Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RCU changes from Ingo Molnar:
 "This is 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."

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
  rcu: Make rcu_barrier() less disruptive
  rcu: Explicitly initialize RCU_FAST_NO_HZ per-CPU variables
  rcu: Make RCU_FAST_NO_HZ handle timer migration
  rcu: Update RCU maintainership
  rcu: Make exit_rcu() more precise and consolidate
  rcu: Move PREEMPT_RCU preemption to switch_to() invocation
  rcu: Ensure that RCU_FAST_NO_HZ timers expire on correct CPU
  rcu: Add rcutorture test for call_srcu()
  rcu: Implement per-domain single-threaded call_srcu() state machine
  rcu: Use single value to handle expedited SRCU grace periods
  rcu: Improve srcu_readers_active_idx()'s cache locality
  rcu: Remove unused srcu_barrier()
  rcu: Implement a variant of Peter's SRCU algorithm
  rcu: Improve SRCU's wait_idx() comments
  rcu: Flip ->completed only once per SRCU grace period
  rcu: Increment upper bit only for srcu_read_lock()
  rcu: Remove fast check path from __synchronize_srcu()
  rcu: Direct algorithmic SRCU implementation
  rcu: Introduce rcutorture testing for rcu_barrier()
  timer: Fix mod_timer_pinned() header comment
  ...

2 files changed, 99 insertions, 4 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 f995195409fd..0e90453e4acb 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2333,18 +2333,100 @@ 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]
 			Format: <full_path>
 			Run specified binary instead of /init from the ramdisk,