From: Ben Hutchings <ben@decadent.org.uk>
Date: Sun, 20 Mar 2016 21:09:02 +0000
Subject: tools lib traceevent: Fix use of uninitialized variables

Fix a number of correct warnings from gcc:

> plugin_function.c:133:6: warning: 'index' may be used uninitialized in this function [-Wmaybe-uninitialized]
>   int index;
>       ^

'index' is initialized only if indentation is wanted.  Move the
printing of indentation using 'index' into the same if-statement.

> kbuffer-parse.c:339:27: warning: 'length' may be used uninitialized in this function [-Wmaybe-uninitialized]
>   kbuf->next = kbuf->index + length;
>                            ^
> kbuffer-parse.c:297:15: note: 'length' was declared here
>   unsigned int length;
>                ^

'length' is not initialized when handling an OLD_RINGBUF_TYPE_TIME_EXTEND
record.  Based on what trace-cmd does, set length = 0 in this case.

> kbuffer-parse.c: In function 'kbuffer_read_at_offset':
> kbuffer-parse.c:632:9: warning: 'data' may be used uninitialized in this function [-Wmaybe-uninitialized]
>   return data;
>          ^

'data' is not initialized if the offset is too small.  Initialize it
to NULL so that the behaviour is the same as when the offset is too
large.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
--- a/tools/lib/traceevent/kbuffer-parse.c
+++ b/tools/lib/traceevent/kbuffer-parse.c
@@ -314,6 +314,7 @@ static unsigned int old_update_pointers(
 		extend <<= TS_SHIFT;
 		extend += delta;
 		delta = extend;
+		length = 0;
 		ptr += 4;
 		break;
 
@@ -613,7 +614,7 @@ unsigned long long kbuffer_timestamp(str
 void *kbuffer_read_at_offset(struct kbuffer *kbuf, int offset,
 			     unsigned long long *ts)
 {
-	void *data;
+	void *data = NULL;
 
 	if (offset < kbuf->start)
 		offset = 0;
--- a/tools/lib/traceevent/plugin_function.c
+++ b/tools/lib/traceevent/plugin_function.c
@@ -142,10 +142,10 @@ static int function_handler(struct trace
 
 	parent = pevent_find_function(pevent, pfunction);
 
-	if (parent && ftrace_indent->set)
+	if (parent && ftrace_indent->set) {
 		index = add_and_get_index(parent, func, record->cpu);
-
-	trace_seq_printf(s, "%*s", index*3, "");
+		trace_seq_printf(s, "%*s", index*3, "");
+	}
 
 	if (func)
 		trace_seq_printf(s, "%s", func);
