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, 52 insertions, 0 deletions

diff --git a/Documentation/admin-guide/LSM/tomoyo.rst b/Documentation/admin-guide/LSM/tomoyo.rst
new file mode 100644
index 000000000..bdb2c2e2a
--- /dev/null
+++ b/Documentation/admin-guide/LSM/tomoyo.rst
@@ -0,0 +1,52 @@
+======
+TOMOYO
+======
+
+What is TOMOYO?
+===============
+
+TOMOYO is a name-based MAC extension (LSM module) for the Linux kernel.
+
+LiveCD-based tutorials are available at
+
+https://tomoyo.sourceforge.net/1.8/ubuntu12.04-live.html
+https://tomoyo.sourceforge.net/1.8/centos6-live.html
+
+Though these tutorials use non-LSM version of TOMOYO, they are useful for you
+to know what TOMOYO is.
+
+How to enable TOMOYO?
+=====================
+
+Build the kernel with ``CONFIG_SECURITY_TOMOYO=y`` and pass ``security=tomoyo`` on
+kernel's command line.
+
+Please see https://tomoyo.sourceforge.net/2.6/ for details.
+
+Where is documentation?
+=======================
+
+User <-> Kernel interface documentation is available at
+https://tomoyo.sourceforge.net/2.6/policy-specification/index.html .
+
+Materials we prepared for seminars and symposiums are available at
+https://sourceforge.net/projects/tomoyo/files/docs/ .
+Below lists are chosen from three aspects.
+
+What is TOMOYO?
+  TOMOYO Linux Overview
+    https://sourceforge.net/projects/tomoyo/files/docs/lca2009-takeda.pdf
+  TOMOYO Linux: pragmatic and manageable security for Linux
+    https://sourceforge.net/projects/tomoyo/files/docs/freedomhectaipei-tomoyo.pdf
+  TOMOYO Linux: A Practical Method to Understand and Protect Your Own Linux Box
+    https://sourceforge.net/projects/tomoyo/files/docs/PacSec2007-en-no-demo.pdf
+
+What can TOMOYO do?
+  Deep inside TOMOYO Linux
+    https://sourceforge.net/projects/tomoyo/files/docs/lca2009-kumaneko.pdf
+  The role of "pathname based access control" in security.
+    https://sourceforge.net/projects/tomoyo/files/docs/lfj2008-bof.pdf
+
+History of TOMOYO?
+  Realities of Mainlining
+    https://sourceforge.net/projects/tomoyo/files/docs/lfj2008.pdf