Merge branch 'for-mingo-lkmm' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into locking/core

Pull LKMM updates from Paul E. McKenney.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

34 files changed, 42 insertions, 138 deletions

diff --git a/tools/memory-model/Documentation/glossary.txt b/tools/memory-model/Documentation/glossary.txt
index 79acb75d56ea..b2da6365be63 100644
--- a/tools/memory-model/Documentation/glossary.txt
+++ b/tools/memory-model/Documentation/glossary.txt
@@ -33,10 +33,11 @@ Acquire:  With respect to a lock, acquiring that lock, for example,
 	acquire loads.
 
 	When an acquire load returns the value stored by a release store
-	to that same variable, then all operations preceding that store
-	happen before any operations following that load acquire.
+	to that same variable, (in other words, the acquire load "reads
+	from" the release store), then all operations preceding that
+	store "happen before" any operations following that load acquire.
 
-	See also "Relaxed" and "Release".
+	See also "Happens-Before", "Reads-From", "Relaxed", and "Release".
 
 Coherence (co):  When one CPU's store to a given variable overwrites
 	either the value from another CPU's store or some later value,
@@ -119,6 +120,11 @@ Fully Ordered:  An operation such as smp_mb() that orders all of
 	that orders all of its CPU's prior accesses, itself, and
 	all of its CPU's subsequent accesses.
 
+Happens-Before (hb): A relation between two accesses in which LKMM
+	guarantees the first access precedes the second.  For more
+	detail, please see the "THE HAPPENS-BEFORE RELATION: hb"
+	section of explanation.txt.
+
 Marked Access:  An access to a variable that uses an special function or
 	macro such as "r1 = READ_ONCE(x)" or "smp_store_release(&a, 1)".
 
diff --git a/tools/memory-model/README b/tools/memory-model/README
index 39d08d1f0443..9a84c45504ab 100644
--- a/tools/memory-model/README
+++ b/tools/memory-model/README
@@ -51,7 +51,7 @@ klitmus7 Compatibility Table
 	============  ==========
 	target Linux  herdtools7
 	------------  ----------
-	     -- 4.18  7.48 --
+	     -- 4.14  7.48 --
 	4.15 -- 4.19  7.49 --
 	4.20 -- 5.5   7.54 --
 	5.6  --       7.56 --
diff --git a/tools/memory-model/litmus-tests/CoRR+poonceonce+Once.litmus b/tools/memory-model/litmus-tests/CoRR+poonceonce+Once.litmus
index 772544f03fb5..967f9f2a6226 100644
--- a/tools/memory-model/litmus-tests/CoRR+poonceonce+Once.litmus
+++ b/tools/memory-model/litmus-tests/CoRR+poonceonce+Once.litmus
@@ -7,9 +7,7 @@ C CoRR+poonceonce+Once
  * reads from the same variable are ordered.
  *)
 
-{
-	int x;
-}
+{}
 
 P0(int *x)
 {
diff --git a/tools/memory-model/litmus-tests/CoRW+poonceonce+Once.litmus b/tools/memory-model/litmus-tests/CoRW+poonceonce+Once.litmus
index 5faae98f7ffb..4635739f3974 100644
--- a/tools/memory-model/litmus-tests/CoRW+poonceonce+Once.litmus
+++ b/tools/memory-model/litmus-tests/CoRW+poonceonce+Once.litmus
@@ -7,9 +7,7 @@ C CoRW+poonceonce+Once
  * a given variable and a later write to that same variable are ordered.
  *)
 
-{
-	int x;
-}
+{}
 
 P0(int *x)
 {
diff --git a/tools/memory-model/litmus-tests/CoWR+poonceonce+Once.litmus b/tools/memory-model/litmus-tests/CoWR+poonceonce+Once.litmus
index 77c9cc9f8dc6..bb068c92d8da 100644
--- a/tools/memory-model/litmus-tests/CoWR+poonceonce+Once.litmus
+++ b/tools/memory-model/litmus-tests/CoWR+poonceonce+Once.litmus
@@ -7,9 +7,7 @@ C CoWR+poonceonce+Once
  * given variable and a later read from that same variable are ordered.
  *)
 
-{
-	int x;
-}
+{}
 
 P0(int *x)
 {
diff --git a/tools/memory-model/litmus-tests/CoWW+poonceonce.litmus b/tools/memory-model/litmus-tests/CoWW+poonceonce.litmus
index 85ef746f511a..0d9f0a958799 100644
--- a/tools/memory-model/litmus-tests/CoWW+poonceonce.litmus
+++ b/tools/memory-model/litmus-tests/CoWW+poonceonce.litmus
@@ -7,9 +7,7 @@ C CoWW+poonceonce
  * writes to the same variable are ordered.
  *)
 
-{
-	int x;
-}
+{}
 
 P0(int *x)
 {
diff --git a/tools/memory-model/litmus-tests/IRIW+fencembonceonces+OnceOnce.litmus b/tools/memory-model/litmus-tests/IRIW+fencembonceonces+OnceOnce.litmus
index 87aa900125ab..e729d2776e89 100644
--- a/tools/memory-model/litmus-tests/IRIW+fencembonceonces+OnceOnce.litmus
+++ b/tools/memory-model/litmus-tests/IRIW+fencembonceonces+OnceOnce.litmus
@@ -10,10 +10,7 @@ C IRIW+fencembonceonces+OnceOnce
  * process?  This litmus test exercises LKMM's "propagation" rule.
  *)
 
-{
-	int x;
-	int y;
-}
+{}
 
 P0(int *x)
 {
diff --git a/tools/memory-model/litmus-tests/IRIW+poonceonces+OnceOnce.litmus b/tools/memory-model/litmus-tests/IRIW+poonceonces+OnceOnce.litmus
index f84022dca555..4b54dd6a6cd9 100644
--- a/tools/memory-model/litmus-tests/IRIW+poonceonces+OnceOnce.litmus
+++ b/tools/memory-model/litmus-tests/IRIW+poonceonces+OnceOnce.litmus
@@ -10,10 +10,7 @@ C IRIW+poonceonces+OnceOnce
  * different process?
  *)
 
-{
-	int x;
-	int y;
-}
+{}
 
 P0(int *x)
 {
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 398f624daa77..094d58df7789 100644
--- a/tools/memory-model/litmus-tests/ISA2+pooncelock+pooncelock+pombonce.litmus
+++ b/tools/memory-model/litmus-tests/ISA2+pooncelock+pooncelock+pombonce.litmus
@@ -7,12 +7,7 @@ C ISA2+pooncelock+pooncelock+pombonce
  * (in P0() and P1()) is visible to external process P2().
  *)
 
-{
-	spinlock_t mylock;
-	int x;
-	int y;
-	int z;
-}
+{}
 
 P0(int *x, int *y, spinlock_t *mylock)
 {
diff --git a/tools/memory-model/litmus-tests/ISA2+poonceonces.litmus b/tools/memory-model/litmus-tests/ISA2+poonceonces.litmus
index 212a432ba16b..b321aa6f4ea5 100644
--- a/tools/memory-model/litmus-tests/ISA2+poonceonces.litmus
+++ b/tools/memory-model/litmus-tests/ISA2+poonceonces.litmus
@@ -9,11 +9,7 @@ C ISA2+poonceonces
  * of the smp_load_acquire() invocations are replaced by READ_ONCE()?
  *)
 
-{
-	int x;
-	int y;
-	int z;
-}
+{}
 
 P0(int *x, int *y)
 {
diff --git a/tools/memory-model/litmus-tests/ISA2+pooncerelease+poacquirerelease+poacquireonce.litmus b/tools/memory-model/litmus-tests/ISA2+pooncerelease+poacquirerelease+poacquireonce.litmus
index 7afd85672ccd..025b0462ec9b 100644
--- a/tools/memory-model/litmus-tests/ISA2+pooncerelease+poacquirerelease+poacquireonce.litmus
+++ b/tools/memory-model/litmus-tests/ISA2+pooncerelease+poacquirerelease+poacquireonce.litmus
@@ -11,11 +11,7 @@ C ISA2+pooncerelease+poacquirerelease+poacquireonce
  * (AKA non-rf) link, so release-acquire is all that is needed.
  *)
 
-{
-	int x;
-	int y;
-	int z;
-}
+{}
 
 P0(int *x, int *y)
 {
diff --git a/tools/memory-model/litmus-tests/LB+fencembonceonce+ctrlonceonce.litmus b/tools/memory-model/litmus-tests/LB+fencembonceonce+ctrlonceonce.litmus
index c8a93c7ee556..4727f5aaf03b 100644
--- a/tools/memory-model/litmus-tests/LB+fencembonceonce+ctrlonceonce.litmus
+++ b/tools/memory-model/litmus-tests/LB+fencembonceonce+ctrlonceonce.litmus
@@ -11,10 +11,7 @@ C LB+fencembonceonce+ctrlonceonce
  * another control dependency and order would still be maintained.)
  *)
 
-{
-	int x;
-	int y;
-}
+{}
 
 P0(int *x, int *y)
 {
diff --git a/tools/memory-model/litmus-tests/LB+poacquireonce+pooncerelease.litmus b/tools/memory-model/litmus-tests/LB+poacquireonce+pooncerelease.litmus
index 2fa029568fa1..07b9904b0e49 100644
--- a/tools/memory-model/litmus-tests/LB+poacquireonce+pooncerelease.litmus
+++ b/tools/memory-model/litmus-tests/LB+poacquireonce+pooncerelease.litmus
@@ -8,10 +8,7 @@ C LB+poacquireonce+pooncerelease
  * to the other?
  *)
 
-{
-	int x;
-	int y;
-}
+{}
 
 P0(int *x, int *y)
 {
diff --git a/tools/memory-model/litmus-tests/LB+poonceonces.litmus b/tools/memory-model/litmus-tests/LB+poonceonces.litmus
index 2107306e8625..74c49cb3c37b 100644
--- a/tools/memory-model/litmus-tests/LB+poonceonces.litmus
+++ b/tools/memory-model/litmus-tests/LB+poonceonces.litmus
@@ -7,10 +7,7 @@ C LB+poonceonces
  * be prevented even with no explicit ordering?
  *)
 
-{
-	int x;
-	int y;
-}
+{}
 
 P0(int *x, int *y)
 {
diff --git a/tools/memory-model/litmus-tests/MP+fencewmbonceonce+fencermbonceonce.litmus b/tools/memory-model/litmus-tests/MP+fencewmbonceonce+fencermbonceonce.litmus
index c5c168d92973..f8ca1229857a 100644
--- a/tools/memory-model/litmus-tests/MP+fencewmbonceonce+fencermbonceonce.litmus
+++ b/tools/memory-model/litmus-tests/MP+fencewmbonceonce+fencermbonceonce.litmus
@@ -8,10 +8,7 @@ C MP+fencewmbonceonce+fencermbonceonce
  * is usually better to use smp_store_release() and smp_load_acquire().
  *)
 
-{
-	int buf;
-	int flag;
-}
+{}
 
 P0(int *buf, int *flag) // Producer
 {
diff --git a/tools/memory-model/litmus-tests/MP+onceassign+derefonce.litmus b/tools/memory-model/litmus-tests/MP+onceassign+derefonce.litmus
index 20ff62649f1e..d84160b9c1ae 100644
--- a/tools/memory-model/litmus-tests/MP+onceassign+derefonce.litmus
+++ b/tools/memory-model/litmus-tests/MP+onceassign+derefonce.litmus
@@ -10,9 +10,7 @@ C MP+onceassign+derefonce
  *)
 
 {
-	int *p=y;
-	int x;
-	int y=0;
+p=y;
 }
 
 P0(int *x, int **p) // Producer
diff --git a/tools/memory-model/litmus-tests/MP+polockmbonce+poacquiresilsil.litmus b/tools/memory-model/litmus-tests/MP+polockmbonce+poacquiresilsil.litmus
index 153917ad5dc9..ba91cc63e148 100644
--- a/tools/memory-model/litmus-tests/MP+polockmbonce+poacquiresilsil.litmus
+++ b/tools/memory-model/litmus-tests/MP+polockmbonce+poacquiresilsil.litmus
@@ -10,10 +10,7 @@ C MP+polockmbonce+poacquiresilsil
  * executed before the lock was acquired (loosely speaking).
  *)
 
-{
-	spinlock_t lo;
-	int x;
-}
+{}
 
 P0(spinlock_t *lo, int *x) // Producer
 {
diff --git a/tools/memory-model/litmus-tests/MP+polockonce+poacquiresilsil.litmus b/tools/memory-model/litmus-tests/MP+polockonce+poacquiresilsil.litmus
index aad64397bb8c..a5ea3ed8f52e 100644
--- a/tools/memory-model/litmus-tests/MP+polockonce+poacquiresilsil.litmus
+++ b/tools/memory-model/litmus-tests/MP+polockonce+poacquiresilsil.litmus
@@ -10,10 +10,7 @@ C MP+polockonce+poacquiresilsil
  * speaking).
  *)
 
-{
-	spinlock_t lo;
-	int x;
-}
+{}
 
 P0(spinlock_t *lo, int *x) // Producer
 {
diff --git a/tools/memory-model/litmus-tests/MP+polocks.litmus b/tools/memory-model/litmus-tests/MP+polocks.litmus
index 21cbca6f3be4..e6af05f70069 100644
--- a/tools/memory-model/litmus-tests/MP+polocks.litmus
+++ b/tools/memory-model/litmus-tests/MP+polocks.litmus
@@ -11,11 +11,7 @@ C MP+polocks
  * to see all prior accesses by those other CPUs.
  *)
 
-{
-	spinlock_t mylock;
-	int buf;
-	int flag;
-}
+{}
 
 P0(int *buf, int *flag, spinlock_t *mylock) // Producer
 {
diff --git a/tools/memory-model/litmus-tests/MP+poonceonces.litmus b/tools/memory-model/litmus-tests/MP+poonceonces.litmus
index 9f9769d647c7..ba9c99c6cf65 100644
--- a/tools/memory-model/litmus-tests/MP+poonceonces.litmus
+++ b/tools/memory-model/litmus-tests/MP+poonceonces.litmus
@@ -7,10 +7,7 @@ C MP+poonceonces
  * no ordering at all?
  *)
 
-{
-	int buf;
-	int flag;
-}
+{}
 
 P0(int *buf, int *flag) // Producer
 {
diff --git a/tools/memory-model/litmus-tests/MP+pooncerelease+poacquireonce.litmus b/tools/memory-model/litmus-tests/MP+pooncerelease+poacquireonce.litmus
index cbe28e733443..f174bfe61702 100644
--- a/tools/memory-model/litmus-tests/MP+pooncerelease+poacquireonce.litmus
+++ b/tools/memory-model/litmus-tests/MP+pooncerelease+poacquireonce.litmus
@@ -8,10 +8,7 @@ C MP+pooncerelease+poacquireonce
  * pattern.
  *)
 
-{
-	int buf;
-	int flag;
-}
+{}
 
 P0(int *buf, int *flag) // Producer
 {
diff --git a/tools/memory-model/litmus-tests/MP+porevlocks.litmus b/tools/memory-model/litmus-tests/MP+porevlocks.litmus
index 012041bd4feb..b9599141160e 100644
--- a/tools/memory-model/litmus-tests/MP+porevlocks.litmus
+++ b/tools/memory-model/litmus-tests/MP+porevlocks.litmus
@@ -11,11 +11,7 @@ C MP+porevlocks
  * see all prior accesses by those other CPUs.
  *)
 
-{
-	spinlock_t mylock;
-	int buf;
-	int flag;
-}
+{}
 
 P0(int *buf, int *flag, spinlock_t *mylock) // Consumer
 {
diff --git a/tools/memory-model/litmus-tests/R+fencembonceonces.litmus b/tools/memory-model/litmus-tests/R+fencembonceonces.litmus
index af9463b39b4a..222a0b850b4a 100644
--- a/tools/memory-model/litmus-tests/R+fencembonceonces.litmus
+++ b/tools/memory-model/litmus-tests/R+fencembonceonces.litmus
@@ -9,10 +9,7 @@ C R+fencembonceonces
  * cause the resulting test to be allowed.
  *)
 
-{
-	int x;
-	int y;
-}
+{}
 
 P0(int *x, int *y)
 {
diff --git a/tools/memory-model/litmus-tests/R+poonceonces.litmus b/tools/memory-model/litmus-tests/R+poonceonces.litmus
index bcd5574e304a..5386f128a131 100644
--- a/tools/memory-model/litmus-tests/R+poonceonces.litmus
+++ b/tools/memory-model/litmus-tests/R+poonceonces.litmus
@@ -8,10 +8,7 @@ C R+poonceonces
  * store propagation delays.
  *)
 
-{
-	int x;
-	int y;
-}
+{}
 
 P0(int *x, int *y)
 {
diff --git a/tools/memory-model/litmus-tests/S+fencewmbonceonce+poacquireonce.litmus b/tools/memory-model/litmus-tests/S+fencewmbonceonce+poacquireonce.litmus
index c36341d1aed6..18479823cd6c 100644
--- a/tools/memory-model/litmus-tests/S+fencewmbonceonce+poacquireonce.litmus
+++ b/tools/memory-model/litmus-tests/S+fencewmbonceonce+poacquireonce.litmus
@@ -7,10 +7,7 @@ C S+fencewmbonceonce+poacquireonce
  * store against a subsequent store?
  *)
 
-{
-	int x;
-	int y;
-}
+{}
 
 P0(int *x, int *y)
 {
diff --git a/tools/memory-model/litmus-tests/S+poonceonces.litmus b/tools/memory-model/litmus-tests/S+poonceonces.litmus
index 7775c23143a0..8c9c2f81a580 100644
--- a/tools/memory-model/litmus-tests/S+poonceonces.litmus
+++ b/tools/memory-model/litmus-tests/S+poonceonces.litmus
@@ -9,10 +9,7 @@ C S+poonceonces
  * READ_ONCE(), is ordering preserved?
  *)
 
-{
-	int x;
-	int y;
-}
+{}
 
 P0(int *x, int *y)
 {
diff --git a/tools/memory-model/litmus-tests/SB+fencembonceonces.litmus b/tools/memory-model/litmus-tests/SB+fencembonceonces.litmus
index 833cdfeb7c09..ed5fff18d223 100644
--- a/tools/memory-model/litmus-tests/SB+fencembonceonces.litmus
+++ b/tools/memory-model/litmus-tests/SB+fencembonceonces.litmus
@@ -9,10 +9,7 @@ C SB+fencembonceonces
  * suffice, but not much else.)
  *)
 
-{
-	int x;
-	int y;
-}
+{}
 
 P0(int *x, int *y)
 {
diff --git a/tools/memory-model/litmus-tests/SB+poonceonces.litmus b/tools/memory-model/litmus-tests/SB+poonceonces.litmus
index c92211ecbfdf..10d550730b25 100644
--- a/tools/memory-model/litmus-tests/SB+poonceonces.litmus
+++ b/tools/memory-model/litmus-tests/SB+poonceonces.litmus
@@ -8,10 +8,7 @@ C SB+poonceonces
  * variable that the preceding process reads.
  *)
 
-{
-	int x;
-	int y;
-}
+{}
 
 P0(int *x, int *y)
 {
diff --git a/tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus b/tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus
index 84344b455eb7..04a16603660b 100644
--- a/tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus
+++ b/tools/memory-model/litmus-tests/SB+rfionceonce-poonceonces.litmus
@@ -6,10 +6,7 @@ C SB+rfionceonce-poonceonces
  * This litmus test demonstrates that LKMM is not fully multicopy atomic.
  *)
 
-{
-	int x;
-	int y;
-}
+{}
 
 P0(int *x, int *y)
 {
diff --git a/tools/memory-model/litmus-tests/WRC+poonceonces+Once.litmus b/tools/memory-model/litmus-tests/WRC+poonceonces+Once.litmus
index 431494708611..6a2bc12a1af1 100644
--- a/tools/memory-model/litmus-tests/WRC+poonceonces+Once.litmus
+++ b/tools/memory-model/litmus-tests/WRC+poonceonces+Once.litmus
@@ -8,10 +8,7 @@ C WRC+poonceonces+Once
  * test has no ordering at all.
  *)
 
-{
-	int x;
-	int y;
-}
+{}
 
 P0(int *x)
 {
diff --git a/tools/memory-model/litmus-tests/WRC+pooncerelease+fencermbonceonce+Once.litmus b/tools/memory-model/litmus-tests/WRC+pooncerelease+fencermbonceonce+Once.litmus
index 554999c64db5..e9947250d7de 100644
--- a/tools/memory-model/litmus-tests/WRC+pooncerelease+fencermbonceonce+Once.litmus
+++ b/tools/memory-model/litmus-tests/WRC+pooncerelease+fencermbonceonce+Once.litmus
@@ -10,10 +10,7 @@ C WRC+pooncerelease+fencermbonceonce+Once
  * is A-cumulative in LKMM.
  *)
 
-{
-	int x;
-	int y;
-}
+{}
 
 P0(int *x)
 {
diff --git a/tools/memory-model/litmus-tests/Z6.0+pooncelock+poonceLock+pombonce.litmus b/tools/memory-model/litmus-tests/Z6.0+pooncelock+poonceLock+pombonce.litmus
index 265a95ffef13..415248fb6699 100644
--- a/tools/memory-model/litmus-tests/Z6.0+pooncelock+poonceLock+pombonce.litmus
+++ b/tools/memory-model/litmus-tests/Z6.0+pooncelock+poonceLock+pombonce.litmus
@@ -9,12 +9,7 @@ C Z6.0+pooncelock+poonceLock+pombonce
  * by CPUs not holding that lock.
  *)
 
-{
-	spinlock_t mylock;
-	int x;
-	int y;
-	int z;
-}
+{}
 
 P0(int *x, int *y, spinlock_t *mylock)
 {
diff --git a/tools/memory-model/litmus-tests/Z6.0+pooncelock+pooncelock+pombonce.litmus b/tools/memory-model/litmus-tests/Z6.0+pooncelock+pooncelock+pombonce.litmus
index 0c9aea8e80df..10a2aa04cd07 100644
--- a/tools/memory-model/litmus-tests/Z6.0+pooncelock+pooncelock+pombonce.litmus
+++ b/tools/memory-model/litmus-tests/Z6.0+pooncelock+pooncelock+pombonce.litmus
@@ -8,12 +8,7 @@ C Z6.0+pooncelock+pooncelock+pombonce
  * seen as ordered by a third process not holding that lock.
  *)
 
-{
-	spinlock_t mylock;
-	int x;
-	int y;
-	int z;
-}
+{}
 
 P0(int *x, int *y, spinlock_t *mylock)
 {
diff --git a/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus b/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus
index 661f9aaa5791..88e70b87a683 100644
--- a/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus
+++ b/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus
@@ -14,11 +14,7 @@ C Z6.0+pooncerelease+poacquirerelease+fencembonceonce
  * involving locking.)
  *)
 
-{
-	int x;
-	int y;
-	int z;
-}
+{}
 
 P0(int *x, int *y)
 {