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

Pull the v3.5 RCU tree from Paul E. McKenney:

 1)	A set of improvements and fixes to the RCU_FAST_NO_HZ feature
	(with more on the way for 3.6).  Posted to LKML:
	https://lkml.org/lkml/2012/4/23/324 (commits 1-3 and 5),
	https://lkml.org/lkml/2012/4/16/611 (commit 4),
	https://lkml.org/lkml/2012/4/30/390 (commit 6), and
	https://lkml.org/lkml/2012/5/4/410 (commit 7, combined with
	the other commits for the convenience of the tester).

 2)	Changes to make rcu_barrier() avoid disrupting execution of CPUs
	that have no RCU callbacks.  Posted to LKML:
	https://lkml.org/lkml/2012/4/23/322.

 3)	A couple of commits that improve the efficiency of the interaction
	between preemptible RCU and the scheduler, these two being all
	that survived an abortive attempt to allow preemptible RCU's
	__rcu_read_lock() to be inlined.  The full set was posted to
	LKML at https://lkml.org/lkml/2012/4/14/143, and the first and
	third patches of that set remain.

 4)	Lai Jiangshan's algorithmic implementation of SRCU, which includes
	call_srcu() and srcu_barrier().  A major feature of this new
	implementation is that synchronize_srcu() no longer disturbs
	the execution of other CPUs.  This work is based on earlier
	implementations by Peter Zijlstra and Paul E. McKenney.  Posted to
	LKML: https://lkml.org/lkml/2012/2/22/82.

 5)	A number of miscellaneous bug fixes and improvements which were
	posted to LKML at: https://lkml.org/lkml/2012/4/23/353 with
	subsequent updates posted to LKML.

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

23 files changed, 1358 insertions, 353 deletions

diff --git a/Documentation/RCU/torture.txt b/Documentation/RCU/torture.txt
index 375d3fb71437..4ddf3913fd8c 100644
--- a/Documentation/RCU/torture.txt
+++ b/Documentation/RCU/torture.txt
@@ -47,6 +47,16 @@ irqreader	Says to invoke RCU readers from irq level.  This is currently
                 permit this.  (Or, more accurately, variants of RCU that do
                 -not- permit this know to ignore this variable.)
 
+n_barrier_cbs   If this is nonzero, RCU barrier testing will be conducted,
+                in which case n_barrier_cbs specifies the number of
+                RCU callbacks (and corresponding kthreads) to use for
+                this testing.  The value cannot be negative.  If you
+                specify this to be non-zero when torture_type indicates a
+                synchronous RCU implementation (one for which a member of
+                the synchronize_rcu() rather than the call_rcu() family is
+                used -- see the documentation for torture_type below), an
+                error will be reported and no testing will be carried out.
+
 nfakewriters    This is the number of RCU fake writer threads to run.  Fake
                 writer threads repeatedly use the synchronous "wait for
                 current readers" function of the interface selected by
@@ -188,7 +198,7 @@ OUTPUT
 The statistics output is as follows:
 
         rcu-torture:--- Start of test: nreaders=16 nfakewriters=4 stat_interval=30 verbose=0 test_no_idle_hz=1 shuffle_interval=3 stutter=5 irqreader=1 fqs_duration=0 fqs_holdoff=0 fqs_stutter=3 test_boost=1/0 test_boost_interval=7 test_boost_duration=4
-        rcu-torture: rtc:           (null) ver: 155441 tfle: 0 rta: 155441 rtaf: 8884 rtf: 155440 rtmbe: 0 rtbke: 0 rtbre: 0 rtbf: 0 rtb: 0 nt: 3055767
+        rcu-torture: rtc:           (null) ver: 155441 tfle: 0 rta: 155441 rtaf: 8884 rtf: 155440 rtmbe: 0 rtbe: 0 rtbke: 0 rtbre: 0 rtbf: 0 rtb: 0 nt: 3055767
         rcu-torture: Reader Pipe:  727860534 34213 0 0 0 0 0 0 0 0 0
         rcu-torture: Reader Batch:  727877838 17003 0 0 0 0 0 0 0 0 0
         rcu-torture: Free-Block Circulation:  155440 155440 155440 155440 155440 155440 155440 155440 155440 155440 0
@@ -230,6 +240,9 @@ o	"rtmbe": A non-zero value indicates that rcutorture believes that
         rcu_assign_pointer() and rcu_dereference() are not working
         correctly.  This value should be zero.
 
+o       "rtbe": A non-zero value indicates that one of the rcu_barrier()
+        family of functions is not working correctly.
+
 o       "rtbke": rcutorture was unable to create the real-time kthreads
         used to force RCU priority inversion.  This value should be zero.
 
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index c1601e5a8b71..ab84a01c8d68 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2330,18 +2330,100 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
         ramdisk_size=   [RAM] Sizes of RAM disks in kilobytes
                         See Documentation/blockdev/ramdisk.txt.
 
-        rcupdate.blimit=        [KNL,BOOT]
+        rcutree.blimit= [KNL,BOOT]
                         Set maximum number of finished RCU callbacks to process
                         in one batch.
 
-        rcupdate.qhimark=       [KNL,BOOT]
+        rcutree.qhimark=        [KNL,BOOT]
                         Set threshold of queued
                         RCU callbacks over which batch limiting is disabled.
 
-        rcupdate.qlowmark=      [KNL,BOOT]
+        rcutree.qlowmark=       [KNL,BOOT]
                         Set threshold of queued RCU callbacks below which
                         batch limiting is re-enabled.
 
+        rcutree.rcu_cpu_stall_suppress= [KNL,BOOT]
+                        Suppress RCU CPU stall warning messages.
+
+        rcutree.rcu_cpu_stall_timeout= [KNL,BOOT]
+                        Set timeout for RCU CPU stall warning messages.
+
+        rcutorture.fqs_duration= [KNL,BOOT]
+                        Set duration of force_quiescent_state bursts.
+
+        rcutorture.fqs_holdoff= [KNL,BOOT]
+                        Set holdoff time within force_quiescent_state bursts.
+
+        rcutorture.fqs_stutter= [KNL,BOOT]
+                        Set wait time between force_quiescent_state bursts.
+
+        rcutorture.irqreader= [KNL,BOOT]
+                        Test RCU readers from irq handlers.
+
+        rcutorture.n_barrier_cbs= [KNL,BOOT]
+                        Set callbacks/threads for rcu_barrier() testing.
+
+        rcutorture.nfakewriters= [KNL,BOOT]
+                        Set number of concurrent RCU writers.  These just
+                        stress RCU, they don't participate in the actual
+                        test, hence the "fake".
+
+        rcutorture.nreaders= [KNL,BOOT]
+                        Set number of RCU readers.
+
+        rcutorture.onoff_holdoff= [KNL,BOOT]
+                        Set time (s) after boot for CPU-hotplug testing.
+
+        rcutorture.onoff_interval= [KNL,BOOT]
+                        Set time (s) between CPU-hotplug operations, or
+                        zero to disable CPU-hotplug testing.
+
+        rcutorture.shuffle_interval= [KNL,BOOT]
+                        Set task-shuffle interval (s).  Shuffling tasks
+                        allows some CPUs to go into dyntick-idle mode
+                        during the rcutorture test.
+
+        rcutorture.shutdown_secs= [KNL,BOOT]
+                        Set time (s) after boot system shutdown.  This
+                        is useful for hands-off automated testing.
+
+        rcutorture.stall_cpu= [KNL,BOOT]
+                        Duration of CPU stall (s) to test RCU CPU stall
+                        warnings, zero to disable.
+
+        rcutorture.stall_cpu_holdoff= [KNL,BOOT]
+                        Time to wait (s) after boot before inducing stall.
+
+        rcutorture.stat_interval= [KNL,BOOT]
+                        Time (s) between statistics printk()s.
+
+        rcutorture.stutter= [KNL,BOOT]
+                        Time (s) to stutter testing, for example, specifying
+                        five seconds causes the test to run for five seconds,
+                        wait for five seconds, and so on.  This tests RCU's
+                        ability to transition abruptly to and from idle.
+
+        rcutorture.test_boost= [KNL,BOOT]
+                        Test RCU priority boosting?  0=no, 1=maybe, 2=yes.
+                        "Maybe" means test if the RCU implementation
+                        under test support RCU priority boosting.
+
+        rcutorture.test_boost_duration= [KNL,BOOT]
+                        Duration (s) of each individual boost test.
+
+        rcutorture.test_boost_interval= [KNL,BOOT]
+                        Interval (s) between each boost test.
+
+        rcutorture.test_no_idle_hz= [KNL,BOOT]
+                        Test RCU's dyntick-idle handling.  See also the
+                        rcutorture.shuffle_interval parameter.
+
+        rcutorture.torture_type= [KNL,BOOT]
+                        Specify the RCU implementation to test.
+
+        rcutorture.verbose= [KNL,BOOT]
+                        Enable additional printk() statements.
+
         rdinit=         [KNL]