[PATCH memory-model 0/7] LKMM updates for v6.12

[PATCH memory-model 0/7] LKMM updates for v6.12

[Paul E. McKenney]

Hello!

This series adds a few atomic operations, some documentation, and updates
the MAINTAINERS file.

1.	Add atomic_and()/or()/xor() and add_negative, courtesy of
	Puranjay Mohan.

2.	Add atomic_andnot() with its variants, courtesy of Puranjay Mohan.

3.	Document herd7 (abstract) representation, courtesy of Andrea
	Parri.

4.	Add locking.txt and glossary.txt to README, courtesy of Akira
	Yokosawa.

5.	simple.txt: Fix stale reference to recipes-pairs.txt, courtesy
	of Akira Yokosawa.

6.	docs/memory-barriers.txt: Remove left-over references to "CACHE
	COHERENCY", courtesy of Akira Yokosawa.

7.	MAINTAINERS: Add the dedicated maillist info for LKMM, courtesy
	of Boqun Feng.

						Thanx, Paul

------------------------------------------------------------------------

 b/Documentation/memory-barriers.txt                        |    3 
 b/MAINTAINERS                                              |    1 
 b/tools/memory-model/Documentation/README                  |    7 
 b/tools/memory-model/Documentation/herd-representation.txt |  110 +++++++++++++
 b/tools/memory-model/Documentation/simple.txt              |    2 
 b/tools/memory-model/linux-kernel.def                      |   21 ++
 tools/memory-model/Documentation/README                    |   17 ++
 tools/memory-model/linux-kernel.def                        |    6 
 8 files changed, 162 insertions(+), 5 deletions(-)

[PATCH memory-model 1/7] tools/memory-model: Add atomic_and()/or()/xor() and add_negative

[Paul E. McKenney]

From: Puranjay Mohan <puranjay@kernel.org>

Pull-849[1] added the support of '&', '|', and '^' to the herd7 tool's
atomics operations.

Use these in linux-kernel.def to implement atomic_and()/or()/xor() with
all their ordering variants.

atomic_add_negative() is already available so add its acquire, release,
and relaxed ordering variants.

[1] https://github.com/herd/herdtools7/pull/849

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jade Alglave <j.alglave@ucl.ac.uk>
Cc: Luc Maranget <luc.maranget@inria.fr>
Cc: Akira Yokosawa <akiyks@gmail.com>
Cc: Daniel Lustig <dlustig@nvidia.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: <linux-arch@vger.kernel.org>
---
 tools/memory-model/linux-kernel.def | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/tools/memory-model/linux-kernel.def b/tools/memory-model/linux-kernel.def
index 88a39601f5256..d1f11930ec512 100644
--- a/tools/memory-model/linux-kernel.def
+++ b/tools/memory-model/linux-kernel.def
@@ -65,6 +65,9 @@ atomic_set_release(X,V) { smp_store_release(X,V); }
 
 atomic_add(V,X) { __atomic_op(X,+,V); }
 atomic_sub(V,X) { __atomic_op(X,-,V); }
+atomic_and(V,X) { __atomic_op(X,&,V); }
+atomic_or(V,X)  { __atomic_op(X,|,V); }
+atomic_xor(V,X) { __atomic_op(X,^,V); }
 atomic_inc(X)   { __atomic_op(X,+,1); }
 atomic_dec(X)   { __atomic_op(X,-,1); }
 
@@ -77,6 +80,21 @@ atomic_fetch_add_relaxed(V,X) __atomic_fetch_op{once}(X,+,V)
 atomic_fetch_add_acquire(V,X) __atomic_fetch_op{acquire}(X,+,V)
 atomic_fetch_add_release(V,X) __atomic_fetch_op{release}(X,+,V)
 
+atomic_fetch_and(V,X) __atomic_fetch_op{mb}(X,&,V)
+atomic_fetch_and_relaxed(V,X) __atomic_fetch_op{once}(X,&,V)
+atomic_fetch_and_acquire(V,X) __atomic_fetch_op{acquire}(X,&,V)
+atomic_fetch_and_release(V,X) __atomic_fetch_op{release}(X,&,V)
+
+atomic_fetch_or(V,X) __atomic_fetch_op{mb}(X,|,V)
+atomic_fetch_or_relaxed(V,X) __atomic_fetch_op{once}(X,|,V)
+atomic_fetch_or_acquire(V,X) __atomic_fetch_op{acquire}(X,|,V)
+atomic_fetch_or_release(V,X) __atomic_fetch_op{release}(X,|,V)
+
+atomic_fetch_xor(V,X) __atomic_fetch_op{mb}(X,^,V)
+atomic_fetch_xor_relaxed(V,X) __atomic_fetch_op{once}(X,^,V)
+atomic_fetch_xor_acquire(V,X) __atomic_fetch_op{acquire}(X,^,V)
+atomic_fetch_xor_release(V,X) __atomic_fetch_op{release}(X,^,V)
+
 atomic_inc_return(X) __atomic_op_return{mb}(X,+,1)
 atomic_inc_return_relaxed(X) __atomic_op_return{once}(X,+,1)
 atomic_inc_return_acquire(X) __atomic_op_return{acquire}(X,+,1)
@@ -117,3 +135,6 @@ atomic_sub_and_test(V,X) __atomic_op_return{mb}(X,-,V) == 0
 atomic_dec_and_test(X)  __atomic_op_return{mb}(X,-,1) == 0
 atomic_inc_and_test(X)  __atomic_op_return{mb}(X,+,1) == 0
 atomic_add_negative(V,X) __atomic_op_return{mb}(X,+,V) < 0
+atomic_add_negative_relaxed(V,X) __atomic_op_return{once}(X,+,V) < 0
+atomic_add_negative_acquire(V,X) __atomic_op_return{acquire}(X,+,V) < 0
+atomic_add_negative_release(V,X) __atomic_op_return{release}(X,+,V) < 0
-- 
2.40.1

[PATCH memory-model 2/7] tools/memory-model: Add atomic_andnot() with its variants

[Paul E. McKenney]

From: Puranjay Mohan <puranjay@kernel.org>

Pull-855[1] added the support of atomic_andnot() to the herd tool. Use
this to add the implementation in the LKMM. All of the ordering variants
are also added.

Here is a small litmus-test that uses this operation:

C andnot

{
atomic_t u = ATOMIC_INIT(7);
}

P0(atomic_t *u)
{

        r0 = atomic_fetch_andnot(3, u);
        r1 = READ_ONCE(*u);
}

exists (0:r0=7 /\ 0:r1=4)

Test andnot Allowed
States 1
0:r0=7; 0:r1=4;
Ok
Witnesses
Positive: 1 Negative: 0
Condition exists (0:r0=7 /\ 0:r1=4)
Observation andnot Always 1 0
Time andnot 0.00
Hash=78f011a0b5a0c65fa1cf106fcd62c845

[1] https://github.com/herd/herdtools7/pull/855

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jade Alglave <j.alglave@ucl.ac.uk>
Cc: Luc Maranget <luc.maranget@inria.fr>
Cc: Akira Yokosawa <akiyks@gmail.com>
Cc: Daniel Lustig <dlustig@nvidia.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: <linux-arch@vger.kernel.org>
---
 tools/memory-model/linux-kernel.def | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/memory-model/linux-kernel.def b/tools/memory-model/linux-kernel.def
index d1f11930ec512..a12b96c547b7a 100644
--- a/tools/memory-model/linux-kernel.def
+++ b/tools/memory-model/linux-kernel.def
@@ -70,6 +70,7 @@ atomic_or(V,X)  { __atomic_op(X,|,V); }
 atomic_xor(V,X) { __atomic_op(X,^,V); }
 atomic_inc(X)   { __atomic_op(X,+,1); }
 atomic_dec(X)   { __atomic_op(X,-,1); }
+atomic_andnot(V,X) { __atomic_op(X,&~,V); }
 
 atomic_add_return(V,X) __atomic_op_return{mb}(X,+,V)
 atomic_add_return_relaxed(V,X) __atomic_op_return{once}(X,+,V)
@@ -138,3 +139,8 @@ atomic_add_negative(V,X) __atomic_op_return{mb}(X,+,V) < 0
 atomic_add_negative_relaxed(V,X) __atomic_op_return{once}(X,+,V) < 0
 atomic_add_negative_acquire(V,X) __atomic_op_return{acquire}(X,+,V) < 0
 atomic_add_negative_release(V,X) __atomic_op_return{release}(X,+,V) < 0
+
+atomic_fetch_andnot(V,X) __atomic_fetch_op{mb}(X,&~,V)
+atomic_fetch_andnot_acquire(V,X) __atomic_fetch_op{acquire}(X,&~,V)
+atomic_fetch_andnot_release(V,X) __atomic_fetch_op{release}(X,&~,V)
+atomic_fetch_andnot_relaxed(V,X) __atomic_fetch_op{once}(X,&~,V)
-- 
2.40.1

[PATCH memory-model 3/7] tools/memory-model: Document herd7 (abstract) representation

[Paul E. McKenney]

From: Andrea Parri <parri.andrea@gmail.com>

The Linux-kernel memory model (LKMM) source code and the herd7 tool are
closely linked in that the latter is responsible for (pre)processing
each C-like macro of a litmus test, and for providing the LKMM with a
set of events, or "representation", corresponding to the given macro.
This commit therefore provides herd-representation.txt to document
the representations of the concurrency macros, following their
"classification" in Documentation/atomic_t.txt.

Link: https://lore.kernel.org/all/ZnFZPJlILp5B9scN@andrea/

Suggested-by: Hernan Ponce de Leon <hernan.poncedeleon@huaweicloud.com>
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Hernan Ponce de Leon <hernan.poncedeleon@huaweicloud.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 tools/memory-model/Documentation/README       |   7 +-
 .../Documentation/herd-representation.txt     | 110 ++++++++++++++++++
 2 files changed, 116 insertions(+), 1 deletion(-)
 create mode 100644 tools/memory-model/Documentation/herd-representation.txt

diff --git a/tools/memory-model/Documentation/README b/tools/memory-model/Documentation/README
index 304162743a5b8..44e7dae73b296 100644
--- a/tools/memory-model/Documentation/README
+++ b/tools/memory-model/Documentation/README
@@ -33,7 +33,8 @@ o	You are familiar with Linux-kernel concurrency and the use of
 
 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
@@ -61,6 +62,10 @@ control-dependencies.txt
 explanation.txt
 	Detailed description of the memory model.
 
+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.
diff --git a/tools/memory-model/Documentation/herd-representation.txt b/tools/memory-model/Documentation/herd-representation.txt
new file mode 100644
index 0000000000000..ed988906f2b71
--- /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                            |
+    ------------------------------------------------------------------------------
-- 
2.40.1

[PATCH memory-model 4/7] tools/memory-model: Add locking.txt and glossary.txt to README

[Paul E. McKenney]

From: Akira Yokosawa <akiyks@gmail.com>

locking.txt and glossary.txt have been in LKMM's documentation for
quite a while.

Add them in README's introduction of docs and the list of docs at the
bottom.  Add access-marking.txt in the former as well.

Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 tools/memory-model/Documentation/README | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/tools/memory-model/Documentation/README b/tools/memory-model/Documentation/README
index 44e7dae73b296..9999c1effdb65 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
@@ -28,6 +33,11 @@ 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
 
@@ -62,6 +72,9 @@ 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.
@@ -70,6 +83,10 @@ 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.
-- 
2.40.1

[PATCH memory-model 5/7] tools/memory-model: simple.txt: Fix stale reference to recipes-pairs.txt

[Paul E. McKenney]

From: Akira Yokosawa <akiyks@gmail.com>

There has never been recipes-paris.txt at least since v5.11.
Fix the typo.

Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 tools/memory-model/Documentation/simple.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/memory-model/Documentation/simple.txt b/tools/memory-model/Documentation/simple.txt
index 4c789ec8334fc..21f06c1d1b70d 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.
-- 
2.40.1

[PATCH memory-model 6/7] docs/memory-barriers.txt: Remove left-over references to "CACHE COHERENCY"

[Paul E. McKenney]

From: Akira Yokosawa <akiyks@gmail.com>

Commit 8ca924aeb4f2 ("Documentation/barriers: Remove references to
[smp_]read_barrier_depends()") removed the entire section of "CACHE
COHERENCY", without getting rid of its traces.

Remove them.

Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
---
 Documentation/memory-barriers.txt | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index 4202174a6262c..93d58d9a428b8 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
 --------------------
-- 
2.40.1

[PATCH memory-model 7/7] MAINTAINERS: Add the dedicated maillist info for LKMM

[Paul E. McKenney]

From: Boqun Feng <boqun.feng@gmail.com>

A dedicated mail list has been created for Linux kernel memory model
discussion, which could help people more easily track memory model
related discussions.  This could also help bring memory model discussions
to a broader audience.  Therefore, add the list information to the LKMM
maintainers entry.

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 MAINTAINERS | 1 +
 1 file changed, 1 insertion(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 42decde383206..0a3a769148fd8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12993,6 +12993,7 @@ 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
-- 
2.40.1

Re: [PATCH memory-model 7/7] MAINTAINERS: Add the dedicated maillist info for LKMM

[Andrea Parri]

On Thu, Aug 01, 2024 at 05:22:15PM -0700, Paul E. McKenney wrote:
> From: Boqun Feng <boqun.feng@gmail.com>
> 
> A dedicated mail list has been created for Linux kernel memory model
> discussion, which could help people more easily track memory model
> related discussions.  This could also help bring memory model discussions
> to a broader audience.  Therefore, add the list information to the LKMM
> maintainers entry.
> 
> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

Acked-by: Andrea Parri <parri.andrea@gmail.com>

  Andrea

Re: [PATCH memory-model 7/7] MAINTAINERS: Add the dedicated maillist info for LKMM

[Paul E. McKenney]

On Fri, Aug 02, 2024 at 11:46:20AM +0200, Andrea Parri wrote:
> On Thu, Aug 01, 2024 at 05:22:15PM -0700, Paul E. McKenney wrote:
> > From: Boqun Feng <boqun.feng@gmail.com>
> > 
> > A dedicated mail list has been created for Linux kernel memory model
> > discussion, which could help people more easily track memory model
> > related discussions.  This could also help bring memory model discussions
> > to a broader audience.  Therefore, add the list information to the LKMM
> > maintainers entry.
> > 
> > Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> 
> Acked-by: Andrea Parri <parri.andrea@gmail.com>

Thank you!  I will apply this on my next rebase.

							Thanx, Paul

[PATCH memory-model 2/7] tools/memory-model: Add atomic_andnot() with its variants

[Paul E. McKenney]

From: Puranjay Mohan <puranjay@kernel.org>

Pull-855[1] added the support of atomic_andnot() to the herd tool. Use
this to add the implementation in the LKMM. All of the ordering variants
are also added.

Here is a small litmus-test that uses this operation:

C andnot

{
atomic_t u = ATOMIC_INIT(7);
}

P0(atomic_t *u)
{

        r0 = atomic_fetch_andnot(3, u);
        r1 = READ_ONCE(*u);
}

exists (0:r0=7 /\ 0:r1=4)

Test andnot Allowed
States 1
0:r0=7; 0:r1=4;
Ok
Witnesses
Positive: 1 Negative: 0
Condition exists (0:r0=7 /\ 0:r1=4)
Observation andnot Always 1 0
Time andnot 0.00
Hash=78f011a0b5a0c65fa1cf106fcd62c845

[1] https://github.com/herd/herdtools7/pull/855

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Will Deacon <will@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Jade Alglave <j.alglave@ucl.ac.uk>
Cc: Luc Maranget <luc.maranget@inria.fr>
Cc: Akira Yokosawa <akiyks@gmail.com>
Cc: Daniel Lustig <dlustig@nvidia.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: <linux-arch@vger.kernel.org>
---
 tools/memory-model/linux-kernel.def | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/memory-model/linux-kernel.def b/tools/memory-model/linux-kernel.def
index d1f11930ec512..a12b96c547b7a 100644
--- a/tools/memory-model/linux-kernel.def
+++ b/tools/memory-model/linux-kernel.def
@@ -70,6 +70,7 @@ atomic_or(V,X)  { __atomic_op(X,|,V); }
 atomic_xor(V,X) { __atomic_op(X,^,V); }
 atomic_inc(X)   { __atomic_op(X,+,1); }
 atomic_dec(X)   { __atomic_op(X,-,1); }
+atomic_andnot(V,X) { __atomic_op(X,&~,V); }
 
 atomic_add_return(V,X) __atomic_op_return{mb}(X,+,V)
 atomic_add_return_relaxed(V,X) __atomic_op_return{once}(X,+,V)
@@ -138,3 +139,8 @@ atomic_add_negative(V,X) __atomic_op_return{mb}(X,+,V) < 0
 atomic_add_negative_relaxed(V,X) __atomic_op_return{once}(X,+,V) < 0
 atomic_add_negative_acquire(V,X) __atomic_op_return{acquire}(X,+,V) < 0
 atomic_add_negative_release(V,X) __atomic_op_return{release}(X,+,V) < 0
+
+atomic_fetch_andnot(V,X) __atomic_fetch_op{mb}(X,&~,V)
+atomic_fetch_andnot_acquire(V,X) __atomic_fetch_op{acquire}(X,&~,V)
+atomic_fetch_andnot_release(V,X) __atomic_fetch_op{release}(X,&~,V)
+atomic_fetch_andnot_relaxed(V,X) __atomic_fetch_op{once}(X,&~,V)
-- 
2.40.1