[PATCH] perf: Fix dynamic field detection

[Frederic Weisbecker]

From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

Checking if a tracing field is an array with a dynamic length
requires to check the field type and seek the "__data_loc" string
that prepends the actual type, as can be found in a trace event
format file:

	field:__data_loc char[] name;	offset:16;	size:4;	signed:1;

But we actually use strcmp() to check if the field type fully
matches "__data_loc", which may fail as we trip over the rest of the
type.

To fix this, use strncmp to only check if it starts with "__data_loc".

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Tom Zanussi <tzanussi@xxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
---
 tools/perf/util/trace-event-parse.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/tools/perf/util/trace-event-parse.c b/tools/perf/util/trace-event-parse.c
index 17d6d66..d6ef414 100644
--- a/tools/perf/util/trace-event-parse.c
+++ b/tools/perf/util/trace-event-parse.c
@@ -761,7 +761,7 @@ static int field_is_string(struct format_field *field)
 
 static int field_is_dynamic(struct format_field *field)
 {
-	if (!strcmp(field->type, "__data_loc"))
+	if (!strncmp(field->type, "__data_loc", 10))
 		return 1;
 
 	return 0;
-- 
1.6.2.3

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