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, 62 insertions, 0 deletions

diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
new file mode 100644
index 000000000..52899c22d
--- /dev/null
+++ b/drivers/iio/trigger/Kconfig
@@ -0,0 +1,62 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Industrial I/O standalone triggers
+#
+# When adding new entries keep the list in alphabetical order
+
+menu "Triggers - standalone"
+
+config IIO_HRTIMER_TRIGGER
+	tristate "High resolution timer trigger"
+	depends on IIO_SW_TRIGGER
+	help
+	  Provides a frequency based IIO trigger using high resolution
+	  timers as interrupt source.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called iio-trig-hrtimer.
+
+config IIO_STM32_LPTIMER_TRIGGER
+	tristate "STM32 Low-Power Timer Trigger"
+	depends on MFD_STM32_LPTIMER || COMPILE_TEST
+	help
+	  Select this option to enable STM32 Low-Power Timer Trigger.
+	  This can be used as trigger source for STM32 internal ADC
+	  and/or DAC.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called stm32-lptimer-trigger.
+
+config IIO_STM32_TIMER_TRIGGER
+	tristate "STM32 Timer Trigger"
+	depends on (ARCH_STM32 && MFD_STM32_TIMERS) || COMPILE_TEST
+	help
+	  Select this option to enable STM32 Timer Trigger
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called stm32-timer-trigger.
+
+config IIO_TIGHTLOOP_TRIGGER
+	tristate "A kthread based hammering loop trigger"
+	depends on IIO_SW_TRIGGER
+	help
+	  An experimental trigger, used to allow sensors to be sampled as fast
+	  as possible under the limitations of whatever else is going on.
+	  Uses a tight loop in a kthread.  Will only work with lower half only
+	  trigger consumers.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called iio-trig-loop.
+
+config IIO_SYSFS_TRIGGER
+	tristate "SYSFS trigger"
+	depends on SYSFS
+	select IRQ_WORK
+	help
+	  Provides support for using SYSFS entries as IIO triggers.
+	  If unsure, say N (but it's safe to say "Y").
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called iio-trig-sysfs.
+
+endmenu