[tip:perf/core] tools lib traceevent: Initialize lenght on OLD_RING_BUFFER_TYPE_TIME_STAMP

[tip-bot for Steven Rostedt (VMware)]

Commit-ID:  14e4d7e0abfdefabea2b8796c5a8b2b9c77b5326
Gitweb:     http://git.kernel.org/tip/14e4d7e0abfdefabea2b8796c5a8b2b9c77b5326
Author:     Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
AuthorDate: Mon, 13 Feb 2017 12:11:44 -0500
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 13 Feb 2017 17:22:32 -0300

tools lib traceevent: Initialize lenght on OLD_RING_BUFFER_TYPE_TIME_STAMP

A undefined value was being used for the OLD_RING_BUFFER_TYPE_TIME_STAMP
case entry, as the 'length' variable was not being initialized, fix it.

Caught by the reporter when building tools/perf/ using clang, which emmitted
this warning:

  kbuffer-parse.c:312:7: warning: variable 'length' is used uninitialized whenever switch case is taken [-Wsometimes-uninitialized]
          case OLD_RINGBUF_TYPE_TIME_EXTEND:
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
  kbuffer-parse.c:339:29: note: uninitialized use occurs here
          kbuf->next = kbuf->index + length;
                                   ^~~~~~
  kbuffer-parse.c:297:21: note: initialize the variable 'length' to silence this warning
          unsigned int length;
                             ^
                              = 0

Reported-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/20170213121418.47f279e8@xxxxxxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/lib/traceevent/kbuffer-parse.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/lib/traceevent/kbuffer-parse.c b/tools/lib/traceevent/kbuffer-parse.c
index 65984f1..c94e364 100644
--- a/tools/lib/traceevent/kbuffer-parse.c
+++ b/tools/lib/traceevent/kbuffer-parse.c
@@ -315,6 +315,7 @@ static unsigned int old_update_pointers(struct kbuffer *kbuf)
 		extend += delta;
 		delta = extend;
 		ptr += 4;
+		length = 0;
 		break;
 
 	case OLD_RINGBUF_TYPE_TIME_STAMP: