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, 93 insertions, 0 deletions

diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
new file mode 100644
index 000000000..00e256204
--- /dev/null
+++ b/drivers/cpuidle/Kconfig
@@ -0,0 +1,93 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menu "CPU Idle"
+
+config CPU_IDLE
+	bool "CPU idle PM support"
+	default y if ACPI || PPC_PSERIES
+	select CPU_IDLE_GOV_LADDER if (!NO_HZ && !NO_HZ_IDLE)
+	select CPU_IDLE_GOV_MENU if (NO_HZ || NO_HZ_IDLE) && !CPU_IDLE_GOV_TEO
+	help
+	  CPU idle is a generic framework for supporting software-controlled
+	  idle processor power management.  It includes modular cross-platform
+	  governors that can be swapped during runtime.
+
+	  If you're using an ACPI-enabled platform, you should say Y here.
+
+if CPU_IDLE
+
+config CPU_IDLE_MULTIPLE_DRIVERS
+	bool
+
+config CPU_IDLE_GOV_LADDER
+	bool "Ladder governor (for periodic timer tick)"
+
+config CPU_IDLE_GOV_MENU
+	bool "Menu governor (for tickless system)"
+
+config CPU_IDLE_GOV_TEO
+	bool "Timer events oriented (TEO) governor (for tickless systems)"
+	help
+	  This governor implements a simplified idle state selection method
+	  focused on timer events and does not do any interactivity boosting.
+
+	  Some workloads benefit from using it and it generally should be safe
+	  to use.  Say Y here if you are not happy with the alternatives.
+
+config CPU_IDLE_GOV_HALTPOLL
+	bool "Haltpoll governor (for virtualized systems)"
+	depends on KVM_GUEST
+	help
+	  This governor implements haltpoll idle state selection, to be
+	  used in conjunction with the haltpoll cpuidle driver, allowing
+	  for polling for a certain amount of time before entering idle
+	  state.
+
+	  Some virtualized workloads benefit from using it.
+
+config DT_IDLE_STATES
+	bool
+
+config DT_IDLE_GENPD
+	depends on PM_GENERIC_DOMAINS_OF
+	bool
+
+menu "ARM CPU Idle Drivers"
+depends on ARM || ARM64
+source "drivers/cpuidle/Kconfig.arm"
+endmenu
+
+menu "MIPS CPU Idle Drivers"
+depends on MIPS
+source "drivers/cpuidle/Kconfig.mips"
+endmenu
+
+menu "POWERPC CPU Idle Drivers"
+depends on PPC
+source "drivers/cpuidle/Kconfig.powerpc"
+endmenu
+
+menu "RISC-V CPU Idle Drivers"
+depends on RISCV
+source "drivers/cpuidle/Kconfig.riscv"
+endmenu
+
+menu "S390 CPU Idle Drivers"
+depends on S390
+source "drivers/cpuidle/Kconfig.s390"
+endmenu
+
+config HALTPOLL_CPUIDLE
+	tristate "Halt poll cpuidle driver"
+	depends on X86 && KVM_GUEST
+	select CPU_IDLE_GOV_HALTPOLL
+	default y
+	help
+	 This option enables halt poll cpuidle driver, which allows to poll
+	 before halting in the guest (more efficient than polling in the
+	 host via halt_poll_ns for some scenarios).
+
+endif # CPU_IDLE
+
+config ARCH_NEEDS_CPU_IDLE_COUPLED
+	def_bool n
+endmenu