From db7fbf492d94a0b59d8f85b3184231662586dea9 Mon Sep 17 00:00:00 2001
From: George Prekas <prekageo@amazon.com>
Date: Thu, 25 Feb 2021 17:22:34 -0800
Subject: [PATCH] scripts/gdb: fix list_for_each

If the list is uninitialized (next pointer is NULL), list_for_each gets
stuck in an infinite loop. Print a message and treat list as empty.

Link: https://lkml.kernel.org/r/4ae23bb1-c333-f669-da2d-fa35c4f49018@amazon.com
Signed-off-by: George Prekas <prekageo@amazon.com>
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Kieran Bingham <kbingham@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 scripts/gdb/linux/lists.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/scripts/gdb/linux/lists.py b/scripts/gdb/linux/lists.py
index c487ddf09d38..bae4d70b7eae 100644
--- a/scripts/gdb/linux/lists.py
+++ b/scripts/gdb/linux/lists.py
@@ -27,6 +27,11 @@ def list_for_each(head):
         raise TypeError("Must be struct list_head not {}"
                            .format(head.type))
 
+    if head['next'] == 0:
+        gdb.write("list_for_each: Uninitialized list '{}' treated as empty\n"
+                     .format(head.address))
+        return
+
     node = head['next'].dereference()
     while node.address != head.address:
         yield node.address