linux-kernel - Re: [PATCH v12 02/10] btf: Handle dynamic pointer parameter in kfuncs

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Message-ID: <Ywj3pOahYdxA8Dza@kernel.org>
Date:   Fri, 26 Aug 2022 19:41:45 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Roberto Sassu <roberto.sassu@...weicloud.com>
Cc:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        Mykola Lysenko <mykolal@...com>,
        Jonathan Corbet <corbet@....net>,
        David Howells <dhowells@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>,
        Paul Moore <paul@...l-moore.com>,
        James Morris <jmorris@...ei.org>,
        "Serge E . Hallyn" <serge@...lyn.com>,
        Shuah Khan <shuah@...nel.org>, bpf <bpf@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        keyrings@...r.kernel.org,
        LSM List <linux-security-module@...r.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Daniel Müller <deso@...teo.net>,
        Roberto Sassu <roberto.sassu@...wei.com>,
        Joanne Koong <joannelkoong@...il.com>
Subject: Re: [PATCH v12 02/10] btf: Handle dynamic pointer parameter in kfuncs

On Fri, Aug 26, 2022 at 07:32:54PM +0300, Jarkko Sakkinen wrote:
> On Fri, Aug 26, 2022 at 05:34:57PM +0200, Roberto Sassu wrote:
> > On Fri, 2022-08-26 at 17:43 +0300, Jarkko Sakkinen wrote:
> > > On Fri, Aug 26, 2022 at 08:46:14AM +0300, Jarkko Sakkinen wrote:
> > > > On Thu, Aug 25, 2022 at 10:16:14PM -0700, Alexei Starovoitov wrote:
> > > > > On Thu, Aug 25, 2022 at 9:54 PM Jarkko Sakkinen <
> > > > > jarkko@...nel.org> wrote:
> > > > > > > -static bool is_dynptr_reg_valid_init(struct bpf_verifier_env
> > > > > > > *env, struct bpf_reg_state *reg,
> > > > > > > -                                  enum bpf_arg_type
> > > > > > > arg_type)
> > > > > > > +bool is_dynptr_reg_valid_init(struct bpf_verifier_env *env,
> > > > > > > struct bpf_reg_state *reg,
> > > > > > > +                           enum bpf_arg_type arg_type)
> > > > > > >  {
> > > > > > >       struct bpf_func_state *state = func(env, reg);
> > > > > > >       int spi = get_spi(reg->off);
> > > > > > > --
> > > > > > > 2.25.1
> > > > > > > 
> > > > > > 
> > > > > > Might be niticking but generally I'd consider splitting
> > > > > > exports as commits of their own.
> > > > > 
> > > > > -static bool
> > > > > +bool
> > > > > 
> > > > > into a separate commit?
> > > > > 
> > > > > I guess it makes sense for people whose salary depends on
> > > > > number of commits.
> > > > > We don't play these games.
> > > > 
> > > > What kind of argument is that anyway.
> > > 
> > > "Separate each *logical change* into a separate patch." [*]
> > 
> > The logical change, as per the patch subject, is allowing the
> > possibility of including eBPF dynamic pointers in a kfunc definition.
> > It requires to call an existing function that was already defined
> > elsewhere.
> > 
> > Maybe I'm wrong, but I don't see only exporting a function definition
> > to an include file as a logical change. To me, the changes in this
> > patch are clearly connected. Or even better, they tell why the function
> > definition has been exported, that would not appear if moving the
> > function definition is a standalone patch.
> > 
> > > 
> > > To add, generally any user space visible space should be an
> > > isolated patch.
> > 
> > As far as I understood, definitions visible to user space should be in
> > include/uapi.
> 
> It does change e.g. the output of kallsyms.
> 
> It's not ABI but it's still user space visble.
> 
> > 
> > > 
> > > Please, stop posting nonsense.
> > 
> > If I may, saying this does not encourage people to try to submit their
> > code. I feel it is a bit strong, and I kindly ask you to express your
> > opinion in a more gentle way.
> 
> I agree. That's why I was wondering what is this nonsense
> about salary and games.

Please denote that I started my review with "Might be nitpicking...".

It's neither particularly disencouraging nor enforcing for anyone.

The blast that came after that, on the other hand, IMHO meets
exactly those standards.

BR, Jarkko