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, 85 insertions, 0 deletions

diff --git a/net/bridge/Kconfig b/net/bridge/Kconfig
new file mode 100644
index 000000000..318715c8f
--- /dev/null
+++ b/net/bridge/Kconfig
@@ -0,0 +1,85 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# 802.1d Ethernet Bridging
+#
+
+config BRIDGE
+	tristate "802.1d Ethernet Bridging"
+	select LLC
+	select STP
+	help
+	  If you say Y here, then your Linux box will be able to act as an
+	  Ethernet bridge, which means that the different Ethernet segments it
+	  is connected to will appear as one Ethernet to the participants.
+	  Several such bridges can work together to create even larger
+	  networks of Ethernets using the IEEE 802.1 spanning tree algorithm.
+	  As this is a standard, Linux bridges will cooperate properly with
+	  other third party bridge products.
+
+	  In order to use the Ethernet bridge, you'll need the bridge
+	  configuration tools; see <file:Documentation/networking/bridge.rst>
+	  for location. Please read the Bridge mini-HOWTO for more
+	  information.
+
+	  If you enable iptables support along with the bridge support then you
+	  turn your bridge into a bridging IP firewall.
+	  iptables will then see the IP packets being bridged, so you need to
+	  take this into account when setting up your firewall rules.
+	  Enabling arptables support when bridging will let arptables see
+	  bridged ARP traffic in the arptables FORWARD chain.
+
+	  To compile this code as a module, choose M here: the module
+	  will be called bridge.
+
+	  If unsure, say N.
+
+config BRIDGE_IGMP_SNOOPING
+	bool "IGMP/MLD snooping"
+	depends on BRIDGE
+	depends on INET
+	default y
+	help
+	  If you say Y here, then the Ethernet bridge will be able selectively
+	  forward multicast traffic based on IGMP/MLD traffic received from
+	  each port.
+
+	  Say N to exclude this support and reduce the binary size.
+
+	  If unsure, say Y.
+
+config BRIDGE_VLAN_FILTERING
+	bool "VLAN filtering"
+	depends on BRIDGE
+	depends on VLAN_8021Q
+	default n
+	help
+	  If you say Y here, then the Ethernet bridge will be able selectively
+	  receive and forward traffic based on VLAN information in the packet
+	  any VLAN information configured on the bridge port or bridge device.
+
+	  Say N to exclude this support and reduce the binary size.
+
+	  If unsure, say Y.
+
+config BRIDGE_MRP
+	bool "MRP protocol"
+	depends on BRIDGE
+	default n
+	help
+	  If you say Y here, then the Ethernet bridge will be able to run MRP
+	  protocol to detect loops
+
+	  Say N to exclude this support and reduce the binary size.
+
+	  If unsure, say N.
+
+config BRIDGE_CFM
+	bool "CFM protocol"
+	depends on BRIDGE
+	help
+	  If you say Y here, then the Ethernet bridge will be able to run CFM
+	  protocol according to 802.1Q section 12.14
+
+	  Say N to exclude this support and reduce the binary size.
+
+	  If unsure, say N.