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, 20 insertions, 0 deletions

diff --git a/fs/autofs/Kconfig b/fs/autofs/Kconfig
new file mode 100644
index 000000000..54c12d948
--- /dev/null
+++ b/fs/autofs/Kconfig
@@ -0,0 +1,20 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config AUTOFS_FS
+	tristate "Kernel automounter support (supports v3, v4 and v5)"
+	help
+	   The automounter is a tool to automatically mount remote file systems
+	   on demand. This implementation is partially kernel-based to reduce
+	   overhead in the already-mounted case; this is unlike the BSD
+	   automounter (amd), which is a pure user space daemon.
+
+	   To use the automounter you need the user-space tools from
+	   <https://www.kernel.org/pub/linux/daemons/autofs/>; you also want
+	   to answer Y to "NFS file system support", below.
+
+	   To compile this support as a module, choose M here: the module will be
+	   called autofs.
+
+	   If you are not a part of a fairly large, distributed network or
+	   don't have a laptop which needs to dynamically reconfigure to the
+	   local network, you probably do not need an automounter, and can say
+	   N here.