbo Zhang <ethercflow@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Brendan Gregg <bgregg@...flix.com>,
        Florent Revest <revest@...omium.org>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH v8 bpf-next 02/13] tools resolve_btfids: Add support for
 set symbols

On Mon, Jul 27, 2020 at 05:53:01PM -0700, Andrii Nakryiko wrote:
> On Wed, Jul 22, 2020 at 2:13 PM Jiri Olsa <jolsa@...nel.org> wrote:
> >
> > The set symbol does not have the unique number suffix,
> > so we need to give it a special parsing function.
> >
> > This was omitted in the first batch, because there was
> > no set support yet, so it slipped in the testing.
> >
> > Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> > ---
> >  tools/bpf/resolve_btfids/main.c | 15 ++++++++++++++-
> >  1 file changed, 14 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
> > index 6956b6350cad..c28ab0401818 100644
> > --- a/tools/bpf/resolve_btfids/main.c
> > +++ b/tools/bpf/resolve_btfids/main.c
> > @@ -220,6 +220,19 @@ static char *get_id(const char *prefix_end)
> >         return id;
> >  }
> >
> > +static struct btf_id *add_set(struct object *obj, char *name)
> > +{
> > +       char *id;
> > +
> > +       id = strdup(name + sizeof(BTF_SET) + sizeof("__") - 2);
> 
> why strdup? you are not really managing memory carefully anyway,
> letting OS clean everything up, so why bother strduping here?

it copies the get_id logic, where we cut the unique ID part,
but we don't cut the string in here, so no reason for strdup
I'll remove it

> 
> Also if get invalid identifier, you can easily go past the string and
> its ending zero byte. So check strlen first?

right.. it's also missing in get_id funciton, will add

thanks,
jirka

> 
> > +       if (!id) {
> > +               pr_err("FAILED to parse cnt name: %s\n", name);
> > +               return NULL;
> > +       }
> > +
> > +       return btf_id__add(&obj->sets, id, true);
> > +}
> > +

SNIP