From: Michael Ellerman <mpe@ellerman.id.au>
To: Arseny Solokha <asolokha@kb.kras.ru>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Scott Wood <scottwood@freescale.com>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/4] powerpc/mpic: remove unused functions
Date: Fri, 20 Feb 2015 14:34:32 +1100 [thread overview]
Message-ID: <1424403272.26444.1.camel@ellerman.id.au> (raw)
In-Reply-To: <87d256kry8.fsf@KB00016249.iskra.kb>
On Thu, 2015-02-19 at 19:26 +0700, Arseny Solokha wrote:
> > On Mon, 2015-02-16 at 17:56 +0700, Arseny Solokha wrote:
> >> Drop unused fsl_mpic_primary_get_version(), mpic_set_clk_ratio(),
> >> mpic_set_serial_int().
> >
> > I'm always happy to remove unused code, but the interesting question is why are
> > they unused? Please tell me in the changelog.
>
> To being able to give a definitive answer, it's necessary to understand
> the intentions of original developers of these pieces. I just can tell
> these functions have no users and trivial grepping easily proves it;
> I've got the impression they are here only for the sake of
> implementation completeness.
Yeah OK. I didn't expect you to read the minds of the developers who wrote the
code :)
> Two machines at hands, e300 and e500 based, boot and run without
> regressions on my workload with this series applied. The removed code
> seems also been rarely touched, so it seems the series is safe at least
> in general. But I can't obviously express any strong point in support of
> the series, so it's completely OK to leave things as is.
OK that's a good data point.
> + fsl_mpic_primary_get_version() is just a safe wrapper around
> fsl_mpic_get_version() for SMP configurations. While the latter is
> called explicitly for handling PIC initialization and setting up error
> interrupt vector depending on PIC hardware version, the former isn't
> used for anything.
>
> + As for mpic_set_clk_ratio() and mpic_set_serial_int(), they both
> are almost nine years old[1] but still have no chance to be called even
> from out-of-tree modules because they both are __init and of course
> aren't exported. Non-demanded functionality?
>
> Of course I'll include the last two paragraphs into the V2 patch
> description if the explanation is convincing enough and you ACK it. If
> the patch is safe it's also necessary to extend it a bit, making its
> second part actually a complete revert of [1].
>
> [1] https://lists.ozlabs.org/pipermail/linuxppc-dev/2006-June/023867.html
That is more like what I was looking for.
If I just get a patch saying "removed unused foo()", I have to go and dig and
find out:
- was it recently added and will be used soon?
- is it ancient and never used, if so can we work out why, ie. feature X
never landed so this code is no longer needed.
- is it old code that *was* used but isn't now because commit ... removed the
last user.
- is it code that *should* be used, but isn't for some odd reason?
So if you can provide that sort of detail for me, that really adds value to the
patch. Otherwise the patch is basically just a TODO for me, to go and work out
why the code is unused.
cheers
next prev parent reply other threads:[~2015-02-20 3:34 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-16 10:56 [PATCH 0/4] powerpc: trivial unused functions cleanup Arseny Solokha
2015-02-16 10:56 ` [PATCH 1/4] powerpc/boot: drop planetcore_set_serial_speed Arseny Solokha
2015-02-16 10:56 ` [PATCH 2/4] kvm/ppc/mpic: drop unused IRQ_testbit Arseny Solokha
2015-02-16 10:56 ` [PATCH 3/4] powrepc/qe: drop unused ucc_slow_poll_transmitter_now Arseny Solokha
2015-02-16 10:56 ` [PATCH 4/4] powerpc/mpic: remove unused functions Arseny Solokha
2015-02-19 0:58 ` Michael Ellerman
2015-02-19 12:26 ` Arseny Solokha
2015-02-20 3:34 ` Michael Ellerman [this message]
2015-02-20 4:40 ` Arseny Solokha
2015-02-24 4:48 ` Michael Ellerman
2015-02-23 21:31 ` Scott Wood
2015-02-26 2:39 ` Hongtao Jia
2015-02-26 3:27 ` Scott Wood
2015-02-24 9:05 ` [PATCH V2 0/4] powerpc: trivial unused functions cleanup Arseny Solokha
2015-02-24 9:05 ` [PATCH 1/4] powerpc/boot: drop planetcore_set_serial_speed Arseny Solokha
2015-02-24 9:05 ` [PATCH 2/4] kvm/ppc/mpic: drop unused IRQ_testbit Arseny Solokha
2015-02-24 9:05 ` [PATCH 3/4] powrepc/qe: drop unused ucc_slow_poll_transmitter_now Arseny Solokha
2015-02-24 9:05 ` [PATCH 4/4] powerpc/mpic: remove unused functions Arseny Solokha
2015-02-27 2:25 ` Arseny Solokha
2015-03-20 3:56 ` [PATCH v3 0/4] powerpc: trivial unused functions cleanup Arseny Solokha
2015-03-20 3:56 ` [PATCH 1/4] powerpc/boot: drop planetcore_set_serial_speed Arseny Solokha
2015-03-20 3:56 ` [PATCH 2/4] kvm/ppc/mpic: drop unused IRQ_testbit Arseny Solokha
2015-03-20 11:41 ` Alexander Graf
2015-03-21 6:56 ` [PATCH v4 " Arseny Solokha
2015-03-21 14:54 ` Alexander Graf
2015-03-20 3:56 ` [PATCH 3/4] powrepc/qe: drop unused ucc_slow_poll_transmitter_now Arseny Solokha
2015-03-20 3:56 ` [PATCH 4/4] powerpc/mpic: remove unused functions Arseny Solokha
2015-03-20 4:23 ` [PATCH v3 0/4] powerpc: trivial unused functions cleanup Michael Ellerman
2015-03-20 4:55 ` Arseny Solokha
2015-03-20 5:39 ` Michael Ellerman
2015-03-21 6:56 ` Arseny Solokha
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