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.

Major changes:

" 1.	Update RCU documentation.  These were posted to LKML at
	http://article.gmane.org/gmane.linux.kernel/1566994.

  2.	Miscellaneous fixes.  These were posted to LKML at
	http://article.gmane.org/gmane.linux.kernel/1567027.

  3.	Grace-period-related changes, primarily to aid in debugging,
	inspired by a -rt debugging session.  These were posted to
	LKML at http://article.gmane.org/gmane.linux.kernel/1567076.

  4.	Idle entry/exit changes, primarily to address issues located
	by Tibor Billes.  These were posted to LKML at
	http://article.gmane.org/gmane.linux.kernel/1567096.

  5.	Code reorganization moving RCU's source files from kernel
	to kernel/rcu.  This was posted to LKML at
	http://article.gmane.org/gmane.linux.kernel/1577344."

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

24 files changed, 464 insertions, 190 deletions

diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl
index fe397f90a34f..6c9d9d37c83a 100644
--- a/Documentation/DocBook/device-drivers.tmpl
+++ b/Documentation/DocBook/device-drivers.tmpl
@@ -87,7 +87,10 @@ X!Iinclude/linux/kobject.h
 !Ekernel/printk/printk.c
 !Ekernel/panic.c
 !Ekernel/sys.c
-!Ekernel/rcupdate.c
+!Ekernel/rcu/srcu.c
+!Ekernel/rcu/tree.c
+!Ekernel/rcu/tree_plugin.h
+!Ekernel/rcu/update.c
      </sect1>
 
      <sect1><title>Device Resource Management</title>
diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt
index 7703ec73a9bb..91266193b8f4 100644
--- a/Documentation/RCU/checklist.txt
+++ b/Documentation/RCU/checklist.txt
@@ -202,8 +202,8 @@ over a rather long period of time, but improvements are always welcome!
         updater uses call_rcu_sched() or synchronize_sched(), then
         the corresponding readers must disable preemption, possibly
         by calling rcu_read_lock_sched() and rcu_read_unlock_sched().
-        If the updater uses synchronize_srcu() or call_srcu(),
-        the the corresponding readers must use srcu_read_lock() and
+        If the updater uses synchronize_srcu() or call_srcu(), then
+        the corresponding readers must use srcu_read_lock() and
         srcu_read_unlock(), and with the same srcu_struct.  The rules for
         the expedited primitives are the same as for their non-expedited
         counterparts.  Mixing things up will result in confusion and
diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt
index 8e9359de1d28..6f3a0057548e 100644
--- a/Documentation/RCU/stallwarn.txt
+++ b/Documentation/RCU/stallwarn.txt
@@ -12,12 +12,12 @@ CONFIG_RCU_CPU_STALL_TIMEOUT
         This kernel configuration parameter defines the period of time
         that RCU will wait from the beginning of a grace period until it
         issues an RCU CPU stall warning.  This time period is normally
-        sixty seconds.
+        21 seconds.
 
         This configuration parameter may be changed at runtime via the
         /sys/module/rcutree/parameters/rcu_cpu_stall_timeout, however
         this parameter is checked only at the beginning of a cycle.
-        So if you are 30 seconds into a 70-second stall, setting this
+        So if you are 10 seconds into a 40-second stall, setting this
         sysfs parameter to (say) five will shorten the timeout for the
         -next- stall, or the following warning for the current stall
         (assuming the stall lasts long enough).  It will not affect the
@@ -32,7 +32,7 @@ CONFIG_RCU_CPU_STALL_VERBOSE
         also dump the stacks of any tasks that are blocking the current
         RCU-preempt grace period.
 
-RCU_CPU_STALL_INFO
+CONFIG_RCU_CPU_STALL_INFO
 
         This kernel configuration parameter causes the stall warning to
         print out additional per-CPU diagnostic information, including
@@ -43,7 +43,8 @@ RCU_STALL_DELAY_DELTA
         Although the lockdep facility is extremely useful, it does add
         some overhead.  Therefore, under CONFIG_PROVE_RCU, the
         RCU_STALL_DELAY_DELTA macro allows five extra seconds before
-        giving an RCU CPU stall warning message.
+        giving an RCU CPU stall warning message.  (This is a cpp
+        macro, not a kernel configuration parameter.)
 
 RCU_STALL_RAT_DELAY
 
@@ -52,7 +53,8 @@ RCU_STALL_RAT_DELAY
         However, if the offending CPU does not detect its own stall in
         the number of jiffies specified by RCU_STALL_RAT_DELAY, then
         some other CPU will complain.  This delay is normally set to
-        two jiffies.
+        two jiffies.  (This is a cpp macro, not a kernel configuration
+        parameter.)
 
 When a CPU detects that it is stalling, it will print a message similar
 to the following:
@@ -86,7 +88,12 @@ printing, there will be a spurious stall-warning message:
 
 INFO: rcu_bh_state detected stalls on CPUs/tasks: { } (detected by 4, 2502 jiffies)
 
-This is rare, but does happen from time to time in real life.
+This is rare, but does happen from time to time in real life.  It is also
+possible for a zero-jiffy stall to be flagged in this case, depending
+on how the stall warning and the grace-period initialization happen to
+interact.  Please note that it is not possible to entirely eliminate this
+sort of false positive without resorting to things like stop_machine(),
+which is overkill for this sort of problem.
 
 If the CONFIG_RCU_CPU_STALL_INFO kernel configuration parameter is set,
 more information is printed with the stall-warning message, for example:
@@ -216,4 +223,5 @@ that portion of the stack which remains the same from trace to trace.
 If you can reliably trigger the stall, ftrace can be quite helpful.
 
 RCU bugs can often be debugged with the help of CONFIG_RCU_TRACE
-and with RCU's event tracing.
+and with RCU's event tracing.  For information on RCU's event tracing,
+see include/trace/events/rcu.h.
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index fcbb736d55fe..203f4a9d9efe 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2599,7 +2599,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
         ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
                         See Documentation/blockdev/ramdisk.txt.
 
-        rcu_nocbs=      [KNL,BOOT]
+        rcu_nocbs=      [KNL]
                         In kernels built with CONFIG_RCU_NOCB_CPU=y, set
                         the specified list of CPUs to be no-callback CPUs.
                         Invocation of these CPUs' RCU callbacks will
@@ -2612,7 +2612,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         real-time workloads.  It can also improve energy
                         efficiency for asymmetric multiprocessors.
 
-        rcu_nocb_poll   [KNL,BOOT]
+        rcu_nocb_poll   [KNL]
                         Rather than requiring that offloaded CPUs
                         (specified by rcu_nocbs= above) explicitly
                         awaken the corresponding "rcuoN" kthreads,
@@ -2623,126 +2623,145 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         energy efficiency by requiring that the kthreads
                         periodically wake up to do the polling.
 
-        rcutree.blimit= [KNL,BOOT]
+        rcutree.blimit= [KNL]
                         Set maximum number of finished RCU callbacks to process
                         in one batch.
 
-        rcutree.fanout_leaf=    [KNL,BOOT]
+        rcutree.rcu_fanout_leaf= [KNL]
                         Increase the number of CPUs assigned to each