Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu

Pull the v3.18 RCU changes from Paul E. McKenney:

"
  * Update RCU documentation.  These were posted to LKML at
    https://lkml.org/lkml/2014/8/28/378.

  * Miscellaneous fixes.  These were posted to LKML at
    https://lkml.org/lkml/2014/8/28/386.  An additional fix that
    eliminates a documented (but now inconvenient) deadlock between
    RCU hotplug and expedited grace periods was posted at
    https://lkml.org/lkml/2014/8/28/573.

  * Changes related to No-CBs CPUs and NO_HZ_FULL.  These were posted
    to LKML at https://lkml.org/lkml/2014/8/28/412.

  * Torture-test updates.  These were posted to LKML at
    https://lkml.org/lkml/2014/8/28/546 and at
    https://lkml.org/lkml/2014/9/11/1114.

  * RCU-tasks implementation.  These were posted to LKML at
    https://lkml.org/lkml/2014/8/28/540.
"

Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 13 insertions, 2 deletions

diff --git a/init/Kconfig b/init/Kconfig
index e84c6423a2e5..4fe5500b998f 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -507,6 +507,16 @@ config PREEMPT_RCU
           This option enables preemptible-RCU code that is common between
           TREE_PREEMPT_RCU and, in the old days, TINY_PREEMPT_RCU.
 
+config TASKS_RCU
+        bool "Task_based RCU implementation using voluntary context switch"
+        default n
+        help
+          This option enables a task-based RCU implementation that uses
+          only voluntary context switch (not preemption!), idle, and
+          user-mode execution as quiescent states.
+
+          If unsure, say N.
+
 config RCU_STALL_COMMON
         def_bool ( TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE )
         help
@@ -737,7 +747,7 @@ choice
 
 config RCU_NOCB_CPU_NONE
         bool "No build_forced no-CBs CPUs"
-        depends on RCU_NOCB_CPU && !NO_HZ_FULL_ALL
+        depends on RCU_NOCB_CPU
         help
           This option does not force any of the CPUs to be no-CBs CPUs.
           Only CPUs designated by the rcu_nocbs= boot parameter will be
@@ -751,7 +761,7 @@ config RCU_NOCB_CPU_NONE
 
 config RCU_NOCB_CPU_ZERO
         bool "CPU 0 is a build_forced no-CBs CPU"
-        depends on RCU_NOCB_CPU && !NO_HZ_FULL_ALL
+        depends on RCU_NOCB_CPU
         help
           This option forces CPU 0 to be a no-CBs CPU, so that its RCU
           callbacks are invoked by a per-CPU kthread whose name begins
diff --git a/init/main.c b/init/main.c
index bb1aed928f21..e3c4cdd94d5b 100644
--- a/init/main.c
+++ b/init/main.c
@@ -578,6 +578,7 @@ asmlinkage __visible void __init start_kernel(void)
         idr_init_cache();
         rcu_init();
         tick_nohz_init();
+        rcu_init_nohz();
         context_tracking_init();
         radix_tree_init();
         /* init some links before init_ISA_irqs() */