rcu: Move RCU debug Kconfig options to kernel/rcu

RCU's debugging Kconfig options are in the unintuitive location
lib/Kconfig.debug, and there are enough of them that it would be good for
them to be more centralized.  This commit therefore extracts RCU's Kconfig
options from init/Kconfig into a new kernel/rcu/Kconfig.debug file.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

kernel/rcu/Kconfig.debug

+#
+# RCU-related debugging configuration options
+#
+
+menu "RCU Debugging"
+
+config PROVE_RCU
+	def_bool PROVE_LOCKING
+
+config TORTURE_TEST
+	tristate
+	default n
+
+config RCU_PERF_TEST
+	tristate "performance tests for RCU"
+	depends on DEBUG_KERNEL
+	select TORTURE_TEST
+	select SRCU
+	select TASKS_RCU
+	default n
+	help
+	  This option provides a kernel module that runs performance
+	  tests on the RCU infrastructure.  The kernel module may be built
+	  after the fact on the running kernel to be tested, if desired.
+
+	  Say Y here if you want RCU performance tests to be built into
+	  the kernel.
+	  Say M if you want the RCU performance tests to build as a module.
+	  Say N if you are unsure.
+
+config RCU_TORTURE_TEST
+	tristate "torture tests for RCU"
+	depends on DEBUG_KERNEL
+	select TORTURE_TEST
+	select SRCU
+	select TASKS_RCU
+	default n
+	help
+	  This option provides a kernel module that runs torture tests
+	  on the RCU infrastructure.  The kernel module may be built
+	  after the fact on the running kernel to be tested, if desired.
+
+	  Say Y here if you want RCU torture tests to be built into
+	  the kernel.
+	  Say M if you want the RCU torture tests to build as a module.
+	  Say N if you are unsure.
+
+config RCU_CPU_STALL_TIMEOUT
+	int "RCU CPU stall timeout in seconds"
+	depends on RCU_STALL_COMMON
+	range 3 300
+	default 21
+	help
+	  If a given RCU grace period extends more than the specified
+	  number of seconds, a CPU stall warning is printed.  If the
+	  RCU grace period persists, additional CPU stall warnings are
+	  printed at more widely spaced intervals.
+
+config RCU_TRACE
+	bool "Enable tracing for RCU"
+	depends on DEBUG_KERNEL
+	default y if TREE_RCU
+	select TRACE_CLOCK
+	help
+	  This option enables additional tracepoints for ftrace-style
+	  event tracing.
+
+	  Say Y here if you want to enable RCU tracing
+	  Say N if you are unsure.
+
+config RCU_EQS_DEBUG
+	bool "Provide debugging asserts for adding NO_HZ support to an arch"
+	depends on DEBUG_KERNEL
+	help
+	  This option provides consistency checks in RCU's handling of
+	  NO_HZ.  These checks have proven quite helpful in detecting
+	  bugs in arch-specific NO_HZ code.
+
+	  Say N here if you need ultimate kernel/user switch latencies
+	  Say Y if you are unsure
+
+endmenu # "RCU Debugging"

lib/Kconfig.debug

@@ -1301,84 +1301,7 @@ config DEBUG_CREDENTIALS
 
 	  If unsure, say N.
 
-menu "RCU Debugging"
-
-config PROVE_RCU
-	def_bool PROVE_LOCKING
-
-config TORTURE_TEST
-	tristate
-	default n
-
-config RCU_PERF_TEST
-	tristate "performance tests for RCU"
-	depends on DEBUG_KERNEL
-	select TORTURE_TEST
-	select SRCU
-	select TASKS_RCU
-	default n
-	help
-	  This option provides a kernel module that runs performance
-	  tests on the RCU infrastructure.  The kernel module may be built
-	  after the fact on the running kernel to be tested, if desired.
-
-	  Say Y here if you want RCU performance tests to be built into
-	  the kernel.
-	  Say M if you want the RCU performance tests to build as a module.
-	  Say N if you are unsure.
-
-config RCU_TORTURE_TEST
-	tristate "torture tests for RCU"
-	depends on DEBUG_KERNEL
-	select TORTURE_TEST
-	select SRCU
-	select TASKS_RCU
-	default n
-	help
-	  This option provides a kernel module that runs torture tests
-	  on the RCU infrastructure.  The kernel module may be built
-	  after the fact on the running kernel to be tested, if desired.
-
-	  Say Y here if you want RCU torture tests to be built into
-	  the kernel.
-	  Say M if you want the RCU torture tests to build as a module.
-	  Say N if you are unsure.
-
-config RCU_CPU_STALL_TIMEOUT
-	int "RCU CPU stall timeout in seconds"
-	depends on RCU_STALL_COMMON
-	range 3 300
-	default 21
-	help
-	  If a given RCU grace period extends more than the specified
-	  number of seconds, a CPU stall warning is printed.  If the
-	  RCU grace period persists, additional CPU stall warnings are
-	  printed at more widely spaced intervals.
-
-config RCU_TRACE
-	bool "Enable tracing for RCU"
-	depends on DEBUG_KERNEL
-	default y if TREE_RCU
-	select TRACE_CLOCK
-	help
-	  This option enables additional tracepoints for ftrace-style
-	  event tracing.
-
-	  Say Y here if you want to enable RCU tracing
-	  Say N if you are unsure.
-
-config RCU_EQS_DEBUG
-	bool "Provide debugging asserts for adding NO_HZ support to an arch"
-	depends on DEBUG_KERNEL
-	help
-	  This option provides consistency checks in RCU's handling of
-	  NO_HZ.  These checks have proven quite helpful in detecting
-	  bugs in arch-specific NO_HZ code.
-
-	  Say N here if you need ultimate kernel/user switch latencies
-	  Say Y if you are unsure
-
-endmenu # "RCU Debugging"
+source "kernel/rcu/Kconfig.debug"
 
 config DEBUG_WQ_FORCE_RR_CPU
 	bool "Force round-robin CPU selection for unbound work items"