linux-kernel - Re: [PATCH] perf pmu: Fix event list for uncore PMUs

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Date:   Tue, 21 Dec 2021 10:35:57 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     John Garry <john.garry@...wei.com>
Cc:     peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        namhyung@...nel.org, irogers@...gle.com, kan.liang@...ux.intel.com,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf pmu: Fix event list for uncore PMUs

On Tue, Dec 21, 2021 at 09:10:37AM +0000, John Garry wrote:
> On 21/12/2021 07:58, Jiri Olsa wrote:
> > > +	/* Different names -> never duplicates */
> > > +	if (strcmp(alias_a->name, alias_b->name))
> > > +		return false;
> > > +	if (!alias_a->pmu)
> > > +		return true;
> > > +	if (!alias_b->pmu)
> > > +		return true;
> > nit could be:
> > 
> > 	if (!alias_a->pmu || !alias_b->pmu)
> > 		return true;
> > 
> > would be great to have more comments explaining the check
> > 
> 
> This is just a sanity check that both strings are non-NULL as we do a
> strcmp() next. So would this be better:
> 
> if (!alias_a->pmu || !alias_b->pmu || !strcmp(alias_a->pmu, alias_b->pmu))
> 	return true
> 
> ?
> 
> It will spill a line.

sure, it cought my eye because the is_cpu check later is done on
the same line, so I started wondering what's the difference ;-)

jirka

> 
> Thanks,
> John
> 
> > thanks,
> > jirka
> > 
> > > +	if (!strcmp(alias_a->pmu, alias_b->pmu))
> > > +		return true;
> > > +	/* uncore PMUs */
> 
>