2 files changed, 21 insertions, 36 deletions

diff --git a/init/Kconfig b/init/Kconfig
index 3f7e60995c80..8e8b76d8a272 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -316,38 +316,28 @@ choice
         prompt "RCU Implementation"
         default TREE_RCU
 
-config CLASSIC_RCU
-        bool "Classic RCU"
-        help
-          This option selects the classic RCU implementation that is
-          designed for best read-side performance on non-realtime
-          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.
+          thousands of CPUs.  It also scales down nicely to
+          smaller systems.
 
-config PREEMPT_RCU
-        bool "Preemptible RCU"
+config TREE_PREEMPT_RCU
+        bool "Preemptable tree-based hierarchical 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.
+          This option selects the RCU implementation that is
+          designed for very large SMP systems with hundreds or
+          thousands of CPUs, but for which real-time response
+          is also required.
 
 endchoice
 
 config RCU_TRACE
         bool "Enable tracing for RCU"
-        depends on TREE_RCU || PREEMPT_RCU
+        depends on TREE_RCU || TREE_PREEMPT_RCU
         help
           This option provides tracing in RCU which presents stats
           in debugfs for debugging RCU implementation.
@@ -359,7 +349,7 @@ config RCU_FANOUT
         int "Tree-based hierarchical RCU fanout value"
         range 2 64 if 64BIT
         range 2 32 if !64BIT
-        depends on TREE_RCU
+        depends on TREE_RCU || TREE_PREEMPT_RCU
         default 64 if 64BIT
         default 32 if !64BIT
         help
@@ -374,7 +364,7 @@ config RCU_FANOUT
 
 config RCU_FANOUT_EXACT
         bool "Disable tree-based hierarchical RCU auto-balancing"
-        depends on TREE_RCU
+        depends on TREE_RCU || TREE_PREEMPT_RCU
         default n
         help
           This option forces use of the exact RCU_FANOUT value specified,
@@ -387,18 +377,12 @@ config RCU_FANOUT_EXACT
           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
+        def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
         select DEBUG_FS
         help
-          This option provides tracing for the PREEMPT_RCU implementation,
-          permitting Makefile to trivially select kernel/rcupreempt_trace.c.
+          This option provides tracing for the TREE_RCU and
+          TREE_PREEMPT_RCU implementations, permitting Makefile to
+          trivially select kernel/rcutree_trace.c.
 
 endmenu # "RCU Subsystem"
 
diff --git a/init/main.c b/init/main.c
index 2f9544d8435a..63904bb6ae37 100644
--- a/init/main.c
+++ b/init/main.c
@@ -427,6 +427,7 @@ static noinline void __init_refok rest_init(void)
 {
         int pid;
 
+        rcu_scheduler_starting();
         kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
         numa_default_policy();
         pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
@@ -438,7 +439,6 @@ static noinline void __init_refok rest_init(void)
          * at least once to get things moving:
          */
         init_idle_bootup_task(current);
-        rcu_scheduler_starting();
         preempt_enable_no_resched();
         schedule();
         preempt_disable();
@@ -607,7 +607,6 @@ asmlinkage void __init start_kernel(void)
         softirq_init();
         timekeeping_init();
         time_init();
-        sched_clock_init();
         profile_init();
         if (!irqs_disabled())
                 printk(KERN_CRIT "start_kernel(): bug: interrupts were "
@@ -658,6 +657,7 @@ asmlinkage void __init start_kernel(void)
         numa_policy_init();
         if (late_time_init)
                 late_time_init();
+        sched_clock_init();
         calibrate_delay();
         pidmap_init();
         anon_vma_init();
@@ -709,13 +709,14 @@ static void __init do_ctors(void)
 int initcall_debug;
 core_param(initcall_debug, initcall_debug, bool, 0644);
 
+static char msgbuf[64];
+static struct boot_trace_call call;
+static struct boot_trace_ret ret;
+
 int do_one_initcall(initcall_t fn)
 {
         int count = preempt_count();
         ktime_t calltime, delta, rettime;
-        char msgbuf[64];
-        struct boot_trace_call call;
-        struct boot_trace_ret ret;
 
         if (initcall_debug) {
                 call.caller = task_pid_nr(current);