11 files changed, 163 insertions, 23 deletions
diff --git a/tools/memory-model/litmus-tests/IRIW+mbonceonces+OnceOnce.litmus b/tools/memory-model/litmus-tests/IRIW+fencembonceonces+OnceOnce.litmus
index 98a3716efa37..e729d2776e89 100644
--- a/tools/memory-model/litmus-tests/IRIW+mbonceonces+OnceOnce.litmus
+++ b/tools/memory-model/litmus-tests/IRIW+fencembonceonces+OnceOnce.litmus
@@ -1,4 +1,4 @@
-C IRIW+mbonceonces+OnceOnce
+C IRIW+fencembonceonces+OnceOnce
 
 (*
  * Result: Never
diff --git a/tools/memory-model/litmus-tests/ISA2+pooncelock+pooncelock+pombonce.litmus b/tools/memory-model/litmus-tests/ISA2+pooncelock+pooncelock+pombonce.litmus
index 7a39a0aaa976..094d58df7789 100644
--- a/tools/memory-model/litmus-tests/ISA2+pooncelock+pooncelock+pombonce.litmus
+++ b/tools/memory-model/litmus-tests/ISA2+pooncelock+pooncelock+pombonce.litmus
@@ -1,11 +1,10 @@
-C ISA2+pooncelock+pooncelock+pombonce.litmus
+C ISA2+pooncelock+pooncelock+pombonce
 
 (*
- * Result: Sometimes
+ * Result: Never
  *
- * This test shows that the ordering provided by a lock-protected S
- * litmus test (P0() and P1()) are not visible to external process P2().
- * This is likely to change soon.
+ * This test shows that write-write ordering provided by locks
+ * (in P0() and P1()) is visible to external process P2().
  *)
 
 {}
diff --git a/tools/memory-model/litmus-tests/LB+ctrlonceonce+mbonceonce.litmus b/tools/memory-model/litmus-tests/LB+fencembonceonce+ctrlonceonce.litmus
index de6708229dd1..4727f5aaf03b 100644
--- a/tools/memory-model/litmus-tests/LB+ctrlonceonce+mbonceonce.litmus
+++ b/tools/memory-model/litmus-tests/LB+fencembonceonce+ctrlonceonce.litmus
@@ -1,4 +1,4 @@
-C LB+ctrlonceonce+mbonceonce
+C LB+fencembonceonce+ctrlonceonce
 
 (*
  * Result: Never
diff --git a/tools/memory-model/litmus-tests/MP+wmbonceonce+rmbonceonce.litmus b/tools/memory-model/litmus-tests/MP+fencewmbonceonce+fencermbonceonce.litmus
index c078f38ff27a..a273da9faa6d 100644
--- a/tools/memory-model/litmus-tests/MP+wmbonceonce+rmbonceonce.litmus
+++ b/tools/memory-model/litmus-tests/MP+fencewmbonceonce+fencermbonceonce.litmus
@@ -1,4 +1,4 @@
-C MP+wmbonceonce+rmbonceonce
+C MP+fencewmbonceonce+fencermbonceonce
 
 (*
  * Result: Never
diff --git a/tools/memory-model/litmus-tests/R+mbonceonces.litmus b/tools/memory-model/litmus-tests/R+fencembonceonces.litmus
index a0e884ad2132..222a0b850b4a 100644
--- a/tools/memory-model/litmus-tests/R+mbonceonces.litmus
+++ b/tools/memory-model/litmus-tests/R+fencembonceonces.litmus
@@ -1,4 +1,4 @@
-C R+mbonceonces
+C R+fencembonceonces
 
 (*
  * Result: Never
diff --git a/tools/memory-model/litmus-tests/README b/tools/memory-model/litmus-tests/README
index 17eb9a8c222d..5ee08f129094 100644
--- a/tools/memory-model/litmus-tests/README
+++ b/tools/memory-model/litmus-tests/README
@@ -1,4 +1,6 @@
-This directory contains the following litmus tests:
+============
+LITMUS TESTS
+============
 
 CoRR+poonceonce+Once.litmus
 	Test of read-read coherence, that is, whether or not two
@@ -18,7 +20,7 @@ CoWW+poonceonce.litmus
 	Test of write-write coherence, that is, whether or not two
 	successive writes to the same variable are ordered.
 
-IRIW+mbonceonces+OnceOnce.litmus
+IRIW+fencembonceonces+OnceOnce.litmus
 	Test of independent reads from independent writes with smp_mb()
 	between each pairs of reads.  In other words, is smp_mb()
 	sufficient to cause two different reading processes to agree on
@@ -36,7 +38,7 @@ IRIW+poonceonces+OnceOnce.litmus
 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
+	separated by smp_mb().  This addition of an external process to
 	S is otherwise known as ISA2.
 
 ISA2+poonceonces.litmus
@@ -47,7 +49,7 @@ ISA2+pooncerelease+poacquirerelease+poacquireonce.litmus
 	Can a release-acquire chain order a prior store against
 	a later load?
 
-LB+ctrlonceonce+mbonceonce.litmus
+LB+fencembonceonce+ctrlonceonce.litmus
 	Does a control dependency and an smp_mb() suffice for the
 	load-buffering litmus test, where each process reads from one
 	of two variables then writes to the other?
@@ -88,14 +90,14 @@ MP+porevlocks.litmus
 	As below, but with the first access of the writer process
 	and the second access of reader process protected by a lock.
 
-MP+wmbonceonce+rmbonceonce.litmus
+MP+fencewmbonceonce+fencermbonceonce.litmus
 	Does a smp_wmb() (between the stores) and an smp_rmb() (between
 	the loads) suffice for the message-passing litmus test, where one
 	process writes data and then a flag, and the other process reads
 	the flag and then the data.  (This is similar to the ISA2 tests,
 	but with two processes instead of three.)
 
-R+mbonceonces.litmus
+R+fencembonceonces.litmus
 	This is the fully ordered (via smp_mb()) version of one of
 	the classic counterintuitive litmus tests that illustrates the
 	effects of store propagation delays.
@@ -103,7 +105,7 @@ R+mbonceonces.litmus
 R+poonceonces.litmus
 	As above, but without the smp_mb() invocations.
 
-SB+mbonceonces.litmus
+SB+fencembonceonces.litmus
 	This is the fully ordered (again, via smp_mb() version of store
 	buffering, which forms the core of Dekker's mutual-exclusion
 	algorithm.
@@ -111,15 +113,24 @@ SB+mbonceonces.litmus
 SB+poonceonces.litmus
 	As above, but without the smp_mb() invocations.
 
+SB+rfionceonce-poonceonces.litmus
+	This litmus test demonstrates that LKMM is not fully multicopy
+	atomic.  (Neither is it other multicopy atomic.)  This litmus test
+	also demonstrates the "locations" debugging aid, which designates
+	additional registers and locations to be printed out in the dump
+	of final states in the herd7 output.  Without the "locations"
+	statement, only those registers and locations mentioned in the
+	"exists" clause will be printed.
+
 S+poonceonces.litmus
 	As below, but without the smp_wmb() and acquire load.
 
-S+wmbonceonce+poacquireonce.litmus
+S+fencewmbonceonce+poacquireonce.litmus
 	Can a smp_wmb(), instead of a release, and an acquire order
 	a prior store against a subsequent store?
 
 WRC+poonceonces+Once.litmus
-WRC+pooncerelease+rmbonceonce+Once.litmus
+WRC+pooncerelease+fencermbonceonce+Once.litmus
 	These two are members of an extension of the MP litmus-test
 	class in which the first write is moved to a separate process.
 	The second is forbidden because smp_store_release() is
@@ -134,7 +145,7 @@ Z6.0+pooncelock+poonceLock+pombonce.litmus
 	As above, but with smp_mb__after_spinlock() immediately
 	following the spin_lock().
 
-Z6.0+pooncerelease+poacquirerelease+mbonceonce.litmus
+Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus
 	Is the ordering provided by a release-acquire chain sufficient
 	to make ordering apparent to accesses by a process that does
 	not participate in that release-acquire chain?
@@ -142,3 +153,101 @@ Z6.0+pooncerelease+poacquirerelease+mbonceonce.litmus
 A great many more litmus tests are available here:
 
 	https://github.com/paulmckrcu/litmus
+
+==================
+LITMUS TEST NAMING
+==================
+
+Litmus tests are usually named based on their contents, which means that
+looking at the name tells you what the litmus test does.  The naming
+scheme covers litmus tests having a single cycle that passes through
+each process exactly once, so litmus tests not fitting this description
+are named on an ad-hoc basis.
+
+The structure of a litmus-test name is the litmus-test class, a plus
+sign ("+"), and one string for each process, separated by plus signs.
+The end of the name is ".litmus".
+
+The litmus-test classes may be found in the infamous test6.pdf:
+https://www.cl.cam.ac.uk/~pes20/ppc-supplemental/test6.pdf
+Each class defines the pattern of accesses and of the variables accessed.
+For example, if the one process writes to a pair of variables, and
+the other process reads from these same variables, the corresponding
+litmus-test class is "MP" (message passing), which may be found on the
+left-hand end of the second row of tests on page one of test6.pdf.
+
+The strings used to identify the actions carried out by each process are
+complex due to a desire to have short(er) names.  Thus, there is a tool to
+generate these strings from a given litmus test's actions.  For example,
+consider the processes from SB+rfionceonce-poonceonces.litmus:
+
+	P0(int *x, int *y)
+	{
+		int r1;
+		int r2;
+
+		WRITE_ONCE(*x, 1);
+		r1 = READ_ONCE(*x);
+		r2 = READ_ONCE(*y);
+	}
+
+	P1(int *x, int *y)
+	{
+		int r3;
+		int r4;
+
+		WRITE_ONCE(*y, 1);
+		r3 = READ_ONCE(*y);
+		r4 = READ_ONCE(*x);
+	}
+
+The next step is to construct a space-separated list of descriptors,
+interleaving descriptions of the relation between a pair of consecutive
+accesses with descriptions of the second access in the pair.
+
+P0()'s WRITE_ONCE() is read by its first READ_ONCE(), which is a
+reads-from link (rf) and internal to the P0() process.  This is
+"rfi", which is an abbreviation for "reads-from internal".  Because
+some of the tools string these abbreviations together with space
+characters separating processes, the first character is capitalized,
+resulting in "Rfi".
+
+P0()'s second access is a READ_ONCE(), as opposed to (for example)
+smp_load_acquire(), so next is "Once".  Thus far, we have "Rfi Once".
+
+P0()'s third access is also a READ_ONCE(), but to y rather than x.
+This is related to P0()'s second access by program order ("po"),
+to a different variable ("d"), and both accesses are reads ("RR").
+The resulting descriptor is "PodRR".  Because P0()'s third access is
+READ_ONCE(), we add another "Once" descriptor.
+
+A from-read ("fre") relation links P0()'s third to P1()'s first
+access, and the resulting descriptor is "Fre".  P1()'s first access is
+WRITE_ONCE(), which as before gives the descriptor "Once".  The string
+thus far is thus "Rfi Once PodRR Once Fre Once".
+
+The remainder of P1() is similar to P0(), which means we add
+"Rfi Once PodRR Once".  Another fre links P1()'s last access to
+P0()'s first access, which is WRITE_ONCE(), so we add "Fre Once".
+The full string is thus:
+
+	Rfi Once PodRR Once Fre Once Rfi Once PodRR Once Fre Once
+
+This string can be given to the "norm7" and "classify7" tools to
+produce the name:
+
+	$ norm7 -bell linux-kernel.bell \
+		Rfi Once PodRR Once Fre Once Rfi Once PodRR Once Fre Once | \
+	  sed -e 's/:.*//g'
+	SB+rfionceonce-poonceonces
+
+Adding the ".litmus" suffix: SB+rfionceonce-poonceonces.litmus
+
+The descriptors that describe connections between consecutive accesses
+within the cycle through a given litmus test can be provided by the herd
+tool (Rfi, Po, Fre, and so on) or by the linux-kernel.bell file (Once,
+Release, Acquire, and so on).
+
+To see the full list of descriptors, execute the following command:
+
+	$ diyone7 -bell linux-kernel.bell -show edges
diff --git a/tools/memory-model/litmus-tests/S+wmbonceonce+poacquireonce.litmus b/tools/memory-model/litmus-tests/S+fencewmbonceonce+poacquireonce.litmus
index c53350205d28..18479823cd6c 100644
--- a/tools/memory-model/litmus-tests/S+wmbonceonce+poacquireonce.litmus
+++ b/tools/memory-model/litmus-tests/S+fencewmbonceonce+poacquireonce.litmus
@@ -1,4 +1,4 @@
-C S+wmbonceonce+poacquireonce
+C S+fencewmbonceonce+poacquireonce
 
 (*
  * Result: Never
diff --git a/tools/memory-model/litmus-tests/SB+mbonceonces.litmus b/tools/memory-model/litmus-tests/SB+fencembonceonces.litmus
index 74b874ffa8da..ed5fff18d223 100644
--- a/tools/memory-model/litmus-tests/SB+mbonceonces.litmus
+++ b/tools/memory-model/litmus-tests/SB+fencembonceonces.litmus
@@ -1,4 +1,4 @@
-C SB+mbonceonces
+C SB+fencembonceonces
 
 (*
  * Result: Never
diff --git a/tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus b/tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus
new file mode 100644
index 000000000000..04a16603660b
--- /dev/null
+++ b/tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus
@@ -0,0 +1,32 @@
+C SB+rfionceonce-poonceonces
+
+(*
+ * Result: Sometimes
+ *
+ * This litmus test demonstrates that LKMM is not fully multicopy atomic.
+ *)
+
+{}
+
+P0(int *x, int *y)
+{
+	int r1;
+	int r2;
+
+	WRITE_ONCE(*x, 1);
+	r1 = READ_ONCE(*x);
+	r2 = READ_ONCE(*y);
+}
+
+P1(int *x, int *y)
+{
+	int r3;
+	int r4;
+
+	WRITE_ONCE(*y, 1);
+	r3 = READ_ONCE(*y);
+	r4 = READ_ONCE(*x);
+}
+
+locations [0:r1; 1:r3; x; y] (* Debug aid: Print things not in "exists". *)
+exists (0:r2=0 /\ 1:r4=0)
diff --git a/tools/memory-model/litmus-tests/WRC+pooncerelease+rmbonceonce+Once.litmus b/tools/memory-model/litmus-tests/WRC+pooncerelease+fencermbonceonce+Once.litmus
index ad3448b941e6..e9947250d7de 100644
--- a/tools/memory-model/litmus-tests/WRC+pooncerelease+rmbonceonce+Once.litmus
+++ b/tools/memory-model/litmus-tests/WRC+pooncerelease+fencermbonceonce+Once.litmus
@@ -1,4 +1,4 @@
-C WRC+pooncerelease+rmbonceonce+Once
+C WRC+pooncerelease+fencermbonceonce+Once
 
 (*
  * Result: Never
diff --git a/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+mbonceonce.litmus b/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus
index a20fc3fafb53..88e70b87a683 100644
--- a/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+mbonceonce.litmus
+++ b/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus
@@ -1,4 +1,4 @@
-C Z6.0+pooncerelease+poacquirerelease+mbonceonce
+C Z6.0+pooncerelease+poacquirerelease+fencembonceonce
 
 (*
  * Result: Sometimes