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, 44 insertions, 0 deletions

diff --git a/drivers/iio/resolver/Kconfig b/drivers/iio/resolver/Kconfig
new file mode 100644
index 000000000..de2dee383
--- /dev/null
+++ b/drivers/iio/resolver/Kconfig
@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Resolver/Synchro drivers
+#
+menu "Resolver to digital converters"
+
+config AD2S90
+	tristate "Analog Devices ad2s90 driver"
+	depends on SPI
+	help
+	  Say yes here to build support for Analog Devices spi resolver
+	  to digital converters, ad2s90, provides direct access via sysfs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad2s90.
+
+config AD2S1200
+	tristate "Analog Devices ad2s1200/ad2s1205 driver"
+	depends on SPI
+	depends on GPIOLIB || COMPILE_TEST
+	help
+	  Say yes here to build support for Analog Devices spi resolver
+	  to digital converters, ad2s1200 and ad2s1205, provides direct access
+	  via sysfs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad2s1200.
+
+config AD2S1210
+	tristate "Analog Devices ad2s1210 driver"
+	depends on SPI
+	depends on COMMON_CLK
+	depends on GPIOLIB || COMPILE_TEST
+	select REGMAP
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for Analog Devices spi resolver
+	  to digital converters, ad2s1210, provides direct access via sysfs.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad2s1210.
+
+endmenu