Merge tag 'lkmm.2024.09.14b' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull memory model doc updates from Paul McKenney:
 "lkmm: Add documentation and mailing list

  This contains documentation updates from Andrea Parri and Akira
  Yokosawa. Also, there is now an lkmm@lists.linux.dev, and Boqun Feng's
  update adds this to the LKMM MAINTAINERS entry.

  Not included are a couple of more commits from Puranjay Mohan adding
  more atomic operations to LKMM, but these await a herdtools7 release
  that includes tool-side support for this functionality. With luck, I
  will send a separate pull request for these later in the merge window"

* tag 'lkmm.2024.09.14b' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  MAINTAINERS: Add the dedicated maillist info for LKMM
  docs/memory-barriers.txt: Remove left-over references to "CACHE COHERENCY"
  tools/memory-model: simple.txt: Fix stale reference to recipes-pairs.txt
  tools/memory-model: Add locking.txt and glossary.txt to README
  tools/memory-model: Document herd7 (abstract) representation

5 files changed, 135 insertions, 5 deletions

diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index 4202174a6262..93d58d9a428b 100644
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -88,7 +88,6 @@ CONTENTS
 
  (*) The effects of the cpu cache.
 
-     - Cache coherency.
      - Cache coherency vs DMA.
      - Cache coherency vs MMIO.
 
@@ -677,8 +676,6 @@ include/linux/rcupdate.h.  This permits the current target of an RCU'd
 pointer to be replaced with a new modified target, without the replacement
 target appearing to be incompletely initialised.
 
-See also the subsection on "Cache Coherency" for a more thorough example.
-
 
 CONTROL DEPENDENCIES
 --------------------
diff --git a/MAINTAINERS b/MAINTAINERS
index 0035cef79ba5..701b426f902d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13068,6 +13068,7 @@ R:	Daniel Lustig <dlustig@nvidia.com>
 R:	Joel Fernandes <joel@joelfernandes.org>
 L:	linux-kernel@vger.kernel.org
 L:	linux-arch@vger.kernel.org
+L:	lkmm@lists.linux.dev
 S:	Supported
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev
 F:	Documentation/atomic_bitops.txt
diff --git a/tools/memory-model/Documentation/README b/tools/memory-model/Documentation/README
index 304162743a5b..9999c1effdb6 100644
--- a/tools/memory-model/Documentation/README
+++ b/tools/memory-model/Documentation/README
@@ -9,6 +9,8 @@ depending on what you know and what you would like to learn.  Please note
 that the documents later in this list assume that the reader understands
 the material provided by documents earlier in this list.
 
+If LKMM-specific terms lost you, glossary.txt might help you.
+
 o	You are new to Linux-kernel concurrency: simple.txt
 
 o	You have some background in Linux-kernel concurrency, and would
@@ -21,6 +23,9 @@ o	You are familiar with the Linux-kernel concurrency primitives
 	that you need, and just want to get started with LKMM litmus
 	tests:  litmus-tests.txt
 
+o	You would like to access lock-protected shared variables without
+	having their corresponding locks held:  locking.txt
+
 o	You are familiar with Linux-kernel concurrency, and would
 	like a detailed intuitive understanding of LKMM, including
 	situations involving more than two threads:  recipes.txt
@@ -28,12 +33,18 @@ o	You are familiar with Linux-kernel concurrency, and would
 o	You would like a detailed understanding of what your compiler can
 	and cannot do to control dependencies:  control-dependencies.txt
 
+o	You would like to mark concurrent normal accesses to shared
+	variables so that intentional "racy" accesses can be properly
+	documented, especially when you are responding to complaints
+	from KCSAN:  access-marking.txt
+
 o	You are familiar with Linux-kernel concurrency and the use of
 	LKMM, and would like a quick reference:  cheatsheet.txt
 
 o	You are familiar with Linux-kernel concurrency and the use
 	of LKMM, and would like to learn about LKMM's requirements,
-	rationale, and implementation:	explanation.txt
+	rationale, and implementation:	explanation.txt and
+	herd-representation.txt
 
 o	You are interested in the publications related to LKMM, including
 	hardware manuals, academic literature, standards-committee
@@ -61,10 +72,21 @@ control-dependencies.txt
 explanation.txt
 	Detailed description of the memory model.
 
+glossary.txt
+	Brief definitions of LKMM-related terms.
+
+herd-representation.txt
+	The (abstract) representation of the Linux-kernel concurrency
+	primitives in terms of events.
+
 litmus-tests.txt
 	The format, features, capabilities, and limitations of the litmus
 	tests that LKMM can evaluate.
 
+locking.txt
+	Rules for accessing lock-protected shared variables outside of
+	their corresponding critical sections.
+
 ordering.txt
 	Overview of the Linux kernel's low-level memory-ordering
 	primitives by category.
diff --git a/tools/memory-model/Documentation/herd-representation.txt b/tools/memory-model/Documentation/herd-representation.txt
new file mode 100644
index 000000000000..ed988906f2b7
--- /dev/null
+++ b/tools/memory-model/Documentation/herd-representation.txt
@@ -0,0 +1,110 @@
+#
+# Legend:
+#	R,	a Load event
+#	W,	a Store event
+#	F,	a Fence event
+#	LKR,	a Lock-Read event
+#	LKW,	a Lock-Write event
+#	UL,	an Unlock event
+#	LF,	a Lock-Fail event
+#	RL,	a Read-Locked event
+#	RU,	a Read-Unlocked event
+#	R*,	a Load event included in RMW
+#	W*,	a Store event included in RMW
+#	SRCU,	a Sleepable-Read-Copy-Update event
+#
+#	po,	a Program-Order link
+#	rmw,	a Read-Modify-Write link - every rmw link is a po link
+#
+# By convention, a blank line in a cell means "same as the preceding line".
+#
+# Disclaimer.  The table includes representations of "add" and "and" operations;
+# corresponding/identical representations of "sub", "inc", "dec" and "or", "xor",
+# "andnot" operations are omitted.
+#
+    ------------------------------------------------------------------------------
+    |                        C macro | Events                                    |
+    ------------------------------------------------------------------------------
+    |                    Non-RMW ops |                                           |
+    ------------------------------------------------------------------------------
+    |                      READ_ONCE | R[once]                                   |
+    |                    atomic_read |                                           |
+    |                     WRITE_ONCE | W[once]                                   |
+    |                     atomic_set |                                           |
+    |               smp_load_acquire | R[acquire]                                |
+    |            atomic_read_acquire |                                           |
+    |              smp_store_release | W[release]                                |
+    |             atomic_set_release |                                           |
+    |                   smp_store_mb | W[once] ->po F[mb]                        |
+    |                         smp_mb | F[mb]                                     |
+    |                        smp_rmb | F[rmb]                                    |
+    |                        smp_wmb | F[wmb]                                    |
+    |          smp_mb__before_atomic | F[before-atomic]                          |
+    |           smp_mb__after_atomic | F[after-atomic]                           |
+    |                    spin_unlock | UL                                        |
+    |                 spin_is_locked | On success: RL                            |
+    |                                | On failure: RU                            |
+    |         smp_mb__after_spinlock | F[after-spinlock]                         |
+    |      smp_mb__after_unlock_lock | F[after-unlock-lock]                      |
+    |                  rcu_read_lock | F[rcu-lock]                               |
+    |                rcu_read_unlock | F[rcu-unlock]                             |
+    |                synchronize_rcu | F[sync-rcu]                               |
+    |                rcu_dereference | R[once]                                   |
+    |             rcu_assign_pointer | W[release]                                |
+    |                 srcu_read_lock | R[srcu-lock]                              |
+    |                 srcu_down_read |                                           |
+    |               srcu_read_unlock | W[srcu-unlock]                            |
+    |                   srcu_up_read |                                           |
+    |               synchronize_srcu | SRCU[sync-srcu]                           |
+    | smp_mb__after_srcu_read_unlock | F[after-srcu-read-unlock]                 |
+    ------------------------------------------------------------------------------
+    |       RMW ops w/o return value |                                           |
+    ------------------------------------------------------------------------------
+    |                     atomic_add | R*[noreturn] ->rmw W*[once]               |
+    |                     atomic_and |                                           |
+    |                      spin_lock | LKR ->po LKW                              |
+    ------------------------------------------------------------------------------
+    |        RMW ops w/ return value |                                           |
+    ------------------------------------------------------------------------------
+    |              atomic_add_return | F[mb] ->po R*[once]                       |
+    |                                |     ->rmw W*[once] ->po F[mb]             |
+    |               atomic_fetch_add |                                           |
+    |               atomic_fetch_and |                                           |
+    |                    atomic_xchg |                                           |
+    |                           xchg |                                           |
+    |            atomic_add_negative |                                           |
+    |      atomic_add_return_relaxed | R*[once] ->rmw W*[once]                   |
+    |       atomic_fetch_add_relaxed |                                           |
+    |       atomic_fetch_and_relaxed |                                           |
+    |            atomic_xchg_relaxed |                                           |
+    |                   xchg_relaxed |                                           |
+    |    atomic_add_negative_relaxed |                                           |
+    |      atomic_add_return_acquire | R*[acquire] ->rmw W*[once]                |
+    |       atomic_fetch_add_acquire |                                           |
+    |       atomic_fetch_and_acquire |                                           |
+    |            atomic_xchg_acquire |                                           |
+    |                   xchg_acquire |                                           |
+    |    atomic_add_negative_acquire |                                           |
+    |      atomic_add_return_release | R*[once] ->rmw W*[release]                |
+    |       atomic_fetch_add_release |                                           |
+    |       atomic_fetch_and_release |                                           |
+    |            atomic_xchg_release |                                           |
+    |                   xchg_release |                                           |
+    |    atomic_add_negative_release |                                           |
+    ------------------------------------------------------------------------------
+    |            Conditional RMW ops |                                           |
+    ------------------------------------------------------------------------------
+    |                 atomic_cmpxchg | On success: F[mb] ->po R*[once]           |
+    |                                |                 ->rmw W*[once] ->po F[mb] |
+    |                                | On failure: R*[once]                      |
+    |                        cmpxchg |                                           |
+    |              atomic_add_unless |                                           |
+    |         atomic_cmpxchg_relaxed | On success: R*[once] ->rmw W*[once]       |
+    |                                | On failure: R*[once]                      |
+    |         atomic_cmpxchg_acquire | On success: R*[acquire] ->rmw W*[once]    |
+    |                                | On failure: R*[once]                      |
+    |         atomic_cmpxchg_release | On success: R*[once] ->rmw W*[release]    |
+    |                                | On failure: R*[once]                      |
+    |                   spin_trylock | On success: LKR ->po LKW                  |
+    |                                | On failure: LF                            |
+    ------------------------------------------------------------------------------
diff --git a/tools/memory-model/Documentation/simple.txt b/tools/memory-model/Documentation/simple.txt
index 4c789ec8334f..21f06c1d1b70 100644
--- a/tools/memory-model/Documentation/simple.txt
+++ b/tools/memory-model/Documentation/simple.txt
@@ -266,5 +266,5 @@ More complex use cases
 ======================
 
 If the alternatives above do not do what you need, please look at the
-recipes-pairs.txt file to peel off the next layer of the memory-ordering
+recipes.txt file to peel off the next layer of the memory-ordering
 onion.