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, 73 insertions, 0 deletions

diff --git a/net/can/Kconfig b/net/can/Kconfig
new file mode 100644
index 000000000..abbb4be7a
--- /dev/null
+++ b/net/can/Kconfig
@@ -0,0 +1,73 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Controller Area Network (CAN) network layer core configuration
+#
+
+menuconfig CAN
+	tristate "CAN bus subsystem support"
+	select SKB_EXTENSIONS
+	help
+	  Controller Area Network (CAN) is a slow (up to 1Mbit/s) serial
+	  communications protocol. Development of the CAN bus started in
+	  1983 at Robert Bosch GmbH, and the protocol was officially
+	  released in 1986. The CAN bus was originally mainly for automotive,
+	  but is now widely used in marine (NMEA2000), industrial, and medical
+	  applications. More information on the CAN network protocol family
+	  PF_CAN is contained in <Documentation/networking/can.rst>.
+
+	  If you want CAN support you should say Y here and also to the
+	  specific driver for your controller(s) under the Network device
+	  support section.
+
+if CAN
+
+config CAN_RAW
+	tristate "Raw CAN Protocol (raw access with CAN-ID filtering)"
+	default y
+	help
+	  The raw CAN protocol option offers access to the CAN bus via
+	  the BSD socket API. You probably want to use the raw socket in
+	  most cases where no higher level protocol is being used. The raw
+	  socket has several filter options e.g. ID masking / error frames.
+	  To receive/send raw CAN messages, use AF_CAN with protocol CAN_RAW.
+
+config CAN_BCM
+	tristate "Broadcast Manager CAN Protocol (with content filtering)"
+	default y
+	help
+	  The Broadcast Manager offers content filtering, timeout monitoring,
+	  sending of RTR frames, and cyclic CAN messages without permanent user
+	  interaction. The BCM can be 'programmed' via the BSD socket API and
+	  informs you on demand e.g. only on content updates / timeouts.
+	  You probably want to use the bcm socket in most cases where cyclic
+	  CAN messages are used on the bus (e.g. in automotive environments).
+	  To use the Broadcast Manager, use AF_CAN with protocol CAN_BCM.
+
+config CAN_GW
+	tristate "CAN Gateway/Router (with netlink configuration)"
+	default y
+	help
+	  The CAN Gateway/Router is used to route (and modify) CAN frames.
+	  It is based on the PF_CAN core infrastructure for msg filtering and
+	  msg sending and can optionally modify routed CAN frames on the fly.
+	  CAN frames can be routed between CAN network interfaces (one hop).
+	  They can be modified with AND/OR/XOR/SET operations as configured
+	  by the netlink configuration interface known e.g. from iptables.
+
+source "net/can/j1939/Kconfig"
+
+config CAN_ISOTP
+	tristate "ISO 15765-2 CAN transport protocol"
+	help
+	  CAN Transport Protocols offer support for segmented Point-to-Point
+	  communication between CAN nodes via two defined CAN Identifiers.
+	  This protocol driver implements segmented data transfers for CAN CC
+	  (aka Classical CAN, CAN 2.0B) and CAN FD frame types which were
+	  introduced with ISO 15765-2:2016.
+	  As CAN frames can only transport a small amount of data bytes
+	  (max. 8 bytes for CAN CC and max. 64 bytes for CAN FD) this
+	  segmentation is needed to transport longer Protocol Data Units (PDU)
+	  as needed e.g. for vehicle diagnosis (UDS, ISO 14229) or IP-over-CAN
+	  traffic.
+
+endif