Merge tag 'lkmm.2025.03.21a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull kernel memory model updates from Paul McKenney:
 "Add more atomic operations, rework tags, and update documentation:

   - Add additional atomic operations (Puranjay Mohan)

   - Make better use of herd7 tags (Jonas Oberhauser)

   - Update documentation (Akira Yokosawa)

  These changes require v7.58 of the herd7 and klitmus tools, up from
  v7.52"

* tag 'lkmm.2025.03.21a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  tools/memory-model: glossary.txt: Fix indents
  tools/memory-model/README: Fix typo
  tools/memory-model: Distinguish between syntactic and semantic tags
  tools/memory-model: Switch to softcoded herd7 tags
  tools/memory-model: Define effect of Mb tags on RMWs in tools/...
  tools/memory-model: Define applicable tags on operation in tools/...
  tools/memory-model: Legitimize current use of tags in LKMM macros
  tools/memory-model: Add atomic_andnot() with its variants
  tools/memory-model: Add atomic_and()/or()/xor() and add_negative

1 files changed, 10 insertions, 0 deletions

diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat
index adf3c4f41229..d7e7bf13c831 100644
--- a/tools/memory-model/linux-kernel.cat
+++ b/tools/memory-model/linux-kernel.cat
@@ -34,6 +34,16 @@ let R4rmb = R \ Noreturn	(* Reads for which rmb works *)
 let rmb = [R4rmb] ; fencerel(Rmb) ; [R4rmb]
 let wmb = [W] ; fencerel(Wmb) ; [W]
 let mb = ([M] ; fencerel(Mb) ; [M]) |
+	(*
+	 * full-barrier RMWs (successful cmpxchg(), xchg(), etc.) act as
+	 * though there were enclosed by smp_mb().
+	 * The effect of these virtual smp_mb() is formalized by adding
+	 * Mb tags to the read and write of the operation, and providing
+	 * the same ordering as though there were additional po edges
+	 * between the Mb tag and the read resp. write.
+	 *)
+	([M] ; po ; [Mb & R]) |
+	([Mb & W] ; po ; [M]) |
 	([M] ; fencerel(Before-atomic) ; [RMW] ; po? ; [M]) |
 	([M] ; po? ; [RMW] ; fencerel(After-atomic) ; [M]) |
 	([M] ; po? ; [LKW] ; fencerel(After-spinlock) ; [M]) |