Merge tag 'locking-core-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "Mutexes:

   - Add killable flavor to guard definitions (Davidlohr Bueso)

   - Remove the list_head from struct mutex (Matthew Wilcox)

   - Rename mutex_init_lockep() (Davidlohr Bueso)

  rwsems:

   - Remove the list_head from struct rw_semaphore and
     replace it with a single pointer (Matthew Wilcox)

   - Fix logic error in rwsem_del_waiter() (Andrei Vagin)

  Semaphores:

   - Remove the list_head from struct semaphore (Matthew Wilcox)

  Jump labels:

   - Use ATOMIC_INIT() for initialization of .enabled (Thomas Weißschuh)

   - Remove workaround for old compilers in initializations
     (Thomas Weißschuh)

  Lock context analysis changes and improvements:

   - Add context analysis for rwsems (Peter Zijlstra)

   - Fix rwlock and spinlock lock context annotations (Bart Van Assche)

   - Fix rwlock support in <linux/spinlock_up.h> (Bart Van Assche)

   - Add lock context annotations in the spinlock implementation
     (Bart Van Assche)

   - signal: Fix the lock_task_sighand() annotation (Bart Van Assche)

   - ww-mutex: Fix the ww_acquire_ctx function annotations
     (Bart Van Assche)

   - Add lock context support in do_raw_{read,write}_trylock()
     (Bart Van Assche)

   - arm64, compiler-context-analysis: Permit alias analysis through
     __READ_ONCE() with CONFIG_LTO=y (Marco Elver)

   - Add __cond_releases() (Peter Zijlstra)

   - Add context analysis for mutexes (Peter Zijlstra)

   - Add context analysis for rtmutexes (Peter Zijlstra)

   - Convert futexes to compiler context analysis (Peter Zijlstra)

  Rust integration updates:

   - Add atomic fetch_sub() implementation (Andreas Hindborg)

   - Refactor various rust_helper_ methods for expansion (Boqun Feng)

   - Add Atomic<*{mut,const} T> support (Boqun Feng)

   - Add atomic operation helpers over raw pointers (Boqun Feng)

   - Add performance-optimal Flag type for atomic booleans, to avoid
     slow byte-sized RMWs on architectures that don't support them.
     (FUJITA Tomonori)

   - Misc cleanups and fixes (Andreas Hindborg, Boqun Feng, FUJITA
     Tomonori)

  LTO support updates:

   - arm64: Optimize __READ_ONCE() with CONFIG_LTO=y (Marco Elver)

   - compiler: Simplify generic RELOC_HIDE() (Marco Elver)

  Miscellaneous fixes and cleanups by Peter Zijlstra, Randy Dunlap,
  Thomas Weißschuh, Davidlohr Bueso and Mikhail Gavrilov"

* tag 'locking-core-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
  compiler: Simplify generic RELOC_HIDE()
  locking: Add lock context annotations in the spinlock implementation
  locking: Add lock context support in do_raw_{read,write}_trylock()
  locking: Fix rwlock support in <linux/spinlock_up.h>
  lockdep: Raise default stack trace limits when KASAN is enabled
  cleanup: Optimize guards
  jump_label: remove workaround for old compilers in initializations
  jump_label: use ATOMIC_INIT() for initialization of .enabled
  futex: Convert to compiler context analysis
  locking/rwsem: Fix logic error in rwsem_del_waiter()
  locking/rwsem: Add context analysis
  locking/rtmutex: Add context analysis
  locking/mutex: Add context analysis
  compiler-context-analysys: Add __cond_releases()
  locking/mutex: Remove the list_head from struct mutex
  locking/semaphore: Remove the list_head from struct semaphore
  locking/rwsem: Remove the list_head from struct rw_semaphore
  rust: atomic: Update a safety comment in impl of `fetch_add()`
  rust: sync: atomic: Update documentation for `fetch_add()`
  rust: sync: atomic: Add fetch_sub()
  ...

1 files changed, 19 insertions, 5 deletions

diff --git a/arch/arm64/include/asm/rwonce.h b/arch/arm64/include/asm/rwonce.h
index fc0fb42b0b64..0f3a01d30f66 100644
--- a/arch/arm64/include/asm/rwonce.h
+++ b/arch/arm64/include/asm/rwonce.h
@@ -20,6 +20,17 @@
 	ARM64_HAS_LDAPR)
 
 /*
+ * Replace this with typeof_unqual() when minimum compiler versions are
+ * increased to GCC 14 and Clang 19. For the time being, we need this
+ * workaround, which relies on function return values dropping qualifiers.
+ */
+#define __rwonce_typeof_unqual(x) typeof(({				\
+	__diag_push()							\
+	__diag_ignore_all("-Wignored-qualifiers", "")			\
+	((typeof(x)(*)(void))0)();					\
+	__diag_pop() }))
+
+/*
  * When building with LTO, there is an increased risk of the compiler
  * converting an address dependency headed by a READ_ONCE() invocation
  * into a control dependency and consequently allowing for harmful
@@ -31,9 +42,12 @@
  */
 #define __READ_ONCE(x)							\
 ({									\
-	typeof(&(x)) __x = &(x);					\
-	int atomic = 1;							\
-	union { __unqual_scalar_typeof(*__x) __val; char __c[1]; } __u;	\
+	auto __x = &(x);						\
+	auto __ret = (__rwonce_typeof_unqual(*__x) *)__x;		\
+	/* Hides alias reassignment from Clang's -Wthread-safety. */	\
+	auto __retp = &__ret;						\
+	union { typeof(*__ret) __val; char __c[1]; } __u;		\
+	*__retp = &__u.__val;						\
 	switch (sizeof(x)) {						\
 	case 1:								\
 		asm volatile(__LOAD_RCPC(b, %w0, %1)			\
@@ -56,9 +70,9 @@
 			: "Q" (*__x) : "memory");			\
 		break;							\
 	default:							\
-		atomic = 0;						\
+		__u.__val = *(volatile typeof(*__x) *)__x;		\
 	}								\
-	atomic ? (typeof(*__x))__u.__val : (*(volatile typeof(*__x) *)__x);\
+	*__ret;								\
 })
 
 #endif	/* !BUILD_VDSO */