[tip:perf/core] perf cpumap: Fix cpu conversion in cpu_map__from_entries

[tip-bot for Jiri Olsa]

Commit-ID:  15d2b9956b41ffb5961b897bf61cdc09f722dfbf
Gitweb:     http://git.kernel.org/tip/15d2b9956b41ffb5961b897bf61cdc09f722dfbf
Author:     Jiri Olsa <jolsa@xxxxxxxxxx>
AuthorDate: Wed, 6 Jan 2016 11:49:55 +0100
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Wed, 6 Jan 2016 20:11:16 -0300

perf cpumap: Fix cpu conversion in cpu_map__from_entries

We can't convert u16 cpu_map_entries::cpu[x] value directly to int,
because it could hold -1, which would be converted as 65535.

Adding special treatment for -1, which is not real cpu number, to be
converted to (int -1).

Reported-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1452077397-31958-2-git-send-email-jolsa@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/cpumap.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/cpumap.c b/tools/perf/util/cpumap.c
index a0717b9..fa93509 100644
--- a/tools/perf/util/cpumap.c
+++ b/tools/perf/util/cpumap.c
@@ -188,8 +188,17 @@ static struct cpu_map *cpu_map__from_entries(struct cpu_map_entries *cpus)
 	if (map) {
 		unsigned i;
 
-		for (i = 0; i < cpus->nr; i++)
-			map->map[i] = (int)cpus->cpu[i];
+		for (i = 0; i < cpus->nr; i++) {
+			/*
+			 * Special treatment for -1, which is not real cpu number,
+			 * and we need to use (int) -1 to initialize map[i],
+			 * otherwise it would become 65535.
+			 */
+			if (cpus->cpu[i] == (u16) -1)
+				map->map[i] = -1;
+			else
+				map->map[i] = (int) cpus->cpu[i];
+		}
 	}
 
 	return map;