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