[PATCH v5 4/9] perf libdw: Fix callchain parent update in ORDER_CALLER mode

[Ian Rogers <irogers@google.com>]

Fix the parent srcline lookup in `libdw_a2l_cb()` to target the
correct parent node depending on the callchain order
(ORDER_CALLER/ORDER_CALLEE).

This ensures inline callchains are not corrupted when nest depth > 2.

Signed-off-by: Ian Rogers <irogers@google.com>
---
v5:
 - Split from original Patch 3/6 into its own commit.
 - Fixed bisectability failure by removing unused `ilist` variable declaration.
---
 tools/perf/util/libdw.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/libdw.c b/tools/perf/util/libdw.c
index 216977884103..301642084c69 100644
--- a/tools/perf/util/libdw.c
+++ b/tools/perf/util/libdw.c
@@ -4,6 +4,7 @@
 #include "srcline.h"
 #include "symbol.h"
 #include "dwarf-aux.h"
+#include "callchain.h"
 #include <fcntl.h>
 #include <unistd.h>
 #include <elfutils/libdwfl.h>
@@ -80,7 +81,6 @@ static int libdw_a2l_cb(Dwarf_Die *die, void *_args)
 	struct symbol *inline_sym = new_inline_sym(args->dso, args->sym, dwarf_diename(die));
 	const char *call_fname = die_get_call_file(die);
 	char *call_srcline = srcline__unknown;
-	struct inline_list *ilist;
 
 	if (!inline_sym)
 		return -ENOMEM;
@@ -89,14 +89,20 @@ static int libdw_a2l_cb(Dwarf_Die *die, void *_args)
 	if (call_fname)
 		call_srcline = srcline_from_fileline(call_fname, die_get_call_lineno(die));
 
-	list_for_each_entry(ilist, &args->node->val, list) {
-		if (args->leaf_srcline == ilist->srcline)
+	if (!list_empty(&args->node->val)) {
+		struct inline_list *parent;
+
+		if (callchain_param.order == ORDER_CALLEE)
+			parent = list_first_entry(&args->node->val, struct inline_list, list);
+		else
+			parent = list_last_entry(&args->node->val, struct inline_list, list);
+
+		if (args->leaf_srcline == parent->srcline)
 			args->leaf_srcline_used = false;
-		else if (ilist->srcline != srcline__unknown)
-			free(ilist->srcline);
-		ilist->srcline =  call_srcline;
+		else if (parent->srcline != srcline__unknown)
+			free(parent->srcline);
+		parent->srcline = call_srcline;
 		call_srcline = NULL;
-		break;
 	}
 	if (call_srcline && call_srcline != srcline__unknown)
 		free(call_srcline);
-- 
2.54.0.545.g6539524ca2-goog