lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Fri, 21 Aug 2020 11:47:28 +0100
From:   Tom Parkin <>
Cc:, Tom Parkin <>
Subject: [PATCH 9/9] docs: networking: add tracepoint info to l2tp.rst

Update l2tp.rst to:

 * remove information about the obsolete debug flags and their use
 * include information about tracepoints for l2tp

Signed-off-by: Tom Parkin <>
 Documentation/networking/l2tp.rst | 37 ++++++++++++-------------------
 1 file changed, 14 insertions(+), 23 deletions(-)

diff --git a/Documentation/networking/l2tp.rst b/Documentation/networking/l2tp.rst
index 693ea0e3ec26..498b382d25a0 100644
--- a/Documentation/networking/l2tp.rst
+++ b/Documentation/networking/l2tp.rst
@@ -455,31 +455,16 @@ l2tp help`` for more information.
-The L2TP subsystem offers a debug scheme where kernel trace messages
-may be optionally enabled per tunnel and per session. Care is needed
-when debugging a live system since the messages are not rate-limited
-and a busy system could be swamped. Userspace uses setsockopt on the
-PPPoX socket to set a debug mask, or ``L2TP_ATTR_DEBUG`` in netlink
-Create and Modify commands.
+The L2TP subsystem offers a range of debugging interfaces through the
+debugfs filesystem.
-The following debug mask bits are defined:-
-================  ==============================
-L2TP_MSG_DEBUG    verbose debug (if compiled in)
-L2TP_MSG_CONTROL  userspace - kernel interface
-L2TP_MSG_SEQ      sequence numbers handling
-L2TP_MSG_DATA     data packets
-================  ==============================
-Sessions inherit default debug flags from the parent tunnel.
-If enabled, files under a l2tp debugfs directory can be used to dump
-kernel state about L2TP tunnels and sessions. To access it, the
-debugfs filesystem must first be mounted::
+To access these interfaces, the debugfs filesystem must first be mounted::
     # mount -t debugfs debugfs /debug
-Files under the l2tp directory can then be accessed::
+Files under the l2tp directory can then be accessed, providing a summary
+of the current population of tunnel and session contexts existing in the
     # cat /debug/l2tp/tunnels
@@ -488,8 +473,14 @@ state information because the file format is subject to change. It is
 implemented to provide extra debug information to help diagnose
 problems. Applications should instead use the netlink API.
-/proc/net/pppol2tp is also provided for backwards compatibility with
-the original pppol2tp code. It lists information about L2TPv2
+In addition the L2TP subsystem implements tracepoints using the standard
+kernel event tracing API.  The available L2TP events can be reviewed as
+    # find /debug/tracing/events/l2tp
+Finally, /proc/net/pppol2tp is also provided for backwards compatibility
+with the original pppol2tp code. It lists information about L2TPv2
 tunnels and sessions only. Its use is discouraged.
 Internal Implementation

Powered by blists - more mailing lists