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

Pull RCU updates from Paul E. McKenney:

 - Streamline RCU's use of per-CPU variables, shifting from "cpu"
   arguments to functions to "this_"-style per-CPU variable accessors.

 - Signal-handling RCU updates.

 - Real-time updates.

 - Torture-test updates.

 - Miscellaneous fixes.

 - Documentation updates.

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

1 files changed, 21 insertions, 28 deletions

diff --git a/init/Kconfig b/init/Kconfig
index 2081a4d3d917..903505e66d1d 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -477,7 +477,7 @@ config TREE_RCU
 	  thousands of CPUs.  It also scales down nicely to
 	  smaller systems.
 
-config TREE_PREEMPT_RCU
+config PREEMPT_RCU
 	bool "Preemptible tree-based hierarchical RCU"
 	depends on PREEMPT
 	select IRQ_WORK
@@ -501,12 +501,6 @@ config TINY_RCU
 
 endchoice
 
-config PREEMPT_RCU
-	def_bool TREE_PREEMPT_RCU
-	help
-	  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
@@ -518,7 +512,7 @@ config TASKS_RCU
 	  If unsure, say N.
 
 config RCU_STALL_COMMON
-	def_bool ( TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE )
+	def_bool ( TREE_RCU || PREEMPT_RCU || RCU_TRACE )
 	help
 	  This option enables RCU CPU stall code that is common between
 	  the TINY and TREE variants of RCU.  The purpose is to allow
@@ -576,7 +570,7 @@ config RCU_FANOUT
 	int "Tree-based hierarchical RCU fanout value"
 	range 2 64 if 64BIT
 	range 2 32 if !64BIT
-	depends on TREE_RCU || TREE_PREEMPT_RCU
+	depends on TREE_RCU || PREEMPT_RCU
 	default 64 if 64BIT
 	default 32 if !64BIT
 	help
@@ -596,7 +590,7 @@ config RCU_FANOUT_LEAF
 	int "Tree-based hierarchical RCU leaf-level fanout value"
 	range 2 RCU_FANOUT if 64BIT
 	range 2 RCU_FANOUT if !64BIT
-	depends on TREE_RCU || TREE_PREEMPT_RCU
+	depends on TREE_RCU || PREEMPT_RCU
 	default 16
 	help
 	  This option controls the leaf-level fanout of hierarchical
@@ -621,7 +615,7 @@ config RCU_FANOUT_LEAF
 
 config RCU_FANOUT_EXACT
 	bool "Disable tree-based hierarchical RCU auto-balancing"
-	depends on TREE_RCU || TREE_PREEMPT_RCU
+	depends on TREE_RCU || PREEMPT_RCU
 	default n
 	help
 	  This option forces use of the exact RCU_FANOUT value specified,
@@ -652,11 +646,11 @@ config RCU_FAST_NO_HZ
 	  Say N if you are unsure.
 
 config TREE_RCU_TRACE
-	def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
+	def_bool RCU_TRACE && ( TREE_RCU || PREEMPT_RCU )
 	select DEBUG_FS
 	help
 	  This option provides tracing for the TREE_RCU and
-	  TREE_PREEMPT_RCU implementations, permitting Makefile to
+	  PREEMPT_RCU implementations, permitting Makefile to
 	  trivially select kernel/rcutree_trace.c.
 
 config RCU_BOOST
@@ -672,30 +666,31 @@ config RCU_BOOST
 	  Say Y here if you are working with real-time apps or heavy loads
 	  Say N here if you are unsure.
 
-config RCU_BOOST_PRIO
-	int "Real-time priority to boost RCU readers to"
+config RCU_KTHREAD_PRIO
+	int "Real-time priority to use for RCU worker threads"
 	range 1 99
 	depends on RCU_BOOST
 	default 1
 	help
-	  This option specifies the real-time priority to which long-term
-	  preempted RCU readers are to be boosted.  If you are working
-	  with a real-time application that has one or more CPU-bound
-	  threads running at a real-time priority level, you should set
-	  RCU_BOOST_PRIO to a priority higher then the highest-priority
-	  real-time CPU-bound thread.  The default RCU_BOOST_PRIO value
-	  of 1 is appropriate in the common case, which is real-time
+	  This option specifies the SCHED_FIFO priority value that will be
+	  assigned to the rcuc/n and rcub/n threads and is also the value
+	  used for RCU_BOOST (if enabled). If you are working with a
+	  real-time application that has one or more CPU-bound threads
+	  running at a real-time priority level, you should set
+	  RCU_KTHREAD_PRIO to a priority higher than the highest-priority
+	  real-time CPU-bound application thread.  The default RCU_KTHREAD_PRIO
+	  value of 1 is appropriate in the common case, which is real-time
 	  applications that do not have any CPU-bound threads.
 
 	  Some real-time applications might not have a single real-time
 	  thread that saturates a given CPU, but instead might have
 	  multiple real-time threads that, taken together, fully utilize
-	  that CPU.  In this case, you should set RCU_BOOST_PRIO to
+	  that CPU.  In this case, you should set RCU_KTHREAD_PRIO to
 	  a priority higher than the lowest-priority thread that is
 	  conspiring to prevent the CPU from running any non-real-time
 	  tasks.  For example, if one thread at priority 10 and another
 	  thread at priority 5 are between themselves fully consuming
-	  the CPU time on a given CPU, then RCU_BOOST_PRIO should be
+	  the CPU time on a given CPU, then RCU_KTHREAD_PRIO should be
 	  set to priority 6 or higher.
 
 	  Specify the real-time priority, or take the default if unsure.
@@ -715,7 +710,7 @@ config RCU_BOOST_DELAY
 
 config RCU_NOCB_CPU
 	bool "Offload RCU callback processing from boot-selected CPUs"
-	depends on TREE_RCU || TREE_PREEMPT_RCU
+	depends on TREE_RCU || PREEMPT_RCU
 	default n
 	help
 	  Use this option to reduce OS jitter for aggressive HPC or
@@ -739,6 +734,7 @@ config RCU_NOCB_CPU
 choice
 	prompt "Build-forced no-CBs CPUs"
 	default RCU_NOCB_CPU_NONE
+	depends on RCU_NOCB_CPU
 	help
 	  This option allows no-CBs CPUs (whose RCU callbacks are invoked
 	  from kthreads rather than from softirq context) to be specified
@@ -747,7 +743,6 @@ choice
 
 config RCU_NOCB_CPU_NONE
 	bool "No build_forced no-CBs CPUs"
-	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
@@ -761,7 +756,6 @@ 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
 	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
@@ -776,7 +770,6 @@ config RCU_NOCB_CPU_ZERO
 
 config RCU_NOCB_CPU_ALL
 	bool "All CPUs are build_forced no-CBs CPUs"
-	depends on RCU_NOCB_CPU
 	help
 	  This option forces all CPUs to be no-CBs CPUs.  The rcu_nocbs=
 	  boot parameter will be ignored.  All CPUs' RCU callbacks will