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

Pull RCU updates from Ingo Molnar:
 "The sole purpose of these changes is to shrink and simplify the RCU
  code base, which has suffered from creeping bloat over the past couple
  of years. The end result is a net removal of ~2700 lines of code:

     79 files changed, 1496 insertions(+), 4211 deletions(-)

  Plus there's a marked reduction in the Kconfig space complexity as
  well, here's the number of matches on 'grep RCU' in the .config:

                               before       after

     x86-defconfig                 17          15
     x86-allmodconfig              33          20"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (86 commits)
  rcu: Remove RCU CPU stall warnings from Tiny RCU
  rcu: Remove event tracing from Tiny RCU
  rcu: Move RCU debug Kconfig options to kernel/rcu
  rcu: Move RCU non-debug Kconfig options to kernel/rcu
  rcu: Eliminate NOCBs CPU-state Kconfig options
  rcu: Remove debugfs tracing
  srcu: Remove Classic SRCU
  srcu: Fix rcutorture-statistics typo
  rcu: Remove SPARSE_RCU_POINTER Kconfig option
  rcu: Remove the now-obsolete PROVE_RCU_REPEATEDLY Kconfig option
  rcu: Remove typecheck() from RCU locking wrapper functions
  rcu: Remove #ifdef moving rcu_end_inkernel_boot from rcupdate.h
  rcu: Remove nohz_full full-system-idle state machine
  rcu: Remove the RCU_KTHREAD_PRIO Kconfig option
  rcu: Remove *_SLOW_* Kconfig options
  srcu: Use rnp->lock wrappers to replace explicit memory barriers
  rcu: Move rnp->lock wrappers for SRCU use
  rcu: Convert rnp->lock wrappers to macros for SRCU use
  rcu: Refactor #includes from include/linux/rcupdate.h
  bcm47xx: Fix build regression
  ...

79 files changed, 1496 insertions, 4211 deletions

diff --git a/Documentation/RCU/00-INDEX b/Documentation/RCU/00-INDEX
index 1672573b037a..f46980c060aa 100644
--- a/Documentation/RCU/00-INDEX
+++ b/Documentation/RCU/00-INDEX
@@ -28,8 +28,6 @@ stallwarn.txt
 	- RCU CPU stall warnings (module parameter rcu_cpu_stall_suppress)
 torture.txt
 	- RCU Torture Test Operation (CONFIG_RCU_TORTURE_TEST)
-trace.txt
-	- CONFIG_RCU_TRACE debugfs files and formats
 UP.txt
 	- RCU on Uniprocessor Systems
 whatisRCU.txt
diff --git a/Documentation/RCU/Design/Requirements/Requirements.html b/Documentation/RCU/Design/Requirements/Requirements.html
index f60adf112663..95b30fa25d56 100644
--- a/Documentation/RCU/Design/Requirements/Requirements.html
+++ b/Documentation/RCU/Design/Requirements/Requirements.html
@@ -559,9 +559,7 @@ The <tt>rcu_access_pointer()</tt> on line&nbsp;6 is similar to
 	For <tt>remove_gp_synchronous()</tt>, as long as all modifications
 	to <tt>gp</tt> are carried out while holding <tt>gp_lock</tt>,
 	the above optimizations are harmless.
-	However,
-	with <tt>CONFIG_SPARSE_RCU_POINTER=y</tt>,
-	<tt>sparse</tt> will complain if you
+	However, <tt>sparse</tt> will complain if you
 	define <tt>gp</tt> with <tt>__rcu</tt> and then
 	access it without using
 	either <tt>rcu_access_pointer()</tt> or <tt>rcu_dereference()</tt>.
@@ -1849,7 +1847,8 @@ mass storage, or user patience, whichever comes first.
 If the nesting is not visible to the compiler, as is the case with
 mutually recursive functions each in its own translation unit,
 stack overflow will result.
-If the nesting takes the form of loops, either the control variable
+If the nesting takes the form of loops, perhaps in the guise of tail
+recursion, either the control variable
 will overflow or (in the Linux kernel) you will get an RCU CPU stall warning.
 Nevertheless, this class of RCU implementations is one
 of the most composable constructs in existence.
@@ -1977,9 +1976,8 @@ guard against mishaps and misuse:
 	and <tt>rcu_dereference()</tt>, perhaps (incorrectly)
 	substituting a simple assignment.
 	To catch this sort of error, a given RCU-protected pointer may be
-	tagged with <tt>__rcu</tt>, after which running sparse
-	with <tt>CONFIG_SPARSE_RCU_POINTER=y</tt> will complain
-	about simple-assignment accesses to that pointer.
+	tagged with <tt>__rcu</tt>, after which sparse
+	will complain about simple-assignment accesses to that pointer.
 	Arnd Bergmann made me aware of this requirement, and also
 	supplied the needed
 	<a href="https://lwn.net/Articles/376011/">patch series</a>.
@@ -2036,7 +2034,7 @@ guard against mishaps and misuse:
 	some other synchronization mechanism, for example, reference
 	counting.
 <li>	In kernels built with <tt>CONFIG_RCU_TRACE=y</tt>, RCU-related
-	information is provided via both debugfs and event tracing.
+	information is provided via event tracing.
 <li>	Open-coded use of <tt>rcu_assign_pointer()</tt> and
 	<tt>rcu_dereference()</tt> to create typical linked
 	data structures can be surprisingly error-prone.
@@ -2519,11 +2517,7 @@ It is similarly socially unacceptable to interrupt an
 <tt>nohz_full</tt> CPU running in userspace.
 RCU must therefore track <tt>nohz_full</tt> userspace
 execution.
-And in
-<a href="https://lwn.net/Articles/558284/"><tt>CONFIG_NO_HZ_FULL_SYSIDLE=y</tt></a>
-kernels, RCU must separately track idle CPUs on the one hand and
-CPUs that are either idle or executing in userspace on the other.
-In both cases, RCU must be able to sample state at two points in
+RCU must therefore be able to sample state at two points in
 time, and be able to determine whether or not some other CPU spent
 any time idle and/or executing in userspace.
 
@@ -2936,6 +2930,20 @@ to whether or not a CPU is online, which means that <tt>srcu_barrier()</tt>
 need not exclude CPU-hotplug operations.
 
 <p>
+SRCU also differs from other RCU flavors in that SRCU's expedited and
+non-expedited grace periods are implemented by the same mechanism.
+This means that in the current SRCU implementation, expediting a
+future grace period has the side effect of expediting all prior
+grace periods that have not yet completed.
+(But please note that this is a property of the current implementation,
+not necessarily of future implementations.)
+In addition, if SRCU has been idle for longer than the interval
+specified by the <tt>srcutree.exp_holdoff</tt> kernel boot parameter
+(25&nbsp;microseconds by default),
+and if a <tt>synchronize_srcu()</tt> invocation ends this idle period,
+that invocation will be automatically expedited.
+
+<p>
 As of v4.12, SRCU's callbacks are maintained per-CPU, eliminating
 a locking bottleneck present in prior kernel versions.
 Although this will allow users to put much heavier stress on
diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt
index 877947130ebe..6beda556faf3 100644
--- a/Documentation/RCU/checklist.txt
+++ b/Documentation/RCU/checklist.txt
@@ -413,11 +413,11 @@ over a rather long period of time, but improvements are always welcome!
 	read-side critical sections.  It is the responsibility of the
 	RCU update-side primitives to deal with this.
 
-17.	Use CONFIG_PROVE_RCU, CONFIG_DEBUG_OBJECTS_RCU_HEAD, and the
-	__rcu sparse checks (enabled by CONFIG_SPARSE_RCU_POINTER) to
-	validate your RCU code.  These can help find problems as follows:
+17.	Use CONFIG_PROVE_LOCKING, CONFIG_DEBUG_OBJECTS_RCU_HEAD, and the
+	__rcu sparse checks to validate your RCU code.	These can help
+	find problems as follows:
 
-	CONFIG_PROVE_RCU: check that accesses to RCU-protected data
+	CONFIG_PROVE_LOCKING: check that accesses to RCU-protected data
 		structures are carried out under the proper RCU
 		read-side critical section, while holding the right
 		combination of locks, or whatever other conditions
diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt
deleted file mode 100644
index 6549012033f9..000000000000
--- a/Documentation/RCU/trace.txt
+++ /dev/null
@@ -1,535 +0,0 @@
-CONFIG_RCU_TRACE debugfs Files and Formats
-
-
-The rcutree and rcutiny implementations of RCU provide debugfs trace
-output that summarizes counters and state.  This information is useful for
-debugging RCU itself, and can sometimes also help to debug abuses of RCU.
-The following sections describe the debugfs files and formats, first
-for rcutree and next for rcutiny.
-
-
-CONFIG_TREE_RCU and CONFIG_PREEMPT_RCU debugfs Files and Formats
-
-These implementations of RCU provide several debugfs directories under the
-top-level directory "rcu":
-
-rcu/rcu_bh
-rcu/rcu_preempt
-rcu/rcu_sched
-
-Each directory contains files for the corresponding flavor of RCU.
-Note that rcu/rcu_preempt is only present for CONFIG_PREEMPT_RCU.
-For CONFIG_TREE_RCU, the RCU flavor maps onto the RCU-sched flavor,
-so that activity for both appears in rcu/rcu_sched.
-
-In addition, the following file appears in the top-level directory:
-rcu/rcutorture.  This file displays rcutorture test progress.  The output
-of "cat rcu/rcutorture" looks as follows:
-
-rcutorture test sequence: 0 (test in progress)
-rcutorture update version number: 615
-
-The first line shows the number of rcutorture tests that have completed
-since boot.  If a test is currently running, the "(test in progress)"
-string will appear as shown above.  The second line shows the number of
-update cycles that the current test has started, or zero if there is
-no test in progress.
-
-
-Within each flavor directory (rcu/rcu_bh, rcu/rcu_sched, and possibly
-also rcu/rcu_preempt) the following files will be present:
-
-rcudata:
-	Displays fields in struct rcu_data.
-rcuexp:
-	Displays statistics for expedited grace periods.
-rcugp:
-	Displays grace-period counters.
-rcuhier:
-	Displays the struct rcu_node hierarchy.
-rcu_pending:
-	Displays counts of the reasons rcu_pending() decided that RCU had
-	work to do.
-rcuboost:
-	Displays RCU boosting statistics.  Only present if
-	CONFIG_RCU_BOOST=y.
-
-The output of "cat rcu/rcu_preempt/rcudata" looks as follows:
-
-  0!c=30455 g=30456 cnq=1/0:1 dt=126535/140000000000000/0 df=2002 of=4 ql=0/0 qs=N... b=10 ci=74572 nci=0 co=1131 ca=716
-  1!c=30719 g=30720 cnq=1/0:0 dt=132007/140000000000000/0 df=1874 of=10 ql=0/0 qs=N... b=10 ci=123209 nci=0 co=685 ca=982
-  2!c=30150 g=30151 cnq=1/1:1 dt=138537/140000000000000/0 df=1707 of=8 ql=0/0 qs=N... b=10 ci=80132 nci=0 co=1328 ca=1458
-  3 c=31249 g=31250 cnq=1/1:0 dt=107255/140000000000000/0 df=1749 of=6 ql=0/450 qs=NRW. b=10 ci=151700 nci=0 co=509 ca=622
-  4!c=29502 g=29503 cnq=1/0:1 dt=83647/140000000000000/0 df=965 of=5 ql=0/0 qs=N... b=10 ci=65643 nci=0 co=1373 ca=1521
-  5 c=31201 g=31202 cnq=1/0:1 dt=70422/0/0 df=535 of=7 ql=0/0 qs=.... b=10 ci=58500 nci=0 co=764 ca=698
-  6!c=30253 g=30254 cnq=1/0:1 dt=95363/140000000000000/0 df=780 of=5 ql=0/0 qs=N... b=10 ci=100607 nci=0 co=1414 ca=1353
-  7 c=31178 g=31178 cnq=1/0:0 dt=91536/0/0 df=547 of=4 ql=0/0 qs=.... b=10 ci=109819 nci=0 co=1115 ca=969
-
-This file has one line per CPU, or eight for this 8-CPU system.
-The fields are as follows:
-
-o	The number at the beginning of each line is the CPU number.
-	CPUs numbers followed by an exclamation mark are offline,
-	but have been online at least once since boot.	There will be
-	no output for CPUs that have never been online, which can be
-	a good thing in the surprisingly common case where NR_CPUS is
-	substantially larger than the number of actual CPUs.
-
-o	"c" is the count of grace periods that this CPU believes have
-	completed.  Offlined CPUs and CPUs in dynticks idle mode may lag
-	quite a ways behind, for example, CPU 4 under "rcu_sched" above,
-	which has been offline through 16 RCU grace periods.  It is not
-	unusual to see offline CPUs lagging by thousands of grace periods.
-	Note that although the grace-period number is an unsigned long,
-	it is printed out as a signed long to allow more human-friendly
-	representation near boot time.
-
-o	"g" is the count of grace periods that this CPU believes have
-	started.  Again, offlined CPUs and CPUs in dynticks idle mode
-	may lag behind.  If the "c" and "g" values are equal, this CPU
-	has already reported a quiescent state for the last RCU grace
-	period that it is aware of, otherwise, the CPU believes that it
-	owes RCU a quiescent state.
-
-o	"pq" indicates that this CPU has passed through a quiescent state
-	for the current grace period.  It is possible for "pq" to be
-	"1" and "c" different than "g", which indicates that although
-	the CPU has passed through a quiescent state, either (1) this
-	CPU has not yet reported that fact, (2) some other CPU has not
-	yet reported for this grace period, or (3) both.
-
-o	"qp" indicates that RCU still expects a quiescent state from
-	this CPU.  Offlined CPUs and CPUs in dyntick idle mode might
-	well have qp=1, which is OK: RCU is still ignoring them.
-
-o	"dt" is the current value of the dyntick counter that is incremented
-	when entering or leaving idle, either due to a context switch or
-	due to an interrupt.  This number is even if the CPU is in idle
-	from RCU's viewpoint and odd otherwise.  The number after the
-	first "/" is the interrupt nesting depth when in idle state,
-	or a large number added to the interrupt-nesting depth when
-	running a non-idle task.  Some architectures do not accurately
-	count interrupt nesting when running in non-idle kernel context,
-	which can result in interesting anomalies such as negative
-	interrupt-nesting levels.  The number after the second "/"
-	is the NMI nesting depth.
-
-o	"df" is the number of times that some other CPU has forced a
-	quiescent state on behalf of this CPU due to this CPU being in
-	idle state.
-
-o	"of" is the number of times that some other CPU has forced a
-	quiescent state on behalf of this CPU due to this CPU being
-	offline.  In a perfect world, this might never happen, but it
-	turns out that offlining and onlining a CPU can take several grace
-	periods, and so there is likely to be an extended period of time
-	when RCU believes that the CPU is online when it really is not.
-	Please note that erring in the other direction (RCU believing a
-	CPU is offline when it is really alive and kicking) is a fatal
-	error, so it makes sense to err conservatively.
-
-o	"ql" is the number of RCU callbacks currently residing on
-	this CPU.  The first number is the number of "lazy" callbacks
-	that are known to RCU to only be freeing memory, and the number
-	after the "/" is the total number of callbacks, lazy or not.
-	These counters count callbacks regardless of what phase of
-	grace-period processing that they are in (new, waiting for
-	grace period to start, waiting for grace period to end, ready
-	to invoke).
-
-o	"qs" gives an indication of the state of the callback queue
-	with four characters:
-
-	"N"	Indicates that there are callbacks queued that are not
-		ready to be handled by the next grace period, and thus
-		will be handled by the grace period following the next
-		one.
-
-	"R"	Indicates that there are callbacks queued that are
-		ready to be handled by the next grace period.
-
-	"W"	Indicates that there are callbacks queued that are
-		waiting on the current grace period.
-
-	"D"	Indicates that there are callbacks queued that have
-		already been handled by a prior grace period, and are
-		thus waiting to be invoked.  Note that callbacks in
-		the process of being invoked are not counted here.
-		Callbacks in the process of being invoked are those
-		that have been removed from the rcu_data structures
-		queues by rcu_do_batch(), but which have not yet been
-		invoked.
-
-	If there are no callbacks in a given one of the above states,
-	the corresponding character is replaced by ".".
-
-o	"b" is the batch limit for this CPU.  If more than this number
-	of RCU callbacks is ready to invoke, then the remainder will
-	be deferred.
-
-o	"ci" is the number of RCU callbacks that have been invoked for
-	this CPU.  Note that ci+nci+ql is the number of callbacks that have
-	been registered in absence of CPU-hotplug activity.
-
-o	"nci" is the number of RCU callbacks that have been offloaded from
-	this CPU.  This will always be zero unless the kernel was built
-	with CONFIG_RCU_NOCB_CPU=y and the "rcu_nocbs=" kernel boot
-	parameter was specified.
-
-o	"co" is the number of RCU callbacks that have been orphaned due to
-	this CPU going offline.  These orphaned callbacks have been moved
-	to an arbitrarily chosen online CPU.
-
-o	"ca" is the number of RCU callbacks that have been adopted by this
-	CPU due to other CPUs going offline.  Note that ci+co-ca+ql is
-	the number of RCU callbacks registered on this CPU.
-
-
-Kernels compiled with CONFIG_RCU_BOOST=y display the following from
-/debug/rcu/rcu_preempt/rcudata:
-
-  0!c=12865 g=12866 cnq=1/0:1 dt=83113/140000000000000/0 df=288 of=11 ql=0/0 qs=N... kt=0/O ktl=944 b=10 ci=60709 nci=0 co=748 ca=871
-  1 c=14407 g=14408 cnq=1/0:0 dt=100679/140000000000000/0 df=378 of=7 ql=0/119 qs=NRW. kt=0/W ktl=9b6 b=10 ci=109740 nci=0 co=589 ca=485
-  2 c=14407 g=14408 cnq=1/0:0 dt=105486/0/0 df=90 of=9 ql=0/89 qs=NRW. kt=0/W ktl=c0c b=10 ci=83113 nci=0 co=533 ca=490
-  3 c=14407 g=14408 cnq=1/0:0 dt=107138/0/0 df=142 of=8 ql=0/188 qs=NRW. kt=0/W ktl=b96 b=10 ci=121114 nci=0 co=426 ca=290
-  4 c=14405 g=14406 cnq=1/0:1 dt=50238/0/0 df=706 of=7 ql=0/0 qs=.... kt=0/W ktl=812 b=10 ci=34929 nci=0 co=643 ca=114
-  5!c=14168 g=14169 cnq=1/0:0 dt=45465/140000000000000/0 df=161 of=11 ql=0/0 qs=N... kt=0/O ktl=b4d b=10 ci=47712 nci=0 co=677 ca=722
-  6 c=14404 g=14405 cnq=1/0:0 dt=59454/0/0 df=94 of=6 ql=0/0 qs=.... kt=0/W ktl=e57 b=10 ci=55597 nci=0 co=701 ca=811
-  7 c=14407 g=14408 cnq=1/0:1 dt=68850/0/0 df=31 of=8 ql=0/0 qs=.... kt=0/W ktl=14bd b=10 ci=77475 nci=0 co=508 ca=1042
-
-This is similar to the output discussed above, but contains the following
-additional fields:
-
-o	"kt" is the per-CPU kernel-thread state.  The digit preceding