From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- Documentation/networking/x25.rst | 46 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 Documentation/networking/x25.rst (limited to 'Documentation/networking/x25.rst') diff --git a/Documentation/networking/x25.rst b/Documentation/networking/x25.rst new file mode 100644 index 000000000..e11d9ebdf --- /dev/null +++ b/Documentation/networking/x25.rst @@ -0,0 +1,46 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================== +Linux X.25 Project +================== + +As my third year dissertation at University I have taken it upon myself to +write an X.25 implementation for Linux. My aim is to provide a complete X.25 +Packet Layer and a LAPB module to allow for "normal" X.25 to be run using +Linux. There are two sorts of X.25 cards available, intelligent ones that +implement LAPB on the card itself, and unintelligent ones that simply do +framing, bit-stuffing and checksumming. These both need to be handled by the +system. + +I therefore decided to write the implementation such that as far as the +Packet Layer is concerned, the link layer was being performed by a lower +layer of the Linux kernel and therefore it did not concern itself with +implementation of LAPB. Therefore the LAPB modules would be called by +unintelligent X.25 card drivers and not by intelligent ones, this would +provide a uniform device driver interface, and simplify configuration. + +To confuse matters a little, an 802.2 LLC implementation is also possible +which could allow X.25 to be run over an Ethernet (or Token Ring) and +conform with the JNT "Pink Book", this would have a different interface to +the Packet Layer but there would be no confusion since the class of device +being served by the LLC would be completely separate from LAPB. + +Just when you thought that it could not become more confusing, another +option appeared, XOT. This allows X.25 Packet Layer frames to operate over +the Internet using TCP/IP as a reliable link layer. RFC1613 specifies the +format and behaviour of the protocol. If time permits this option will also +be actively considered. + +A linux-x25 mailing list has been created at vger.kernel.org to support the +development and use of Linux X.25. It is early days yet, but interested +parties are welcome to subscribe to it. Just send a message to +majordomo@vger.kernel.org with the following in the message body: + +subscribe linux-x25 +end + +The contents of the Subject line are ignored. + +Jonathan + +g4klx@g4klx.demon.co.uk -- cgit v1.3.1