linux-kernel - [PATCH 1/3] perf tools: Fix cpu conversion in cpu_map__from

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Date:	Wed,  6 Jan 2016 11:49:55 +0100
From:	Jiri Olsa <jolsa@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	"Liang, Kan" <kan.liang@...el.com>
Subject: [PATCH 1/3] perf tools: 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).

Link: http://lkml.kernel.org/n/tip-6t5lp407ca76zlikz9rl2lcm@git.kernel.org
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 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 a0717b93d8f5..fa935093a599 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;
-- 
2.4.3

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