Merge commit '683b6c6f82a60fabf47012581c2cfbf1b037ab95' into stable/f…

…or-linus-3.15

This merge of the irq-core-for-linus branch broke the ARM build when
Xen is enabled.

Conflicts:
	drivers/xen/events/events_base.c

Documentation/RCU/RTFP.txt

@@ -31,6 +31,14 @@ has lapsed, so this approach may be used in non-GPL software, if desired.
 (In contrast, implementation of RCU is permitted only in software licensed
 under either GPL or LGPL.  Sorry!!!)
 
+In 1987, Rashid et al. described lazy TLB-flush [RichardRashid87a].
+At first glance, this has nothing to do with RCU, but nevertheless
+this paper helped inspire the update-side batching used in the later
+RCU implementation in DYNIX/ptx.  In 1988, Barbara Liskov published
+a description of Argus that noted that use of out-of-date values can
+be tolerated in some situations.  Thus, this paper provides some early
+theoretical justification for use of stale data.
+
 In 1990, Pugh [Pugh90] noted that explicitly tracking which threads
 were reading a given data structure permitted deferred free to operate
 in the presence of non-terminating threads.  However, this explicit
@@ -41,11 +49,11 @@ providing a fine-grained locking design, however, it would be interesting
 to see how much of the performance advantage reported in 1990 remains
 today.
 
-At about this same time, Adams [Adams91] described ``chaotic relaxation'',
-where the normal barriers between successive iterations of convergent
-numerical algorithms are relaxed, so that iteration $n$ might use
-data from iteration $n-1$ or even $n-2$.  This introduces error,
-which typically slows convergence and thus increases the number of
+At about this same time, Andrews [Andrews91textbook] described ``chaotic
+relaxation'', where the normal barriers between successive iterations
+of convergent numerical algorithms are relaxed, so that iteration $n$
+might use data from iteration $n-1$ or even $n-2$.  This introduces
+error, which typically slows convergence and thus increases the number of
 iterations required.  However, this increase is sometimes more than made
 up for by a reduction in the number of expensive barrier operations,
 which are otherwise required to synchronize the threads at the end
@@ -55,7 +63,8 @@ is thus inapplicable to most data structures in operating-system kernels.
 
 In 1992, Henry (now Alexia) Massalin completed a dissertation advising
 parallel programmers to defer processing when feasible to simplify
-synchronization.  RCU makes extremely heavy use of this advice.
+synchronization [HMassalinPhD].  RCU makes extremely heavy use of
+this advice.
 
 In 1993, Jacobson [Jacobson93] verbally described what is perhaps the
 simplest deferred-free technique: simply waiting a fixed amount of time
@@ -90,27 +99,29 @@ mechanism, which is quite similar to RCU [Gamsa99].  These operating
 systems made pervasive use of RCU in place of "existence locks", which
 greatly simplifies locking hierarchies and helps avoid deadlocks.
 
-2001 saw the first RCU presentation involving Linux [McKenney01a]
-at OLS.  The resulting abundance of RCU patches was presented the
-following year [McKenney02a], and use of RCU in dcache was first
-described that same year [Linder02a].
+The year 2000 saw an email exchange that would likely have
+led to yet another independent invention of something like RCU
+[RustyRussell2000a,RustyRussell2000b].  Instead, 2001 saw the first
+RCU presentation involving Linux [McKenney01a] at OLS.  The resulting
+abundance of RCU patches was presented the following year [McKenney02a],
+and use of RCU in dcache was first described that same year [Linder02a].
 
 Also in 2002, Michael [Michael02b,Michael02a] presented "hazard-pointer"
 techniques that defer the destruction of data structures to simplify
 non-blocking synchronization (wait-free synchronization, lock-free
 synchronization, and obstruction-free synchronization are all examples of
-non-blocking synchronization).  In particular, this technique eliminates
-locking, reduces contention, reduces memory latency for readers, and
-parallelizes pipeline stalls and memory latency for writers.  However,
-these techniques still impose significant read-side overhead in the
-form of memory barriers.  Researchers at Sun worked along similar lines
-in the same timeframe [HerlihyLM02].  These techniques can be thought
-of as inside-out reference counts, where the count is represented by the
-number of hazard pointers referencing a given data structure rather than
-the more conventional counter field within the data structure itself.
-The key advantage of inside-out reference counts is that they can be
-stored in immortal variables, thus allowing races between access and
-deletion to be avoided.
+non-blocking synchronization).  The corresponding journal article appeared
+in 2004 [MagedMichael04a].  This technique eliminates locking, reduces
+contention, reduces memory latency for readers, and parallelizes pipeline
+stalls and memory latency for writers.  However, these techniques still
+impose significant read-side overhead in the form of memory barriers.
+Researchers at Sun worked along similar lines in the same timeframe
+[HerlihyLM02].  These techniques can be thought of as inside-out reference
+counts, where the count is represented by the number of hazard pointers
+referencing a given data structure rather than the more conventional
+counter field within the data structure itself.  The key advantage
+of inside-out reference counts is that they can be stored in immortal
+variables, thus allowing races between access and deletion to be avoided.
 
 By the same token, RCU can be thought of as a "bulk reference count",
 where some form of reference counter covers all reference by a given CPU
@@ -123,8 +134,10 @@ can be thought of in other terms as well.
 
 In 2003, the K42 group described how RCU could be used to create
 hot-pluggable implementations of operating-system functions [Appavoo03a].
-Later that year saw a paper describing an RCU implementation of System
-V IPC [Arcangeli03], and an introduction to RCU in Linux Journal
+Later that year saw a paper describing an RCU implementation
+of System V IPC [Arcangeli03] (following up on a suggestion by
+Hugh Dickins [Dickins02a] and an implementation by Mingming Cao
+[MingmingCao2002IPCRCU]), and an introduction to RCU in Linux Journal
 [McKenney03a].
 
 2004 has seen a Linux-Journal article on use of RCU in dcache
@@ -383,6 +396,21 @@ for Programming Languages and Operating Systems}"
 }
 }
 
+@phdthesis{HMassalinPhD
+,author="H. Massalin"
+,title="Synthesis: An Efficient Implementation of Fundamental Operating
+System Services"
+,school="Columbia University"
+,address="New York, NY"
+,year="1992"
+,annotation={
+	Mondo optimizing compiler.
+	Wait-free stuff.
+	Good advice: defer work to avoid synchronization.  See page 90
+		(PDF page 106), Section 5.4, fourth bullet point.
+}
+}
+
 @unpublished{Jacobson93
 ,author="Van Jacobson"
 ,title="Avoid Read-Side Locking Via Delayed Free"
@@ -671,6 +699,20 @@ Orran Krieger and Rusty Russell and Dipankar Sarma and Maneesh Soni"
 [Viewed October 18, 2004]"
 }
 
+@conference{Michael02b
+,author="Maged M. Michael"
+,title="High Performance Dynamic Lock-Free Hash Tables and List-Based Sets"
+,Year="2002"
+,Month="August"
+,booktitle="{Proceedings of the 14\textsuperscript{th} Annual ACM
+Symposium on Parallel
+Algorithms and Architecture}"
+,pages="73-82"
+,annotation={
+Like the title says...
+}
+}
+
 @Conference{Linder02a
 ,Author="Hanna Linder and Dipankar Sarma and Maneesh Soni"
 ,Title="Scalability of the Directory Entry Cache"
@@ -727,6 +769,24 @@ Andrea Arcangeli and Andi Kleen and Orran Krieger and Rusty Russell"
 }
 }
 
+@conference{Michael02a
+,author="Maged M. Michael"
+,title="Safe Memory Reclamation for Dynamic Lock-Free Objects Using Atomic
+Reads and Writes"
+,Year="2002"
+,Month="August"
+,booktitle="{Proceedings of the 21\textsuperscript{st} Annual ACM
+Symposium on Principles of Distributed Computing}"
+,pages="21-30"
+,annotation={
+	Each thread keeps an array of pointers to items that it is
+	currently referencing.	Sort of an inside-out garbage collection
+	mechanism, but one that requires the accessing code to explicitly
+	state its needs.  Also requires read-side memory barriers on
+	most architectures.
+}
+}
+
 @unpublished{Dickins02a
 ,author="Hugh Dickins"
 ,title="Use RCU for System-V IPC"
@@ -735,6 +795,17 @@ Andrea Arcangeli and Andi Kleen and Orran Krieger and Rusty Russell"
 ,note="private communication"
 }
 
+@InProceedings{HerlihyLM02
+,author={Maurice Herlihy and Victor Luchangco and Mark Moir}
+,title="The Repeat Offender Problem: A Mechanism for Supporting Dynamic-Sized,
+Lock-Free Data Structures"
+,booktitle={Proceedings of 16\textsuperscript{th} International
+Symposium on Distributed Computing}
+,year=2002
+,month="October"
+,pages="339-353"
+}
+
 @unpublished{Sarma02b
 ,Author="Dipankar Sarma"
 ,Title="Some dcache\_rcu benchmark numbers"
@@ -749,6 +820,19 @@ Andrea Arcangeli and Andi Kleen and Orran Krieger and Rusty Russell"
 }
 }
 
+@unpublished{MingmingCao2002IPCRCU
+,Author="Mingming Cao"
+,Title="[PATCH]updated ipc lock patch"
+,month="October"
+,year="2002"
+,note="Available:
+\url{https://lkml.org/lkml/2002/10/24/262}
+[Viewed February 15, 2014]"
+,annotation={
+	Mingming Cao's patch to introduce RCU to SysV IPC.
+}
+}
+
 @unpublished{LinusTorvalds2003a
 ,Author="Linus Torvalds"
 ,Title="Re: {[PATCH]} small fixes in brlock.h"
@@ -982,6 +1066,23 @@ Realtime Applications"
 }
 }
 
+@article{MagedMichael04a
+,author="Maged M. Michael"
+,title="Hazard Pointers: Safe Memory Reclamation for Lock-Free Objects"
+,Year="2004"
+,Month="June"
+,journal="IEEE Transactions on Parallel and Distributed Systems"
+,volume="15"
+,number="6"
+,pages="491-504"
+,url="Available:
+\url{http://www.research.ibm.com/people/m/michael/ieeetpds-2004.pdf}
+[Viewed March 1, 2005]"
+,annotation={
+	New canonical hazard-pointer citation.
+}
+}
+
 @phdthesis{PaulEdwardMcKenneyPhD
 ,author="Paul E. McKenney"
 ,title="Exploiting Deferred Destruction:

Documentation/RCU/checklist.txt

@@ -256,10 +256,10 @@ over a rather long period of time, but improvements are always welcome!
 		variations on this theme.
 
 	b.	Limiting update rate.  For example, if updates occur only
-		once per hour, then no explicit rate limiting is required,
-		unless your system is already badly broken.  The dcache
-		subsystem takes this approach -- updates are guarded
-		by a global lock, limiting their rate.
+		once per hour, then no explicit rate limiting is
+		required, unless your system is already badly broken.
+		Older versions of the dcache subsystem take this approach,
+		guarding updates with a global lock, limiting their rate.
 
 	c.	Trusted update -- if updates can only be done manually by
 		superuser or some other trusted user, then it might not
@@ -268,14 +268,22 @@ over a rather long period of time, but improvements are always welcome!
 		the machine.
 
 	d.	Use call_rcu_bh() rather than call_rcu(), in order to take
-		advantage of call_rcu_bh()'s faster grace periods.
+		advantage of call_rcu_bh()'s faster grace periods.  (This
+		is only a partial solution, though.)
 
 	e.	Periodically invoke synchronize_rcu(), permitting a limited
 		number of updates per grace period.
 
 	The same cautions apply to call_rcu_bh(), call_rcu_sched(),
 	call_srcu(), and kfree_rcu().
 
+	Note that although these primitives do take action to avoid memory
+	exhaustion when any given CPU has too many callbacks, a determined
+	user could still exhaust memory.  This is especially the case
+	if a system with a large number of CPUs has been configured to
+	offload all of its RCU callbacks onto a single CPU, or if the
+	system has relatively little free memory.
+
 9.	All RCU list-traversal primitives, which include
 	rcu_dereference(), list_for_each_entry_rcu(), and
 	list_for_each_safe_rcu(), must be either within an RCU read-side

Documentation/arm64/memory.txt

@@ -35,11 +35,13 @@ ffffffbc00000000	ffffffbdffffffff	   8GB		vmemmap
 
 ffffffbe00000000	ffffffbffbbfffff	  ~8GB		[guard, future vmmemap]
 
-ffffffbffbc00000	ffffffbffbdfffff	   2MB		earlyprintk device
+ffffffbffa000000	ffffffbffaffffff	  16MB		PCI I/O space
+
+ffffffbffb000000	ffffffbffbbfffff	  12MB		[guard]
 
-ffffffbffbe00000	ffffffbffbe0ffff	  64KB		PCI I/O space
+ffffffbffbc00000	ffffffbffbdfffff	   2MB		earlyprintk device
 
-ffffffbffbe10000	ffffffbcffffffff	  ~2MB		[guard]
+ffffffbffbe00000	ffffffbffbffffff	   2MB		[guard]
 
 ffffffbffc000000	ffffffbfffffffff	  64MB		modules
 
@@ -60,11 +62,13 @@ fffffdfc00000000	fffffdfdffffffff	   8GB		vmemmap
 
 fffffdfe00000000	fffffdfffbbfffff	  ~8GB		[guard, future vmmemap]
 
-fffffdfffbc00000	fffffdfffbdfffff	   2MB		earlyprintk device
+fffffdfffa000000	fffffdfffaffffff	  16MB		PCI I/O space
+
+fffffdfffb000000	fffffdfffbbfffff	  12MB		[guard]
 
-fffffdfffbe00000	fffffdfffbe0ffff	  64KB		PCI I/O space
+fffffdfffbc00000	fffffdfffbdfffff	   2MB		earlyprintk device
 
-fffffdfffbe10000	fffffdfffbffffff	  ~2MB		[guard]
+fffffdfffbe00000	fffffdfffbffffff	   2MB		[guard]
 
 fffffdfffc000000	fffffdffffffffff	  64MB		modules
 

Documentation/device-mapper/cache.txt

@@ -124,12 +124,11 @@ the default being 204800 sectors (or 100MB).
 Updating on-disk metadata
 -------------------------
 
-On-disk metadata is committed every time a REQ_SYNC or REQ_FUA bio is
-written.  If no such requests are made then commits will occur every
-second.  This means the cache behaves like a physical disk that has a
-write cache (the same is true of the thin-provisioning target).  If
-power is lost you may lose some recent writes.  The metadata should
-always be consistent in spite of any crash.
+On-disk metadata is committed every time a FLUSH or FUA bio is written.
+If no such requests are made then commits will occur every second.  This
+means the cache behaves like a physical disk that has a volatile write
+cache.  If power is lost you may lose some recent writes.  The metadata
+should always be consistent in spite of any crash.
 
 The 'dirty' state for a cache block changes far too frequently for us
 to keep updating it on the fly.  So we treat it as a hint.  In normal

Documentation/device-mapper/thin-provisioning.txt

@@ -116,6 +116,35 @@ Resuming a device with a new table itself triggers an event so the
 userspace daemon can use this to detect a situation where a new table
 already exceeds the threshold.
 
+A low water mark for the metadata device is maintained in the kernel and
+will trigger a dm event if free space on the metadata device drops below
+it.
+
+Updating on-disk metadata
+-------------------------
+
+On-disk metadata is committed every time a FLUSH or FUA bio is written.
+If no such requests are made then commits will occur every second.  This
+means the thin-provisioning target behaves like a physical disk that has
+a volatile write cache.  If power is lost you may lose some recent
+writes.  The metadata should always be consistent in spite of any crash.
+
+If data space is exhausted the pool will either error or queue IO
+according to the configuration (see: error_if_no_space).  If metadata
+space is exhausted or a metadata operation fails: the pool will error IO
+until the pool is taken offline and repair is performed to 1) fix any
+potential inconsistencies and 2) clear the flag that imposes repair.
+Once the pool's metadata device is repaired it may be resized, which
+will allow the pool to return to normal operation.  Note that if a pool
+is flagged as needing repair, the pool's data and metadata devices
+cannot be resized until repair is performed.  It should also be noted
+that when the pool's metadata space is exhausted the current metadata
+transaction is aborted.  Given that the pool will cache IO whose
+completion may have already been acknowledged to upper IO layers
+(e.g. filesystem) it is strongly suggested that consistency checks
+(e.g. fsck) be performed on those layers when repair of the pool is
+required.
+
 Thin provisioning
 -----------------
 
@@ -258,10 +287,9 @@ ii) Status
 	should register for the event and then check the target's status.
 
     held metadata root:
-	The location, in sectors, of the metadata root that has been
+	The location, in blocks, of the metadata root that has been
 	'held' for userspace read access.  '-' indicates there is no
-	held root.  This feature is not yet implemented so '-' is
-	always returned.
+	held root.
 
     discard_passdown|no_discard_passdown
 	Whether or not discards are actually being passed down to the

Documentation/devicetree/bindings/arm/armada-370-xp-mpic.txt

@@ -1,4 +1,4 @@
-Marvell Armada 370 and Armada XP Interrupt Controller
+Marvell Armada 370, 375, 38x, XP Interrupt Controller
 -----------------------------------------------------
 
 Required properties:
@@ -16,7 +16,13 @@ Required properties:
   automatically map to the interrupt controller registers of the
   current CPU)
 
+Optional properties:
 
+- interrupts: If defined, then it indicates that this MPIC is
+  connected as a slave to another interrupt controller. This is
+  typically the case on Armada 375 and Armada 38x, where the MPIC is
+  connected as a slave to the Cortex-A9 GIC. The provided interrupt
+  indicate to which GIC interrupt the MPIC output is connected.
 
 Example: