linux-kernel - Re: [PATCH v3] tools/perf/metricgroup: Fix printing event names of metric group with multiple events incase of overlapping events

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Message-ID: <51a4b570eb47e80801a460c89acf20d13a269600.camel@perches.com>
Date:   Thu, 06 Feb 2020 10:58:12 -0800
From:   Joe Perches <joe@...ches.com>
To:     Jiri Olsa <jolsa@...hat.com>, Kajol Jain <kjain@...ux.ibm.com>
Cc:     acme@...nel.org, linux-kernel@...r.kernel.org,
        linux-perf-users@...r.kernel.org, Jiri Olsa <jolsa@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jin Yao <yao.jin@...ux.intel.com>,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>,
        Anju T Sudhakar <anju@...ux.vnet.ibm.com>,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: Re: [PATCH v3] tools/perf/metricgroup: Fix printing event names of
 metric group with multiple events incase of overlapping events

On Thu, 2020-02-06 at 19:45 +0100, Jiri Olsa wrote:
> On Fri, Jan 31, 2020 at 10:55:22AM +0530, Kajol Jain wrote:
> 
> SNIP
> 
> >  				ev->metric_leader = metric_events[i];
> >  			}
> > +			j++;
> >  		}
> > +		ev = metric_events[i];
> > +		evlist_used[ev->idx] = true;
> >  	}
> >  
> >  	return metric_events[0];
> > @@ -160,6 +161,9 @@ static int metricgroup__setup_events(struct list_head *groups,
> >  	int ret = 0;
> >  	struct egroup *eg;
> >  	struct evsel *evsel;
> > +	bool evlist_used[perf_evlist->core.nr_entries];
> > +
> > +	memset(evlist_used, 0, perf_evlist->core.nr_entries);
> 
> I know I posted this in the previous email, but are we sure bool
> is always 1 byte?  would sizeod(evlist_used) be safer?
> 
> other than that it looks ok
> 
> Andi, you're ok with this?

stack declarations of variable length arrays are not
a good thing.

https://lwn.net/Articles/749089/

and

	bool evlist_used[perf_evlist->core.nr_entries] = {};

would be better.