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, 39 insertions, 0 deletions

diff --git a/net/mpls/Kconfig b/net/mpls/Kconfig
new file mode 100644
index 000000000..829fb1788
--- /dev/null
+++ b/net/mpls/Kconfig
@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# MPLS configuration
+#
+
+menuconfig MPLS
+	bool "MultiProtocol Label Switching"
+	default n
+	help
+	  MultiProtocol Label Switching routes packets through logical
+	  circuits.  Originally conceived as a way of routing packets at
+	  hardware speeds (before hardware was capable of routing ipv4 packets),
+	  MPLS remains a simple way of making tunnels.
+
+	  If you have not heard of MPLS you probably want to say N here.
+
+if MPLS
+
+config NET_MPLS_GSO
+	tristate "MPLS: GSO support"
+	help
+	 This is helper module to allow segmentation of non-MPLS GSO packets
+	 that have had MPLS stack entries pushed onto them and thus
+	 become MPLS GSO packets.
+
+config MPLS_ROUTING
+	tristate "MPLS: routing support"
+	depends on NET_IP_TUNNEL || NET_IP_TUNNEL=n
+	depends on SYSCTL
+	help
+	 Add support for forwarding of mpls packets.
+
+config MPLS_IPTUNNEL
+	tristate "MPLS: IP over MPLS tunnel support"
+	depends on LWTUNNEL && MPLS_ROUTING
+	help
+	 mpls ip tunnel support.
+
+endif # MPLS