Merge branch 'tracing/kmemtrace' into tracing/kmemtrace2

init/Kconfig

@@ -936,10 +936,90 @@ source "block/Kconfig"
 config PREEMPT_NOTIFIERS
 	bool
 
+choice
+	prompt "RCU Implementation"
+	default CLASSIC_RCU
+
 config CLASSIC_RCU
-	def_bool !PREEMPT_RCU
+	bool "Classic RCU"
 	help
 	  This option selects the classic RCU implementation that is
 	  designed for best read-side performance on non-realtime
-	  systems.  Classic RCU is the default.  Note that the
-	  PREEMPT_RCU symbol is used to select/deselect this option.
+	  systems.
+
+	  Select this option if you are unsure.
+
+config TREE_RCU
+	bool "Tree-based hierarchical RCU"
+	help
+	  This option selects the RCU implementation that is
+	  designed for very large SMP system with hundreds or
+	  thousands of CPUs.
+
+config PREEMPT_RCU
+	bool "Preemptible RCU"
+	depends on PREEMPT
+	help
+	  This option reduces the latency of the kernel by making certain
+	  RCU sections preemptible. Normally RCU code is non-preemptible, if
+	  this option is selected then read-only RCU sections become
+	  preemptible. This helps latency, but may expose bugs due to
+	  now-naive assumptions about each RCU read-side critical section
+	  remaining on a given CPU through its execution.
+
+endchoice
+
+config RCU_TRACE
+	bool "Enable tracing for RCU"
+	depends on TREE_RCU || PREEMPT_RCU
+	help
+	  This option provides tracing in RCU which presents stats
+	  in debugfs for debugging RCU implementation.
+
+	  Say Y here if you want to enable RCU tracing
+	  Say N if you are unsure.
+
+config RCU_FANOUT
+	int "Tree-based hierarchical RCU fanout value"
+	range 2 64 if 64BIT
+	range 2 32 if !64BIT
+	depends on TREE_RCU
+	default 64 if 64BIT
+	default 32 if !64BIT
+	help
+	  This option controls the fanout of hierarchical implementations
+	  of RCU, allowing RCU to work efficiently on machines with
+	  large numbers of CPUs.  This value must be at least the cube
+	  root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
+	  systems and up to 262,144 for 64-bit systems.
+
+	  Select a specific number if testing RCU itself.
+	  Take the default if unsure.
+
+config RCU_FANOUT_EXACT
+	bool "Disable tree-based hierarchical RCU auto-balancing"
+	depends on TREE_RCU
+	default n
+	help
+	  This option forces use of the exact RCU_FANOUT value specified,
+	  regardless of imbalances in the hierarchy.  This is useful for
+	  testing RCU itself, and might one day be useful on systems with
+	  strong NUMA behavior.
+
+	  Without RCU_FANOUT_EXACT, the code will balance the hierarchy.
+
+	  Say N if unsure.
+
+config TREE_RCU_TRACE
+	def_bool RCU_TRACE && TREE_RCU
+	select DEBUG_FS
+	help
+	  This option provides tracing for the TREE_RCU implementation,
+	  permitting Makefile to trivially select kernel/rcutree_trace.c.
+
+config PREEMPT_RCU_TRACE
+	def_bool RCU_TRACE && PREEMPT_RCU
+	select DEBUG_FS
+	help
+	  This option provides tracing for the PREEMPT_RCU implementation,
+	  permitting Makefile to trivially select kernel/rcupreempt_trace.c.

init/main.c

@@ -541,6 +541,15 @@ void __init __weak thread_info_cache_init(void)
 {
 }
 
+void __init __weak arch_early_irq_init(void)
+{
+}
+
+void __init __weak early_irq_init(void)
+{
+	arch_early_irq_init();
+}
+
 asmlinkage void __init start_kernel(void)
 {
 	char * command_line;
@@ -605,6 +614,8 @@ asmlinkage void __init start_kernel(void)
 	sort_main_extable();
 	trap_init();
 	rcu_init();
+	/* init some links before init_ISA_irqs() */
+	early_irq_init();
 	init_IRQ();
 	pidhash_init();
 	init_timers();