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, 37 insertions, 0 deletions

diff --git a/net/atm/Kconfig b/net/atm/Kconfig
new file mode 100644
index 000000000..dfdc3a855
--- /dev/null
+++ b/net/atm/Kconfig
@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Asynchronous Transfer Mode (ATM)
+#
+
+config ATM
+	tristate "Asynchronous Transfer Mode (ATM)"
+	help
+	  ATM is a high-speed networking technology for Local Area Networks
+	  and Wide Area Networks.  It uses a fixed packet size and is
+	  connection oriented, allowing for the negotiation of minimum
+	  bandwidth requirements.
+
+	  In order to participate in an ATM network, your Linux box needs an
+	  ATM networking card. If you have that, say Y here and to the driver
+	  of your ATM card below.
+
+	  Note that you need a set of user-space programs to actually make use
+	  of ATM.  See the file <file:Documentation/networking/atm.rst> for
+	  further details.
+
+config ATM_BR2684
+	tristate "RFC1483/2684 Bridged protocols"
+	depends on ATM && INET
+	help
+	  ATM PVCs can carry ethernet PDUs according to RFC2684 (formerly 1483)
+	  This device will act like an ethernet from the kernels point of view,
+	  with the traffic being carried by ATM PVCs (currently 1 PVC/device).
+	  This is sometimes used over DSL lines.  If in doubt, say N.
+
+config ATM_BR2684_IPFILTER
+	bool "Per-VC IP filter kludge"
+	depends on ATM_BR2684
+	help
+	  This is an experimental mechanism for users who need to terminate a
+	  large number of IP-only vcc's.  Do not enable this unless you are sure
+	  you know what you are doing.