netdev - [PATCH v4 3/9] perf tools: avoid a malloc for array events

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Date:   Fri, 25 Oct 2019 11:08:21 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andi Kleen <ak@...ux.intel.com>,
        Jin Yao <yao.jin@...ux.intel.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        John Garry <john.garry@...wei.com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, clang-built-linux@...glegroups.com
Cc:     Stephane Eranian <eranian@...gle.com>,
        Ian Rogers <irogers@...gle.com>
Subject: [PATCH v4 3/9] perf tools: avoid a malloc for array events

Use realloc rather than malloc+memcpy to possibly avoid a memory
allocation when appending array elements.

Signed-off-by: Ian Rogers <irogers@...gle.com>
---
 tools/perf/util/parse-events.y | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index 5863acb34780..ffa1a1b63796 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -689,14 +689,12 @@ array_terms ',' array_term
 	struct parse_events_array new_array;
 
 	new_array.nr_ranges = $1.nr_ranges + $3.nr_ranges;
-	new_array.ranges = malloc(sizeof(new_array.ranges[0]) *
-				  new_array.nr_ranges);
+	new_array.ranges = realloc($1.ranges,
+				sizeof(new_array.ranges[0]) *
+				new_array.nr_ranges);
 	ABORT_ON(!new_array.ranges);
-	memcpy(&new_array.ranges[0], $1.ranges,
-	       $1.nr_ranges * sizeof(new_array.ranges[0]));
 	memcpy(&new_array.ranges[$1.nr_ranges], $3.ranges,
 	       $3.nr_ranges * sizeof(new_array.ranges[0]));
-	free($1.ranges);
 	free($3.ranges);
 	$$ = new_array;
 }
-- 
2.24.0.rc0.303.g954a862665-goog