linux-kernel - Re: [PATCH] perf test pmu: Remove unused test

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Message-ID: <ZqewJ6oIprdRY8C5@gallifrey>
Date: Mon, 29 Jul 2024 15:07:19 +0000
From: "Dr. David Alan Gilbert" <linux@...blig.org>
To: Ian Rogers <irogers@...gle.com>
Cc: kan.liang@...ux.intel.com, acme@...nel.org,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf test pmu: Remove unused test_pmus

* Ian Rogers (irogers@...gle.com) wrote:
> On Sat, Jul 27, 2024 at 10:59 AM <linux@...blig.org> wrote:
> >
> > From: "Dr. David Alan Gilbert" <linux@...blig.org>
> >
> > Commit aa1551f299ba ("perf test pmu: Refactor format test and exposed
> > test APIs") added the 'test_pmus' list, but didn't use it.
> > (It seems to put them on the other_pmus list?)
> >
> > Remove it.
> >
> > Signed-off-by: Dr. David Alan Gilbert <linux@...blig.org>
> 
> Strange that the compiler doesn't warn about unused stuff like this,
> we get unused variables within a function and unused static
> functions...

The problem is that LIST_HEAD initialises the list to point to itself;
so it *is* used - but only in it's own initialiser.
I did file:
   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115027

> Reviewed-by: Ian Rogers <irogers@...gle.com>

Thanks,

> Possibly:
> Fixes: aa1551f299ba ("perf test pmu: Refactor format test and exposed
> test APIs")

Given it's got no actual effect other than a few bytes
saved, I'm not sure it's worth the Fixes.

Dave

> Thanks,
> Ian
> 
> > ---
> >  tools/perf/tests/pmu.c | 3 ---
> >  1 file changed, 3 deletions(-)
> >
> > diff --git a/tools/perf/tests/pmu.c b/tools/perf/tests/pmu.c
> > index 40132655ccd1..0b2f04a55d7b 100644
> > --- a/tools/perf/tests/pmu.c
> > +++ b/tools/perf/tests/pmu.c
> > @@ -18,9 +18,6 @@
> >  #include <sys/stat.h>
> >  #include <sys/types.h>
> >
> > -/* Fake PMUs created in temp directory. */
> > -static LIST_HEAD(test_pmus);
> > -
> >  /* Cleanup test PMU directory. */
> >  static int test_pmu_put(const char *dir, struct perf_pmu *pmu)
> >  {
> > --
> > 2.45.2
> >
-- 
 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\        dave @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/