Documentation updates and fixes

index da6525bdc3f5..6dafc8085acc 100644
@@ -52,7 +52,7 @@ CONTENTS
 
      - Varieties of memory barrier.
      - What may not be assumed about memory barriers?
-     - Data dependency barriers.
+     - Data dependency barriers (historical).
      - Control dependencies.
      - SMP barrier pairing.
      - Examples of memory barrier sequences.

@@ -554,8 +554,15 @@ There are certain things that the Linux kernel memory barriers do not guarantee:
 	    Documentation/DMA-API.txt
 
 
-DATA DEPENDENCY BARRIERS
-------------------------
+DATA DEPENDENCY BARRIERS (HISTORICAL)
+-------------------------------------
+
+As of v4.15 of the Linux kernel, an smp_read_barrier_depends() was
+added to READ_ONCE(), which means that about the only people who
+need to pay attention to this section are those working on DEC Alpha
+architecture-specific code and those working on READ_ONCE() itself.
+For those who need it, and for those who are interested in the history,
+here is the story of data-dependency barriers.
 
 The usage requirements of data dependency barriers are a little subtle, and
 it's not always obvious that they're needed.  To illustrate, consider the

@@ -2843,8 +2850,9 @@ as that committed on CPU 1.
 
 
 To intervene, we need to interpolate a data dependency barrier or a read
-barrier between the loads.  This will force the cache to commit its coherency
-queue before processing any further requests:
+barrier between the loads (which as of v4.15 is supplied unconditionally
+by the READ_ONCE() macro).  This will force the cache to commit its
+coherency queue before processing any further requests:
 
 	CPU 1		CPU 2		COMMENT
 	===============	===============	=======================================

@@ -2873,8 +2881,8 @@ Other CPUs may also have split caches, but must coordinate between the various
 cachelets for normal memory accesses.  The semantics of the Alpha removes the
 need for hardware coordination in the absence of memory barriers, which
 permitted Alpha to sport higher CPU clock rates back in the day.  However,
-please note that smp_read_barrier_depends() should not be used except in
-Alpha arch-specific code and within the READ_ONCE() macro.
+please note that (again, as of v4.15) smp_read_barrier_depends() should not
+be used except in Alpha arch-specific code and within the READ_ONCE() macro.
 
 
 CACHE COHERENCY VS DMA

@@ -3039,7 +3047,9 @@ the data dependency barrier really becomes necessary as this synchronises both
 caches with the memory coherence system, thus making it seem like pointer
 changes vs new data occur in the right order.
 
-The Alpha defines the Linux kernel's memory barrier model.
+The Alpha defines the Linux kernel's memory model, although as of v4.15
+the Linux kernel's addition of smp_read_barrier_depends() to READ_ONCE()
+greatly reduced Alpha's impact on the memory model.
 
 See the subsection on "Cache Coherency" above.
 

index dca7d823ad57..04096fb8b8d9 100644
@@ -32,6 +32,12 @@ IRIW+poonceonces+OnceOnce.litmus
 	order of a pair of writes, where each write is to a different
 	variable by a different process?
 
+ISA2+pooncelock+pooncelock+pombonce.litmus
+	Tests whether the ordering provided by a lock-protected S
+	litmus test is visible to an external process whose accesses are
+	separated by smp_mb().	This addition of an external process to
+	S is otherwise known as ISA2.
+
 ISA2+poonceonces.litmus
 	As below, but with store-release replaced with WRITE_ONCE()
 	and load-acquire replaced with READ_ONCE().

index 04e458acd6d4..956b1ae4aafb 100644
@@ -1,11 +1,11 @@
                                   Prior Operation     Subsequent Operation
                                   ---------------  ---------------------------
                                C  Self  R  W  RWM  Self  R  W  DR  DW  RMW  SV
-                              __  ----  -  -  ---  ----  -  -  --  --  ---  --
+                              --  ----  -  -  ---  ----  -  -  --  --  ---  --
 
 Store, e.g., WRITE_ONCE()            Y                                       Y
-Load, e.g., READ_ONCE()              Y                              Y        Y
-Unsuccessful RMW operation           Y                              Y        Y
+Load, e.g., READ_ONCE()              Y                          Y   Y        Y
+Unsuccessful RMW operation           Y                          Y   Y        Y
 rcu_dereference()                    Y                          Y   Y        Y
 Successful *_acquire()               R                   Y  Y   Y   Y    Y   Y
 Successful *_release()         C        Y  Y    Y     W                      Y

index dae8b8cb2ad3..a727c82bd434 100644
@@ -826,7 +826,7 @@ A-cumulative; they only affect the propagation of stores that are
 executed on C before the fence (i.e., those which precede the fence in
 program order).
 
-read_lock(), rcu_read_unlock(), and synchronize_rcu() fences have
+rcu_read_lock(), rcu_read_unlock(), and synchronize_rcu() fences have
 other properties which we discuss later.
 
 

@@ -1138,7 +1138,7 @@ final effect is that even though the two loads really are executed in
 program order, it appears that they aren't.
 
 This could not have happened if the local cache had processed the
-incoming stores in FIFO order.  In constrast, other architectures
+incoming stores in FIFO order.  By contrast, other architectures
 maintain at least the appearance of FIFO order.
 
 In practice, this difficulty is solved by inserting a special fence

index 5dfb9c7f3462..397e4e67e8c8 100644
@@ -13,7 +13,7 @@ WRITE_ONCE(X,V) { __store{once}(X,V); }
 smp_store_release(X,V) { __store{release}(*X,V); }
 smp_load_acquire(X) __load{acquire}(*X)
 rcu_assign_pointer(X,V) { __store{release}(X,V); }
-rcu_dereference(X) __load{deref}(X)
+rcu_dereference(X) __load{once}(X)
 
 // Fences
 smp_mb() { __fence{mb} ; }

index ea950c566ffd..0b3a5f3c9ccd 100644
@@ -27,21 +27,6 @@ separately:
 
 See "herdtools7/INSTALL.md" for installation instructions.
 
-Alternatively, Abhishek Bhardwaj has kindly provided a Docker image
-of these tools at "abhishek40/memory-model".  Abhishek suggests the
-following commands to install and use this image:
-
-  - Users should install Docker for their distribution.
-  - docker run -itd abhishek40/memory-model
-  - docker attach <id-emitted-from-the-previous-command>
-
-Gentoo users might wish to make use of Patrick McLean's package:
-
-  https://gitweb.gentoo.org/repo/gentoo.git/tree/dev-util/herdtools7
-
-These packages may not be up-to-date with respect to the GitHub
-repository.
-
 
 ==================
 BASIC USAGE: HERD7