[tip: perf/core] perf tools: Avoid a malloc() for array events

[tip-bot2 for Ian Rogers]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     826100a7ce9a659b42140710ebe789d710799048
Gitweb:        https://git.kernel.org/tip/826100a7ce9a659b42140710ebe789d710799048
Author:        Ian Rogers <irogers@xxxxxxxxxx>
AuthorDate:    Tue, 22 Oct 2019 17:53:33 -07:00
Committer:     Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitterDate: Wed, 06 Nov 2019 15:43:05 -03:00

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@xxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
Cc: John Garry <john.garry@xxxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Martin KaFai Lau <kafai@xxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Song Liu <songliubraving@xxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Yonghong Song <yhs@xxxxxx>
Cc: bpf@xxxxxxxxxxxxxxx
Cc: clang-built-linux@xxxxxxxxxxxxxxxx
Cc: netdev@xxxxxxxxxxxxxxx
Link: http://lore.kernel.org/lkml/20191023005337.196160-6-irogers@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 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 5863acb..ffa1a1b 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;
 }