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>

diff --git a/scripts/gdb/linux/lists.py b/scripts/gdb/linux/lists.py
index c487ddf..bae4d70 100644 (file)
--- 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