netdev - Re: [PATCH v3 bpf-next 04/19] bpf: refactor "check_reg

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Date:   Sat, 13 Apr 2019 08:00:59 +0100
From:   Jiong Wang <jiong.wang@...ronome.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Jiong Wang <jiong.wang@...ronome.com>, daniel@...earbox.net,
        bpf@...r.kernel.org, netdev@...r.kernel.org,
        oss-drivers@...ronome.com
Subject: Re: [PATCH v3 bpf-next 04/19] bpf: refactor "check_reg_arg" to eliminate code redundancy

Alexei Starovoitov writes:

> On Fri, Apr 12, 2019 at 10:59:37PM +0100, Jiong Wang wrote:
>> There are a few "regs[regno]" here are there across "check_reg_arg", this
>> patch factor it out into a simple "reg" pointer. The intention is to
>> simplify code indentation and make the later patches in this set look
>> cleaner.
>> 
>> Reviewed-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
>> Signed-off-by: Jiong Wang <jiong.wang@...ronome.com>
>
> The first 4 patches look great, so I've applied them to bpf-next.

Thanks.

> The rest needs more careful review that we'll do soon.

No problem and agree they need very careful review. I understand once
landed the optimization will be always on for a couple of targets like Arm,
PowerPC and SPARC etc, so the correctness is critical.

Patch 5 has two comments from Jakub not addressed, they are not about
correctness so should not affect the review, I will fix them together with
the other new comments.

One good thing is high 32-bit randomization does catch a couple of corner
case bugs so prove to be very powerful and efficient for exposing bugs. In
v3, it is enabled on all possible tests under bpf selftests, and I haven't
noticed regressions (my local machine configure may caused some tests
skipped, but majority of the testsuite, especially all tests under
test_progs/test_progs_32/test_verifier ran without failure), this is a good
assurance of correctness.

Thanks.

Regards,
Jiong