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Message-ID: <5539A30A.8010600@weksteen.fr>
Date: Fri, 24 Apr 2015 11:57:30 +1000
From: Thiébaud Weksteen <thiebaud@...steen.fr>
To: linux-kernel@...r.kernel.org
CC: Jan Kiszka <jan.kiszka@...mens.com>
Subject: [PATCH v2] scripts/gdb: Add command to check list consistency
Add a gdb script to verify the consistency of lists.
Signed-off-by: Thiébaud Weksteen <thiebaud@...steen.fr>
---
Implement suggestions from Jan.
Changes in v2:
- Add copyright line
- Rename check_list to list_check
- Remove casting and only accept (struct list_head) object
- Add error message if argument is missing
- Reformat error messages to include address of nodes
Example of use:
(gdb) lx-list-check workqueues
Starting with: {next = 0xf3aea5a8, prev = 0xf580e668}
list is consistent: 30 node(s)
(gdb) set *((int *) 0xf3934908) = 0x0
(gdb) lx-list-check workqueues
Starting with: {next = 0xf3aea5a8, prev = 0xf580e668}
next is not accessible: current@...3934908={next = 0x0, prev = 0xf3aea5a8}
(gdb) set *((int *) 0xf3934908) = 0xdeadbeef
(gdb) lx-list-check workqueues
Starting with: {next = 0xf3aea5a8, prev = 0xf580e668}
next.prev != current: current@...3934908={next = 0xdeadbeef, prev = 0xf3aea5a8}
next@...eadbeef={next = 0x0, prev = 0x0}
(gdb) set *((int *) 0xf3934908) = 0xf537f188
(gdb) lx-list-check workqueues
Starting with: {next = 0xf3aea5a8, prev = 0xf580e668}
list is consistent: 30 node(s)
scripts/gdb/linux/lists.py | 89 ++++++++++++++++++++++++++++++++++++++++++++++
scripts/gdb/vmlinux-gdb.py | 1 +
2 files changed, 90 insertions(+)
create mode 100644 scripts/gdb/linux/lists.py
diff --git a/scripts/gdb/linux/lists.py b/scripts/gdb/linux/lists.py
new file mode 100644
index 0000000..2a94b54
--- /dev/null
+++ b/scripts/gdb/linux/lists.py
@@ -0,0 +1,89 @@
+#
+# gdb helper commands and functions for Linux kernel debugging
+#
+# list tools
+#
+# Copyright (c) Thiebaud Weksteen, 2015
+#
+# Authors:
+# Thiebaud Weksteen <thiebaud@...steen.fr>
+#
+# This work is licensed under the terms of the GNU GPL version 2.
+#
+
+import gdb
+
+from linux import utils
+
+list_head = utils.CachedType("struct list_head")
+
+
+def list_check(head):
+ nb = 0
+ c = head
+ if (c.type != list_head.get_type()):
+ raise gdb.GdbError('The argument should be of type (struct list_head)')
+ try:
+ gdb.write("Starting with: {}\n".format(c))
+ except gdb.MemoryError:
+ gdb.write('head is not accessible\n')
+ return
+ while True:
+ p = c['prev'].dereference()
+ n = c['next'].dereference()
+ try:
+ if p['next'] != c.address:
+ gdb.write('prev.next != current: '
+ 'current@...rrent_addr}={current} '
+ 'prev@...addr}={p}\n'.format(
+ current_addr=c.address,
+ current=c,
+ p_addr=p.address,
+ p=p,
+ ))
+ return
+ except gdb.MemoryError:
+ gdb.write('prev is not accessible: '
+ 'current@...rrent_addr}={current}\n'.format(
+ current_addr=c.address,
+ current=c
+ ))
+ return
+ try:
+ if n['prev'] != c.address:
+ gdb.write('next.prev != current: '
+ 'current@...rrent_addr}={current} '
+ 'next@...addr}={n}\n'.format(
+ current_addr=c.address,
+ current=c,
+ n_addr=n.address,
+ n=n,
+ ))
+ return
+ except gdb.MemoryError:
+ gdb.write('next is not accessible: '
+ 'current@...rrent_addr}={current}\n'.format(
+ current_addr=c.address,
+ current=c
+ ))
+ return
+ c = n
+ nb += 1
+ if c == head:
+ gdb.write("list is consistent: {} node(s)\n".format(nb))
+ return
+
+
+class LxListChk(gdb.Command):
+ """Verify a list consistency"""
+
+ def __init__(self):
+ super(LxListChk, self).__init__("lx-list-check", gdb.COMMAND_DATA)
+
+ def invoke(self, arg, from_tty):
+ argv = gdb.string_to_argv(arg)
+ if len(argv) != 1:
+ raise gdb.GdbError("lx-list-check takes one argument")
+ list_check(gdb.parse_and_eval(argv[0]))
+
+LxListChk()
diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py
index 4848928..ce82bf5 100644
--- a/scripts/gdb/vmlinux-gdb.py
+++ b/scripts/gdb/vmlinux-gdb.py
@@ -28,3 +28,4 @@ else:
import linux.dmesg
import linux.tasks
import linux.cpus
+ import linux.lists
--
2.1.0
--
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