[PATCH v2] scripts/gdb: fix list_for_each

From: George Prekas <prekageo@amazon.com>
To: Jan Kiszka <jan.kiszka@siemens.com>,
	Kieran Bingham <kbingham@kernel.org>
Cc: <linux-kernel@vger.kernel.org>
Subject: [PATCH v2] scripts/gdb: fix list_for_each
Date: Thu, 24 Sep 2020 09:20:56 -0500	[thread overview]
Message-ID: <4ae23bb1-c333-f669-da2d-fa35c4f49018@amazon.com> (raw)

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.

Signed-off-by: George Prekas <prekageo@amazon.com>
---
  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
-- 
2.16.6

