ftrace: Synchronize the initialization of ftrace_opsgrafted

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 <rostedt@goodmis.org>

1 files changed, 42 insertions, 0 deletions

diff --git a/Documentation/networking/sctp.rst b/Documentation/networking/sctp.rst
new file mode 100644
index 000000000..9f4d9c8a9
--- /dev/null
+++ b/Documentation/networking/sctp.rst
@@ -0,0 +1,42 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=================
+Linux Kernel SCTP
+=================
+
+This is the current BETA release of the Linux Kernel SCTP reference
+implementation.
+
+SCTP (Stream Control Transmission Protocol) is a IP based, message oriented,
+reliable transport protocol, with congestion control, support for
+transparent multi-homing, and multiple ordered streams of messages.
+RFC2960 defines the core protocol.  The IETF SIGTRAN working group originally
+developed the SCTP protocol and later handed the protocol over to the
+Transport Area (TSVWG) working group for the continued evolvement of SCTP as a
+general purpose transport.
+
+See the IETF website (http://www.ietf.org) for further documents on SCTP.
+See http://www.ietf.org/rfc/rfc2960.txt
+
+The initial project goal is to create an Linux kernel reference implementation
+of SCTP that is RFC 2960 compliant and provides an programming interface
+referred to as the  UDP-style API of the Sockets Extensions for SCTP, as
+proposed in IETF Internet-Drafts.
+
+Caveats
+=======
+
+- lksctp can be built as statically or as a module.  However, be aware that
+  module removal of lksctp is not yet a safe activity.
+
+- There is tentative support for IPv6, but most work has gone towards
+  implementation and testing lksctp on IPv4.
+
+
+For more information, please visit the lksctp project website:
+
+   http://www.sf.net/projects/lksctp
+
+Or contact the lksctp developers through the mailing list:
+
+   <linux-sctp@vger.kernel.org>