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, 26 insertions, 0 deletions

diff --git a/drivers/misc/keba/Kconfig b/drivers/misc/keba/Kconfig
new file mode 100644
index 000000000..d6d47197a
--- /dev/null
+++ b/drivers/misc/keba/Kconfig
@@ -0,0 +1,26 @@
+# SPDX-License-Identifier: GPL-2.0
+config KEBA_CP500
+	tristate "KEBA CP500 system FPGA support"
+	depends on X86_64 || ARM64 || COMPILE_TEST
+	depends on PCI
+	depends on I2C
+	select AUXILIARY_BUS
+	help
+	  This driver supports the KEBA CP500 system FPGA, which is used in
+	  KEBA CP500 devices. It registers all sub devices present on the CP500
+	  system FPGA as separate devices. A driver is needed for each sub
+	  device.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called cp500.
+
+config KEBA_LAN9252
+	tristate "KEBA CP500 LAN9252 configuration"
+	depends on SPI
+	depends on KEBA_CP500 || COMPILE_TEST
+	help
+	  This driver is used for updating the configuration of the LAN9252
+	  controller on KEBA CP500 devices.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called lan9252.