Locking changes for v6.13 are:

- lockdep:
     - Enable PROVE_RAW_LOCK_NESTING with PROVE_LOCKING (Sebastian Andrzej Siewior)
     - Add lockdep_cleanup_dead_cpu() (David Woodhouse)
 
  - futexes:
     - Use atomic64_inc_return() in get_inode_sequence_number() (Uros Bizjak)
     - Use atomic64_try_cmpxchg_relaxed() in get_inode_sequence_number() (Uros Bizjak)
 
  - RT locking:
     - Add sparse annotation PREEMPT_RT's locking (Sebastian Andrzej Siewior)
 
  - spinlocks:
     - Use atomic_try_cmpxchg_release() in osq_unlock() (Uros Bizjak)
 
  - atomics:
     - x86: Use ALT_OUTPUT_SP() for __alternative_atomic64() (Uros Bizjak)
     - x86: Use ALT_OUTPUT_SP() for __arch_{,try_}cmpxchg64_emu() (Uros Bizjak)
 
  - KCSAN, seqlocks:
     - Support seqcount_latch_t (Marco Elver)
 
  - <linux/cleanup.h>:
     - Add if_not_cond_guard() conditional guard helper (David Lechner)
     - Adjust scoped_guard() macros to avoid potential warning (Przemek Kitszel)
     - Remove address space of returned pointer (Uros Bizjak)
 
  - WW mutexes:
     - locking/ww_mutex: Adjust to lockdep nest_lock requirements (Thomas Hellström)
 
  - Rust integration:
     - Fix raw_spin_lock initialization on PREEMPT_RT (Eder Zulian)
 
  - miscellaneous cleanups & fixes:
     - lockdep: Fix wait-type check related warnings (Ahmed Ehab)
     - lockdep: Use info level for initial info messages (Jiri Slaby)
     - spinlocks: Make __raw_* lock ops static (Geert Uytterhoeven)
     - pvqspinlock: Convert fields of 'enum vcpu_state' to uppercase (Qiuxu Zhuo)
     - iio: magnetometer: Fix if () scoped_guard() formatting (Stephen Rothwell)
     - rtmutex: Fix misleading comment (Peter Zijlstra)
     - percpu-rw-semaphores: Fix grammar in percpu-rw-semaphore.rst (Xiu Jianfeng)
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "Lockdep:
   - Enable PROVE_RAW_LOCK_NESTING with PROVE_LOCKING (Sebastian Andrzej
     Siewior)
   - Add lockdep_cleanup_dead_cpu() (David Woodhouse)

  futexes:
   - Use atomic64_inc_return() in get_inode_sequence_number() (Uros
     Bizjak)
   - Use atomic64_try_cmpxchg_relaxed() in get_inode_sequence_number()
     (Uros Bizjak)

  RT locking:
   - Add sparse annotation PREEMPT_RT's locking (Sebastian Andrzej
     Siewior)

  spinlocks:
   - Use atomic_try_cmpxchg_release() in osq_unlock() (Uros Bizjak)

  atomics:
   - x86: Use ALT_OUTPUT_SP() for __alternative_atomic64() (Uros Bizjak)
   - x86: Use ALT_OUTPUT_SP() for __arch_{,try_}cmpxchg64_emu() (Uros
     Bizjak)

  KCSAN, seqlocks:
   - Support seqcount_latch_t (Marco Elver)

  <linux/cleanup.h>:
   - Add if_not_guard() conditional guard helper (David Lechner)
   - Adjust scoped_guard() macros to avoid potential warning (Przemek
     Kitszel)
   - Remove address space of returned pointer (Uros Bizjak)

  WW mutexes:
   - locking/ww_mutex: Adjust to lockdep nest_lock requirements (Thomas
     Hellström)

  Rust integration:
   - Fix raw_spin_lock initialization on PREEMPT_RT (Eder Zulian)

  Misc cleanups & fixes:
   - lockdep: Fix wait-type check related warnings (Ahmed Ehab)
   - lockdep: Use info level for initial info messages (Jiri Slaby)
   - spinlocks: Make __raw_* lock ops static (Geert Uytterhoeven)
   - pvqspinlock: Convert fields of 'enum vcpu_state' to uppercase
     (Qiuxu Zhuo)
   - iio: magnetometer: Fix if () scoped_guard() formatting (Stephen
     Rothwell)
   - rtmutex: Fix misleading comment (Peter Zijlstra)
   - percpu-rw-semaphores: Fix grammar in percpu-rw-semaphore.rst (Xiu
     Jianfeng)"

* tag 'locking-core-2024-11-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (29 commits)
  locking/Documentation: Fix grammar in percpu-rw-semaphore.rst
  iio: magnetometer: fix if () scoped_guard() formatting
  rust: helpers: Avoid raw_spin_lock initialization for PREEMPT_RT
  kcsan, seqlock: Fix incorrect assumption in read_seqbegin()
  seqlock, treewide: Switch to non-raw seqcount_latch interface
  kcsan, seqlock: Support seqcount_latch_t
  time/sched_clock: Broaden sched_clock()'s instrumentation coverage
  time/sched_clock: Swap update_clock_read_data() latch writes
  locking/atomic/x86: Use ALT_OUTPUT_SP() for __arch_{,try_}cmpxchg64_emu()
  locking/atomic/x86: Use ALT_OUTPUT_SP() for __alternative_atomic64()
  cleanup: Add conditional guard helper
  cleanup: Adjust scoped_guard() macros to avoid potential warning
  locking/osq_lock: Use atomic_try_cmpxchg_release() in osq_unlock()
  cleanup: Remove address space of returned pointer
  locking/rtmutex: Fix misleading comment
  locking/rt: Annotate unlock followed by lock for sparse.
  locking/rt: Add sparse annotation for RCU.
  locking/rt: Remove one __cond_lock() in RT's spin_trylock_irqsave()
  locking/rt: Add sparse annotation PREEMPT_RT's sleeping locks.
  locking/pvqspinlock: Convert fields of 'enum vcpu_state' to uppercase
  ...

Documentation/locking/percpu-rw-semaphore.rst

@@ -16,8 +16,8 @@ writing is very expensive, it calls synchronize_rcu() that can take
 hundreds of milliseconds.
 
 The lock is declared with "struct percpu_rw_semaphore" type.
-The lock is initialized percpu_init_rwsem, it returns 0 on success and
+The lock is initialized with percpu_init_rwsem, it returns 0 on success
--ENOMEM on allocation failure.
+and -ENOMEM on allocation failure.
 The lock must be freed with percpu_free_rwsem to avoid memory leak.
 
 The lock is locked for read with percpu_down_read, percpu_up_read and

Documentation/locking/seqlock.rst

@@ -153,7 +153,7 @@ Use seqcount_latch_t when the write side sections cannot be protected
 from interruption by readers. This is typically the case when the read
 side can be invoked from NMI handlers.
 
-Check `raw_write_seqcount_latch()` for more information.
+Check `write_seqcount_latch()` for more information.
 
 
 .. _seqlock_t:

arch/x86/include/asm/atomic64_32.h

@@ -51,7 +51,8 @@ static __always_inline s64 arch_atomic64_read_nonatomic(const atomic64_t *v)
 #ifdef CONFIG_X86_CMPXCHG64
 #define __alternative_atomic64(f, g, out, in...) \
 	asm volatile("call %c[func]" \
-		     : out : [func] "i" (atomic64_##g##_cx8), ## in)
+		     : ALT_OUTPUT_SP(out) \
+		     : [func] "i" (atomic64_##g##_cx8), ## in)
 
 #define ATOMIC64_DECL(sym) ATOMIC64_DECL_ONE(sym##_cx8)
 #else

arch/x86/include/asm/cmpxchg_32.h

@@ -94,7 +94,7 @@ static __always_inline bool __try_cmpxchg64_local(volatile u64 *ptr, u64 *oldp,
 	asm volatile(ALTERNATIVE(_lock_loc				\
 				 "call cmpxchg8b_emu",			\
 				 _lock "cmpxchg8b %a[ptr]", X86_FEATURE_CX8) \
-		     : "+a" (o.low), "+d" (o.high)			\
+		     : ALT_OUTPUT_SP("+a" (o.low), "+d" (o.high))	\
 		     : "b" (n.low), "c" (n.high), [ptr] "S" (_ptr)	\
 		     : "memory");					\
 									\
@@ -123,8 +123,8 @@ static __always_inline u64 arch_cmpxchg64_local(volatile u64 *ptr, u64 old, u64
 				 "call cmpxchg8b_emu",			\
 				 _lock "cmpxchg8b %a[ptr]", X86_FEATURE_CX8) \
 		     CC_SET(e)						\
-		     : CC_OUT(e) (ret),					\
+		     : ALT_OUTPUT_SP(CC_OUT(e) (ret),			\
-		       "+a" (o.low), "+d" (o.high)			\
+				     "+a" (o.low), "+d" (o.high))	\
 		     : "b" (n.low), "c" (n.high), [ptr] "S" (_ptr)	\
 		     : "memory");					\
 									\

arch/x86/kernel/tsc.c

@@ -174,10 +174,11 @@ static void __set_cyc2ns_scale(unsigned long khz, int cpu, unsigned long long ts
 
 	c2n = per_cpu_ptr(&cyc2ns, cpu);
 
-	raw_write_seqcount_latch(&c2n->seq);
+	write_seqcount_latch_begin(&c2n->seq);
 	c2n->data[0] = data;
-	raw_write_seqcount_latch(&c2n->seq);
+	write_seqcount_latch(&c2n->seq);
 	c2n->data[1] = data;
+	write_seqcount_latch_end(&c2n->seq);
 }
 
 static void set_cyc2ns_scale(unsigned long khz, int cpu, unsigned long long tsc_now)

drivers/iio/magnetometer/af8133j.c

@@ -312,10 +312,11 @@ static int af8133j_set_scale(struct af8133j_data *data,
 	 * When suspended, just store the new range to data->range to be
 	 * applied later during power up.
 	 */
-	if (!pm_runtime_status_suspended(dev))
+	if (!pm_runtime_status_suspended(dev)) {
 		scoped_guard(mutex, &data->mutex)
 			ret = regmap_write(data->regmap,
 					   AF8133J_REG_RANGE, range);
+	}
 
 	pm_runtime_enable(dev);
 

include/linux/cleanup.h

@@ -273,6 +273,12 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
  *	an anonymous instance of the (guard) class, not recommended for
  *	conditional locks.
  *
+ * if_not_guard(name, args...) { <error handling> }:
+ *	convenience macro for conditional guards that calls the statement that
+ *	follows only if the lock was not acquired (typically an error return).
+ *
+ *	Only for conditional locks.
+ *
  * scoped_guard (name, args...) { }:
  *	similar to CLASS(name, scope)(args), except the variable (with the
  *	explicit name 'scope') is declard in a for-loop such that its scope is
@@ -285,14 +291,20 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
  *      similar to scoped_guard(), except it does fail when the lock
  *      acquire fails.
  *
+ *      Only for conditional locks.
  */
 
+#define __DEFINE_CLASS_IS_CONDITIONAL(_name, _is_cond)	\
+static __maybe_unused const bool class_##_name##_is_conditional = _is_cond
+
 #define DEFINE_GUARD(_name, _type, _lock, _unlock) \
+	__DEFINE_CLASS_IS_CONDITIONAL(_name, false); \
 	DEFINE_CLASS(_name, _type, if (_T) { _unlock; }, ({ _lock; _T; }), _type _T); \
 	static inline void * class_##_name##_lock_ptr(class_##_name##_t *_T) \
-	{ return *_T; }
+	{ return (void *)(__force unsigned long)*_T; }
 
 #define DEFINE_GUARD_COND(_name, _ext, _condlock) \
+	__DEFINE_CLASS_IS_CONDITIONAL(_name##_ext, true); \
 	EXTEND_CLASS(_name, _ext, \
 		     ({ void *_t = _T; if (_T && !(_condlock)) _t = NULL; _t; }), \
 		     class_##_name##_t _T) \
@@ -303,16 +315,48 @@ static inline class_##_name##_t class_##_name##ext##_constructor(_init_args) \
 	CLASS(_name, __UNIQUE_ID(guard))
 
 #define __guard_ptr(_name) class_##_name##_lock_ptr
+#define __is_cond_ptr(_name) class_##_name##_is_conditional
+
+/*
+ * Helper macro for scoped_guard().
+ *
+ * Note that the "!__is_cond_ptr(_name)" part of the condition ensures that
+ * compiler would be sure that for the unconditional locks the body of the
+ * loop (caller-provided code glued to the else clause) could not be skipped.
+ * It is needed because the other part - "__guard_ptr(_name)(&scope)" - is too
+ * hard to deduce (even if could be proven true for unconditional locks).
+ */
+#define __scoped_guard(_name, _label, args...)				\
+	for (CLASS(_name, scope)(args);					\
+	     __guard_ptr(_name)(&scope) || !__is_cond_ptr(_name);	\
+	     ({ goto _label; }))					\
+		if (0) {						\
+_label:									\
+			break;						\
+		} else
 
 #define scoped_guard(_name, args...)	\
-	for (CLASS(_name, scope)(args),					\
+	__scoped_guard(_name, __UNIQUE_ID(label), args)
-	     *done = NULL; __guard_ptr(_name)(&scope) && !done; done = (void *)1)
+
+#define __scoped_cond_guard(_name, _fail, _label, args...)		\
+	for (CLASS(_name, scope)(args); true; ({ goto _label; }))	\
+		if (!__guard_ptr(_name)(&scope)) {			\
+			BUILD_BUG_ON(!__is_cond_ptr(_name));		\
+			_fail;						\
+_label:									\
+			break;						\
+		} else
 
 #define scoped_cond_guard(_name, _fail, args...)	\
-	for (CLASS(_name, scope)(args), \
+	__scoped_cond_guard(_name, _fail, __UNIQUE_ID(label), args)
-	     *done = NULL; !done; done = (void *)1) \
+
-		if (!__guard_ptr(_name)(&scope)) _fail; \
+#define __if_not_guard(_name, _id, args...)		\
-		else
+	BUILD_BUG_ON(!__is_cond_ptr(_name));		\
+	CLASS(_name, _id)(args);			\
+	if (!__guard_ptr(_name)(&_id))
+
+#define if_not_guard(_name, args...) \
+	__if_not_guard(_name, __UNIQUE_ID(guard), args)
 
 /*
  * Additional helper macros for generating lock guards with types, either for
@@ -347,7 +391,7 @@ static inline void class_##_name##_destructor(class_##_name##_t *_T)	\
 									\
 static inline void *class_##_name##_lock_ptr(class_##_name##_t *_T)	\
 {									\
-	return _T->lock;						\
+	return (void *)(__force unsigned long)_T->lock;			\
 }
 
 
@@ -369,14 +413,17 @@ static inline class_##_name##_t class_##_name##_constructor(void)	\
 }
 
 #define DEFINE_LOCK_GUARD_1(_name, _type, _lock, _unlock, ...)		\
+__DEFINE_CLASS_IS_CONDITIONAL(_name, false);				\
 __DEFINE_UNLOCK_GUARD(_name, _type, _unlock, __VA_ARGS__)		\
 __DEFINE_LOCK_GUARD_1(_name, _type, _lock)
 
 #define DEFINE_LOCK_GUARD_0(_name, _lock, _unlock, ...)			\
+__DEFINE_CLASS_IS_CONDITIONAL(_name, false);				\
 __DEFINE_UNLOCK_GUARD(_name, void, _unlock, __VA_ARGS__)		\
 __DEFINE_LOCK_GUARD_0(_name, _lock)
 
 #define DEFINE_LOCK_GUARD_1_COND(_name, _ext, _condlock)		\
+	__DEFINE_CLASS_IS_CONDITIONAL(_name##_ext, true);		\
 	EXTEND_CLASS(_name, _ext,					\
 		     ({ class_##_name##_t _t = { .lock = l }, *_T = &_t;\
 		        if (_T->lock && !(_condlock)) _T->lock = NULL;	\

include/linux/irqflags.h

@@ -18,6 +18,8 @@
 #include <asm/irqflags.h>
 #include <asm/percpu.h>
 
+struct task_struct;
+
 /* Currently lockdep_softirqs_on/off is used only by lockdep */
 #ifdef CONFIG_PROVE_LOCKING
   extern void lockdep_softirqs_on(unsigned long ip);
@@ -25,12 +27,16 @@
   extern void lockdep_hardirqs_on_prepare(void);
   extern void lockdep_hardirqs_on(unsigned long ip);
   extern void lockdep_hardirqs_off(unsigned long ip);
+  extern void lockdep_cleanup_dead_cpu(unsigned int cpu,
+				       struct task_struct *idle);
 #else
   static inline void lockdep_softirqs_on(unsigned long ip) { }
   static inline void lockdep_softirqs_off(unsigned long ip) { }
   static inline void lockdep_hardirqs_on_prepare(void) { }
   static inline void lockdep_hardirqs_on(unsigned long ip) { }
   static inline void lockdep_hardirqs_off(unsigned long ip) { }
+  static inline void lockdep_cleanup_dead_cpu(unsigned int cpu,
+					      struct task_struct *idle) {}
 #endif
 
 #ifdef CONFIG_TRACE_IRQFLAGS

include/linux/lockdep.h

@@ -173,7 +173,7 @@ static inline void lockdep_init_map(struct lockdep_map *lock, const char *name,
 			      (lock)->dep_map.lock_type)
 
 #define lockdep_set_subclass(lock, sub)					\
-	lockdep_init_map_type(&(lock)->dep_map, #lock, (lock)->dep_map.key, sub,\
+	lockdep_init_map_type(&(lock)->dep_map, (lock)->dep_map.name, (lock)->dep_map.key, sub,\
 			      (lock)->dep_map.wait_type_inner,		\
 			      (lock)->dep_map.wait_type_outer,		\
 			      (lock)->dep_map.lock_type)

include/linux/rbtree_latch.h

@@ -14,7 +14,7 @@
  *
  * If we need to allow unconditional lookups (say as required for NMI context
  * usage) we need a more complex setup; this data structure provides this by
- * employing the latch technique -- see @raw_write_seqcount_latch -- to
+ * employing the latch technique -- see @write_seqcount_latch_begin -- to
  * implement a latched RB-tree which does allow for unconditional lookups by
  * virtue of always having (at least) one stable copy of the tree.
  *
@@ -132,7 +132,7 @@ __lt_find(void *key, struct latch_tree_root *ltr, int idx,
  * @ops: operators defining the node order
  *
  * It inserts @node into @root in an ordered fashion such that we can always
- * observe one complete tree. See the comment for raw_write_seqcount_latch().
+ * observe one complete tree. See the comment for write_seqcount_latch_begin().
  *
  * The inserts use rcu_assign_pointer() to publish the element such that the
  * tree structure is stored before we can observe the new @node.
@@ -145,10 +145,11 @@ latch_tree_insert(struct latch_tree_node *node,
 		  struct latch_tree_root *root,
 		  const struct latch_tree_ops *ops)
 {
-	raw_write_seqcount_latch(&root->seq);
+	write_seqcount_latch_begin(&root->seq);
 	__lt_insert(node, root, 0, ops->less);
-	raw_write_seqcount_latch(&root->seq);
+	write_seqcount_latch(&root->seq);
 	__lt_insert(node, root, 1, ops->less);
+	write_seqcount_latch_end(&root->seq);
 }
 
 /**
@@ -159,7 +160,7 @@ latch_tree_insert(struct latch_tree_node *node,
  *
  * Removes @node from the trees @root in an ordered fashion such that we can
  * always observe one complete tree. See the comment for
- * raw_write_seqcount_latch().
+ * write_seqcount_latch_begin().
  *
  * It is assumed that @node will observe one RCU quiescent state before being
  * reused of freed.
@@ -172,10 +173,11 @@ latch_tree_erase(struct latch_tree_node *node,
 		 struct latch_tree_root *root,
 		 const struct latch_tree_ops *ops)
 {
-	raw_write_seqcount_latch(&root->seq);
+	write_seqcount_latch_begin(&root->seq);
 	__lt_erase(node, root, 0);
-	raw_write_seqcount_latch(&root->seq);
+	write_seqcount_latch(&root->seq);
 	__lt_erase(node, root, 1);
+	write_seqcount_latch_end(&root->seq);
 }
 
 /**
@@ -204,9 +206,9 @@ latch_tree_find(void *key, struct latch_tree_root *root,
 	unsigned int seq;
 
 	do {
-		seq = raw_read_seqcount_latch(&root->seq);
+		seq = read_seqcount_latch(&root->seq);
 		node = __lt_find(key, root, seq & 1, ops->comp);
-	} while (raw_read_seqcount_latch_retry(&root->seq, seq));
+	} while (read_seqcount_latch_retry(&root->seq, seq));
 
 	return node;
 }

include/linux/rwlock_rt.h

@@ -24,13 +24,13 @@ do {							\
 	__rt_rwlock_init(rwl, #rwl, &__key);		\
 } while (0)
 
-extern void rt_read_lock(rwlock_t *rwlock);
+extern void rt_read_lock(rwlock_t *rwlock)	__acquires(rwlock);
 extern int rt_read_trylock(rwlock_t *rwlock);
-extern void rt_read_unlock(rwlock_t *rwlock);
+extern void rt_read_unlock(rwlock_t *rwlock)	__releases(rwlock);
-extern void rt_write_lock(rwlock_t *rwlock);
+extern void rt_write_lock(rwlock_t *rwlock)	__acquires(rwlock);
-extern void rt_write_lock_nested(rwlock_t *rwlock, int subclass);
+extern void rt_write_lock_nested(rwlock_t *rwlock, int subclass)	__acquires(rwlock);
 extern int rt_write_trylock(rwlock_t *rwlock);
-extern void rt_write_unlock(rwlock_t *rwlock);
+extern void rt_write_unlock(rwlock_t *rwlock)	__releases(rwlock);
 
 static __always_inline void read_lock(rwlock_t *rwlock)
 {

include/linux/seqlock.h

@@ -621,6 +621,23 @@ static __always_inline unsigned raw_read_seqcount_latch(const seqcount_latch_t *
 	return READ_ONCE(s->seqcount.sequence);
 }
 
+/**
+ * read_seqcount_latch() - pick even/odd latch data copy
+ * @s: Pointer to seqcount_latch_t
+ *
+ * See write_seqcount_latch() for details and a full reader/writer usage
+ * example.
+ *
+ * Return: sequence counter raw value. Use the lowest bit as an index for
+ * picking which data copy to read. The full counter must then be checked
+ * with read_seqcount_latch_retry().
+ */
+static __always_inline unsigned read_seqcount_latch(const seqcount_latch_t *s)
+{
+	kcsan_atomic_next(KCSAN_SEQLOCK_REGION_MAX);
+	return raw_read_seqcount_latch(s);
+}
+
 /**
  * raw_read_seqcount_latch_retry() - end a seqcount_latch_t read section
  * @s:		Pointer to seqcount_latch_t
@@ -635,9 +652,34 @@ raw_read_seqcount_latch_retry(const seqcount_latch_t *s, unsigned start)
 	return unlikely(READ_ONCE(s->seqcount.sequence) != start);
 }
 
+/**
+ * read_seqcount_latch_retry() - end a seqcount_latch_t read section
+ * @s:		Pointer to seqcount_latch_t
+ * @start:	count, from read_seqcount_latch()
+ *
+ * Return: true if a read section retry is required, else false
+ */
+static __always_inline int
+read_seqcount_latch_retry(const seqcount_latch_t *s, unsigned start)
+{
+	kcsan_atomic_next(0);
+	return raw_read_seqcount_latch_retry(s, start);
+}
+
 /**
  * raw_write_seqcount_latch() - redirect latch readers to even/odd copy
  * @s: Pointer to seqcount_latch_t
+ */
+static __always_inline void raw_write_seqcount_latch(seqcount_latch_t *s)
+{
+	smp_wmb();	/* prior stores before incrementing "sequence" */
+	s->seqcount.sequence++;
+	smp_wmb();      /* increment "sequence" before following stores */
+}
+
+/**
+ * write_seqcount_latch_begin() - redirect latch readers to odd copy
+ * @s: Pointer to seqcount_latch_t
  *
  * The latch technique is a multiversion concurrency control method that allows
  * queries during non-atomic modifications. If you can guarantee queries never
@@ -665,17 +707,11 @@ raw_read_seqcount_latch_retry(const seqcount_latch_t *s, unsigned start)
  *
  *	void latch_modify(struct latch_struct *latch, ...)
  *	{
- *		smp_wmb();	// Ensure that the last data[1] update is visible
+ *		write_seqcount_latch_begin(&latch->seq);
- *		latch->seq.sequence++;
- *		smp_wmb();	// Ensure that the seqcount update is visible
- *
  *		modify(latch->data[0], ...);
- *
+ *		write_seqcount_latch(&latch->seq);
- *		smp_wmb();	// Ensure that the data[0] update is visible
- *		latch->seq.sequence++;
- *		smp_wmb();	// Ensure that the seqcount update is visible
- *
  *		modify(latch->data[1], ...);
+ *		write_seqcount_latch_end(&latch->seq);
  *	}
  *
  * The query will have a form like::
@@ -686,13 +722,13 @@ raw_read_seqcount_latch_retry(const seqcount_latch_t *s, unsigned start)
  *		unsigned seq, idx;
  *
  *		do {
- *			seq = raw_read_seqcount_latch(&latch->seq);
+ *			seq = read_seqcount_latch(&latch->seq);
  *
  *			idx = seq & 0x01;
  *			entry = data_query(latch->data[idx], ...);
  *
  *		// This includes needed smp_rmb()
- *		} while (raw_read_seqcount_latch_retry(&latch->seq, seq));
+ *		} while (read_seqcount_latch_retry(&latch->seq, seq));
  *
  *		return entry;
  *	}
@@ -716,11 +752,31 @@ raw_read_seqcount_latch_retry(const seqcount_latch_t *s, unsigned start)
  *	When data is a dynamic data structure; one should use regular RCU
  *	patterns to manage the lifetimes of the objects within.
  */
-static inline void raw_write_seqcount_latch(seqcount_latch_t *s)
+static __always_inline void write_seqcount_latch_begin(seqcount_latch_t *s)
 {
-	smp_wmb();	/* prior stores before incrementing "sequence" */
+	kcsan_nestable_atomic_begin();
-	s->seqcount.sequence++;
+	raw_write_seqcount_latch(s);
-	smp_wmb();      /* increment "sequence" before following stores */
+}
+
+/**
+ * write_seqcount_latch() - redirect latch readers to even copy
+ * @s: Pointer to seqcount_latch_t
+ */
+static __always_inline void write_seqcount_latch(seqcount_latch_t *s)
+{
+	raw_write_seqcount_latch(s);
+}
+
+/**
+ * write_seqcount_latch_end() - end a seqcount_latch_t write section
+ * @s:		Pointer to seqcount_latch_t
+ *
+ * Marks the end of a seqcount_latch_t writer section, after all copies of the
+ * latch-protected data have been updated.
+ */
+static __always_inline void write_seqcount_latch_end(seqcount_latch_t *s)
+{
+	kcsan_nestable_atomic_end();
 }
 
 #define __SEQLOCK_UNLOCKED(lockname)					\
@@ -754,11 +810,7 @@ static inline void raw_write_seqcount_latch(seqcount_latch_t *s)
  */
 static inline unsigned read_seqbegin(const seqlock_t *sl)
 {
-	unsigned ret = read_seqcount_begin(&sl->seqcount);
+	return read_seqcount_begin(&sl->seqcount);
-
-	kcsan_atomic_next(0);  /* non-raw usage, assume closing read_seqretry() */
-	kcsan_flat_atomic_begin();
-	return ret;
 }
 
 /**
@@ -774,12 +826,6 @@ static inline unsigned read_seqbegin(const seqlock_t *sl)
  */
 static inline unsigned read_seqretry(const seqlock_t *sl, unsigned start)
 {
-	/*
-	 * Assume not nested: read_seqretry() may be called multiple times when
-	 * completing read critical section.
-	 */
-	kcsan_flat_atomic_end();
-
 	return read_seqcount_retry(&sl->seqcount, start);
 }
 

include/linux/spinlock_rt.h

@@ -16,26 +16,25 @@ static inline void __rt_spin_lock_init(spinlock_t *lock, const char *name,
 }
 #endif
 
-#define spin_lock_init(slock)					\
+#define __spin_lock_init(slock, name, key, percpu)		\
 do {								\
-	static struct lock_class_key __key;			\
-								\
 	rt_mutex_base_init(&(slock)->lock);			\
-	__rt_spin_lock_init(slock, #slock, &__key, false);	\
+	__rt_spin_lock_init(slock, name, key, percpu);		\
 } while (0)
 
-#define local_spin_lock_init(slock)				\
+#define _spin_lock_init(slock, percpu)				\
 do {								\
 	static struct lock_class_key __key;			\
-								\
+	__spin_lock_init(slock, #slock, &__key, percpu);	\
-	rt_mutex_base_init(&(slock)->lock);			\
-	__rt_spin_lock_init(slock, #slock, &__key, true);	\
 } while (0)
 
-extern void rt_spin_lock(spinlock_t *lock);
+#define spin_lock_init(slock)		_spin_lock_init(slock, false)
-extern void rt_spin_lock_nested(spinlock_t *lock, int subclass);
+#define local_spin_lock_init(slock)	_spin_lock_init(slock, true)
-extern void rt_spin_lock_nest_lock(spinlock_t *lock, struct lockdep_map *nest_lock);
+
-extern void rt_spin_unlock(spinlock_t *lock);
+extern void rt_spin_lock(spinlock_t *lock) __acquires(lock);
+extern void rt_spin_lock_nested(spinlock_t *lock, int subclass)	__acquires(lock);
+extern void rt_spin_lock_nest_lock(spinlock_t *lock, struct lockdep_map *nest_lock) __acquires(lock);
+extern void rt_spin_unlock(spinlock_t *lock)	__releases(lock);
 extern void rt_spin_lock_unlock(spinlock_t *lock);
 extern int rt_spin_trylock_bh(spinlock_t *lock);
 extern int rt_spin_trylock(spinlock_t *lock);
@@ -132,7 +131,7 @@ static __always_inline void spin_unlock_irqrestore(spinlock_t *lock,
 #define spin_trylock_irq(lock)				\
 	__cond_lock(lock, rt_spin_trylock(lock))
 
-#define __spin_trylock_irqsave(lock, flags)		\
+#define spin_trylock_irqsave(lock, flags)		\
 ({							\
 	int __locked;					\
 							\
@@ -142,9 +141,6 @@ static __always_inline void spin_unlock_irqrestore(spinlock_t *lock,
 	__locked;					\
 })
 
-#define spin_trylock_irqsave(lock, flags)		\
-	__cond_lock(lock, __spin_trylock_irqsave(lock, flags))
-
 #define spin_is_contended(lock)		(((void)(lock), 0))
 
 static inline int spin_is_locked(spinlock_t *lock)

include/linux/ww_mutex.h

@@ -65,6 +65,16 @@ struct ww_acquire_ctx {
 #endif
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 	struct lockdep_map dep_map;
+	/**
+	 * @first_lock_dep_map: fake lockdep_map for first locked ww_mutex.
+	 *
+	 * lockdep requires the lockdep_map for the first locked ww_mutex
+	 * in a ww transaction to remain in memory until all ww_mutexes of
+	 * the transaction have been unlocked. Ensure this by keeping a
+	 * fake locked ww_mutex lockdep map between ww_acquire_init() and
+	 * ww_acquire_fini().
+	 */
+	struct lockdep_map first_lock_dep_map;
 #endif
 #ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
 	unsigned int deadlock_inject_interval;
@@ -146,7 +156,10 @@ static inline void ww_acquire_init(struct ww_acquire_ctx *ctx,
 	debug_check_no_locks_freed((void *)ctx, sizeof(*ctx));
 	lockdep_init_map(&ctx->dep_map, ww_class->acquire_name,
 			 &ww_class->acquire_key, 0);
+	lockdep_init_map(&ctx->first_lock_dep_map, ww_class->mutex_name,
+			 &ww_class->mutex_key, 0);
 	mutex_acquire(&ctx->dep_map, 0, 0, _RET_IP_);
+	mutex_acquire_nest(&ctx->first_lock_dep_map, 0, 0, &ctx->dep_map, _RET_IP_);
 #endif
 #ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
 	ctx->deadlock_inject_interval = 1;
@@ -185,6 +198,7 @@ static inline void ww_acquire_done(struct ww_acquire_ctx *ctx)
 static inline void ww_acquire_fini(struct ww_acquire_ctx *ctx)
 {
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
+	mutex_release(&ctx->first_lock_dep_map, _THIS_IP_);
 	mutex_release(&ctx->dep_map, _THIS_IP_);
 #endif
 #ifdef DEBUG_WW_MUTEXES

kernel/cpu.c

@@ -1338,6 +1338,7 @@ static int takedown_cpu(unsigned int cpu)
 
 	cpuhp_bp_sync_dead(cpu);
 
+	lockdep_cleanup_dead_cpu(cpu, idle_thread_get(cpu));
 	tick_cleanup_dead_cpu(cpu);
 
 	/*

kernel/futex/core.c

@@ -181,12 +181,12 @@ static u64 get_inode_sequence_number(struct inode *inode)
 		return old;
 
 	for (;;) {
-		u64 new = atomic64_add_return(1, &i_seq);
+		u64 new = atomic64_inc_return(&i_seq);
 		if (WARN_ON_ONCE(!new))
 			continue;
 
-		old = atomic64_cmpxchg_relaxed(&inode->i_sequence, 0, new);
+		old = 0;
-		if (old)
+		if (!atomic64_try_cmpxchg_relaxed(&inode->i_sequence, &old, new))
 			return old;
 		return new;
 	}

kernel/locking/lockdep.c

@@ -4586,6 +4586,30 @@ void lockdep_softirqs_off(unsigned long ip)
 		debug_atomic_inc(redundant_softirqs_off);
 }
 
+/**
+ * lockdep_cleanup_dead_cpu - Ensure CPU lockdep state is cleanly stopped
+ *
+ * @cpu: index of offlined CPU
+ * @idle: task pointer for offlined CPU's idle thread
+ *
+ * Invoked after the CPU is dead. Ensures that the tracing infrastructure
+ * is left in a suitable state for the CPU to be subsequently brought
+ * online again.
+ */
+void lockdep_cleanup_dead_cpu(unsigned int cpu, struct task_struct *idle)
+{
+	if (unlikely(!debug_locks))
+		return;
+
+	if (unlikely(per_cpu(hardirqs_enabled, cpu))) {
+		pr_warn("CPU %u left hardirqs enabled!", cpu);
+		if (idle)
+			print_irqtrace_events(idle);
+		/* Clean it up for when the CPU comes online again. */
+		per_cpu(hardirqs_enabled, cpu) = 0;
+	}
+}
+
 static int
 mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
 {
@@ -6576,17 +6600,17 @@ EXPORT_SYMBOL_GPL(lockdep_unregister_key);
 
 void __init lockdep_init(void)
 {
-	printk("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
+	pr_info("Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar\n");
 
-	printk("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
+	pr_info("... MAX_LOCKDEP_SUBCLASSES:  %lu\n", MAX_LOCKDEP_SUBCLASSES);
-	printk("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
+	pr_info("... MAX_LOCK_DEPTH:          %lu\n", MAX_LOCK_DEPTH);
-	printk("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
+	pr_info("... MAX_LOCKDEP_KEYS:        %lu\n", MAX_LOCKDEP_KEYS);
-	printk("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
+	pr_info("... CLASSHASH_SIZE:          %lu\n", CLASSHASH_SIZE);
-	printk("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
+	pr_info("... MAX_LOCKDEP_ENTRIES:     %lu\n", MAX_LOCKDEP_ENTRIES);
-	printk("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
+	pr_info("... MAX_LOCKDEP_CHAINS:      %lu\n", MAX_LOCKDEP_CHAINS);
-	printk("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
+	pr_info("... CHAINHASH_SIZE:          %lu\n", CHAINHASH_SIZE);
 
-	printk(" memory used by lock dependency info: %zu kB\n",
+	pr_info(" memory used by lock dependency info: %zu kB\n",
 	       (sizeof(lock_classes) +
 		sizeof(lock_classes_in_use) +
 		sizeof(classhash_table) +
@@ -6604,12 +6628,12 @@ void __init lockdep_init(void)
 		);
 
 #if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
-	printk(" memory used for stack traces: %zu kB\n",
+	pr_info(" memory used for stack traces: %zu kB\n",
 	       (sizeof(stack_trace) + sizeof(stack_trace_hash)) / 1024
 	       );
 #endif
 
-	printk(" per task-struct memory footprint: %zu bytes\n",
+	pr_info(" per task-struct memory footprint: %zu bytes\n",
 	       sizeof(((struct task_struct *)NULL)->held_locks));
 }
 

kernel/locking/osq_lock.c

@@ -215,8 +215,7 @@ void osq_unlock(struct optimistic_spin_queue *lock)
 	/*
 	 * Fast path for the uncontended case.
 	 */
-	if (likely(atomic_cmpxchg_release(&lock->tail, curr,
+	if (atomic_try_cmpxchg_release(&lock->tail, &curr, OSQ_UNLOCKED_VAL))
-					  OSQ_UNLOCKED_VAL) == curr))
 		return;
 
 	/*

kernel/locking/qspinlock_paravirt.h

@@ -38,13 +38,13 @@
 #define PV_PREV_CHECK_MASK	0xff
 
 /*
- * Queue node uses: vcpu_running & vcpu_halted.
+ * Queue node uses: VCPU_RUNNING & VCPU_HALTED.
- * Queue head uses: vcpu_running & vcpu_hashed.
+ * Queue head uses: VCPU_RUNNING & VCPU_HASHED.
  */
 enum vcpu_state {
-	vcpu_running = 0,
+	VCPU_RUNNING = 0,
-	vcpu_halted,		/* Used only in pv_wait_node */
+	VCPU_HALTED,		/* Used only in pv_wait_node */
-	vcpu_hashed,		/* = pv_hash'ed + vcpu_halted */
+	VCPU_HASHED,		/* = pv_hash'ed + VCPU_HALTED */
 };
 
 struct pv_node {
@@ -266,7 +266,7 @@ pv_wait_early(struct pv_node *prev, int loop)
 	if ((loop & PV_PREV_CHECK_MASK) != 0)
 		return false;
 
-	return READ_ONCE(prev->state) != vcpu_running;
+	return READ_ONCE(prev->state) != VCPU_RUNNING;
 }
 
 /*
@@ -279,7 +279,7 @@ static void pv_init_node(struct mcs_spinlock *node)
 	BUILD_BUG_ON(sizeof(struct pv_node) > sizeof(struct qnode));
 
 	pn->cpu = smp_processor_id();
-	pn->state = vcpu_running;
+	pn->state = VCPU_RUNNING;
 }
 
 /*
@@ -308,26 +308,26 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev)
 		/*
 		 * Order pn->state vs pn->locked thusly:
 		 *
-		 * [S] pn->state = vcpu_halted	  [S] next->locked = 1
+		 * [S] pn->state = VCPU_HALTED	  [S] next->locked = 1
 		 *     MB			      MB
-		 * [L] pn->locked		[RmW] pn->state = vcpu_hashed
+		 * [L] pn->locked		[RmW] pn->state = VCPU_HASHED
 		 *
 		 * Matches the cmpxchg() from pv_kick_node().
 		 */
-		smp_store_mb(pn->state, vcpu_halted);
+		smp_store_mb(pn->state, VCPU_HALTED);
 
 		if (!READ_ONCE(node->locked)) {
 			lockevent_inc(pv_wait_node);
 			lockevent_cond_inc(pv_wait_early, wait_early);
-			pv_wait(&pn->state, vcpu_halted);
+			pv_wait(&pn->state, VCPU_HALTED);
 		}
 
 		/*
-		 * If pv_kick_node() changed us to vcpu_hashed, retain that
+		 * If pv_kick_node() changed us to VCPU_HASHED, retain that
 		 * value so that pv_wait_head_or_lock() knows to not also try
 		 * to hash this lock.
 		 */
-		cmpxchg(&pn->state, vcpu_halted, vcpu_running);
+		cmpxchg(&pn->state, VCPU_HALTED, VCPU_RUNNING);
 
 		/*
 		 * If the locked flag is still not set after wakeup, it is a
@@ -357,7 +357,7 @@ static void pv_wait_node(struct mcs_spinlock *node, struct mcs_spinlock *prev)
 static void pv_kick_node(struct qspinlock *lock, struct mcs_spinlock *node)
 {
 	struct pv_node *pn = (struct pv_node *)node;
-	u8 old = vcpu_halted;
+	u8 old = VCPU_HALTED;
 	/*
 	 * If the vCPU is indeed halted, advance its state to match that of
 	 * pv_wait_node(). If OTOH this fails, the vCPU was running and will
@@ -374,7 +374,7 @@ static void pv_kick_node(struct qspinlock *lock, struct mcs_spinlock *node)
 	 * subsequent writes.
 	 */
 	smp_mb__before_atomic();
-	if (!try_cmpxchg_relaxed(&pn->state, &old, vcpu_hashed))
+	if (!try_cmpxchg_relaxed(&pn->state, &old, VCPU_HASHED))
 		return;
 
 	/*
@@ -407,7 +407,7 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct mcs_spinlock *node)
 	 * If pv_kick_node() already advanced our state, we don't need to
 	 * insert ourselves into the hash table anymore.
 	 */
-	if (READ_ONCE(pn->state) == vcpu_hashed)
+	if (READ_ONCE(pn->state) == VCPU_HASHED)
 		lp = (struct qspinlock **)1;
 
 	/*
@@ -420,7 +420,7 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct mcs_spinlock *node)
 		 * Set correct vCPU state to be used by queue node wait-early
 		 * mechanism.
 		 */
-		WRITE_ONCE(pn->state, vcpu_running);
+		WRITE_ONCE(pn->state, VCPU_RUNNING);
 
 		/*
 		 * Set the pending bit in the active lock spinning loop to
@@ -460,7 +460,7 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct mcs_spinlock *node)
 				goto gotlock;
 			}
 		}
-		WRITE_ONCE(pn->state, vcpu_hashed);
+		WRITE_ONCE(pn->state, VCPU_HASHED);
 		lockevent_inc(pv_wait_head);
 		lockevent_cond_inc(pv_wait_again, waitcnt);
 		pv_wait(&lock->locked, _Q_SLOW_VAL);

kernel/locking/rtmutex.c

@@ -1601,6 +1601,7 @@ static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock,
 					   unsigned int state,
 					   struct hrtimer_sleeper *timeout,
 					   struct rt_mutex_waiter *waiter)
+	__releases(&lock->wait_lock) __acquires(&lock->wait_lock)
 {
 	struct rt_mutex *rtm = container_of(lock, struct rt_mutex, rtmutex);
 	struct task_struct *owner;
@@ -1805,6 +1806,7 @@ static __always_inline int __rt_mutex_lock(struct rt_mutex_base *lock,
  * @lock:	The underlying RT mutex
  */
 static void __sched rtlock_slowlock_locked(struct rt_mutex_base *lock)
+	__releases(&lock->wait_lock) __acquires(&lock->wait_lock)
 {
 	struct rt_mutex_waiter waiter;
 	struct task_struct *owner;

kernel/locking/rtmutex_api.c

@@ -175,10 +175,10 @@ bool __sched __rt_mutex_futex_unlock(struct rt_mutex_base *lock,
 	}
 
 	/*
-	 * We've already deboosted, mark_wakeup_next_waiter() will
+	 * mark_wakeup_next_waiter() deboosts and retains preemption
-	 * retain preempt_disabled when we drop the wait_lock, to
+	 * disabled when dropping the wait_lock, to avoid inversion prior
-	 * avoid inversion prior to the wakeup.  preempt_disable()
+	 * to the wakeup.  preempt_disable() therein pairs with the
-	 * therein pairs with rt_mutex_postunlock().
+	 * preempt_enable() in rt_mutex_postunlock().
 	 */
 	mark_wakeup_next_waiter(wqh, lock);
 

kernel/locking/spinlock.c

@@ -65,7 +65,7 @@ EXPORT_PER_CPU_SYMBOL(__mmiowb_state);
  * towards that other CPU that it should break the lock ASAP.
  */
 #define BUILD_LOCK_OPS(op, locktype)					\
-void __lockfunc __raw_##op##_lock(locktype##_t *lock)			\
+static void __lockfunc __raw_##op##_lock(locktype##_t *lock)		\
 {									\
 	for (;;) {							\
 		preempt_disable();					\
@@ -77,7 +77,7 @@ void __lockfunc __raw_##op##_lock(locktype##_t *lock)			\
 	}								\
 }									\
 									\
-unsigned long __lockfunc __raw_##op##_lock_irqsave(locktype##_t *lock)	\
+static unsigned long __lockfunc __raw_##op##_lock_irqsave(locktype##_t *lock) \
 {									\
 	unsigned long flags;						\
 									\
@@ -95,12 +95,12 @@ unsigned long __lockfunc __raw_##op##_lock_irqsave(locktype##_t *lock)	\
 	return flags;							\
 }									\
 									\
-void __lockfunc __raw_##op##_lock_irq(locktype##_t *lock)		\
+static void __lockfunc __raw_##op##_lock_irq(locktype##_t *lock)	\
 {									\
 	_raw_##op##_lock_irqsave(lock);					\
 }									\
 									\
-void __lockfunc __raw_##op##_lock_bh(locktype##_t *lock)		\
+static void __lockfunc __raw_##op##_lock_bh(locktype##_t *lock)		\
 {									\
 	unsigned long flags;						\
 									\

kernel/locking/spinlock_rt.c

@@ -51,7 +51,7 @@ static __always_inline void __rt_spin_lock(spinlock_t *lock)
 	migrate_disable();
 }
 
-void __sched rt_spin_lock(spinlock_t *lock)
+void __sched rt_spin_lock(spinlock_t *lock) __acquires(RCU)
 {
 	spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
 	__rt_spin_lock(lock);
@@ -75,7 +75,7 @@ void __sched rt_spin_lock_nest_lock(spinlock_t *lock,
 EXPORT_SYMBOL(rt_spin_lock_nest_lock);
 #endif
 
-void __sched rt_spin_unlock(spinlock_t *lock)
+void __sched rt_spin_unlock(spinlock_t *lock) __releases(RCU)
 {
 	spin_release(&lock->dep_map, _RET_IP_);
 	migrate_enable();
@@ -225,7 +225,7 @@ int __sched rt_write_trylock(rwlock_t *rwlock)
 }
 EXPORT_SYMBOL(rt_write_trylock);
 
-void __sched rt_read_lock(rwlock_t *rwlock)
+void __sched rt_read_lock(rwlock_t *rwlock) __acquires(RCU)
 {
 	rtlock_might_resched();
 	rwlock_acquire_read(&rwlock->dep_map, 0, 0, _RET_IP_);
@@ -235,7 +235,7 @@ void __sched rt_read_lock(rwlock_t *rwlock)
 }
 EXPORT_SYMBOL(rt_read_lock);
 
-void __sched rt_write_lock(rwlock_t *rwlock)
+void __sched rt_write_lock(rwlock_t *rwlock) __acquires(RCU)
 {
 	rtlock_might_resched();
 	rwlock_acquire(&rwlock->dep_map, 0, 0, _RET_IP_);
@@ -246,7 +246,7 @@ void __sched rt_write_lock(rwlock_t *rwlock)
 EXPORT_SYMBOL(rt_write_lock);
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
-void __sched rt_write_lock_nested(rwlock_t *rwlock, int subclass)
+void __sched rt_write_lock_nested(rwlock_t *rwlock, int subclass) __acquires(RCU)
 {
 	rtlock_might_resched();
 	rwlock_acquire(&rwlock->dep_map, subclass, 0, _RET_IP_);
@@ -257,7 +257,7 @@ void __sched rt_write_lock_nested(rwlock_t *rwlock, int subclass)
 EXPORT_SYMBOL(rt_write_lock_nested);
 #endif
 
-void __sched rt_read_unlock(rwlock_t *rwlock)
+void __sched rt_read_unlock(rwlock_t *rwlock) __releases(RCU)
 {
 	rwlock_release(&rwlock->dep_map, _RET_IP_);
 	migrate_enable();
@@ -266,7 +266,7 @@ void __sched rt_read_unlock(rwlock_t *rwlock)
 }
 EXPORT_SYMBOL(rt_read_unlock);
 
-void __sched rt_write_unlock(rwlock_t *rwlock)
+void __sched rt_write_unlock(rwlock_t *rwlock) __releases(RCU)
 {
 	rwlock_release(&rwlock->dep_map, _RET_IP_);
 	rcu_read_unlock();

kernel/locking/test-ww_mutex.c

@@ -62,6 +62,7 @@ static int __test_mutex(unsigned int flags)
 	int ret;
 
 	ww_mutex_init(&mtx.mutex, &ww_class);
+	if (flags & TEST_MTX_CTX)
 		ww_acquire_init(&ctx, &ww_class);
 
 	INIT_WORK_ONSTACK(&mtx.work, test_mutex_work);
@@ -90,6 +91,7 @@ static int __test_mutex(unsigned int flags)
 		ret = wait_for_completion_timeout(&mtx.done, TIMEOUT);
 	}
 	ww_mutex_unlock(&mtx.mutex);
+	if (flags & TEST_MTX_CTX)
 		ww_acquire_fini(&ctx);
 
 	if (ret) {
@@ -679,7 +681,7 @@ static int __init test_ww_mutex_init(void)
 	if (ret)
 		return ret;
 
-	ret = stress(2047, hweight32(STRESS_ALL)*ncpus, STRESS_ALL);
+	ret = stress(2046, hweight32(STRESS_ALL)*ncpus, STRESS_ALL);
 	if (ret)
 		return ret;
 

kernel/printk/printk.c

@@ -560,10 +560,11 @@ bool printk_percpu_data_ready(void)
 /* Must be called under syslog_lock. */
 static void latched_seq_write(struct latched_seq *ls, u64 val)
 {
-	raw_write_seqcount_latch(&ls->latch);
+	write_seqcount_latch_begin(&ls->latch);
 	ls->val[0] = val;
-	raw_write_seqcount_latch(&ls->latch);
+	write_seqcount_latch(&ls->latch);
 	ls->val[1] = val;
+	write_seqcount_latch_end(&ls->latch);
 }
 
 /* Can be called from any context. */
@@ -574,10 +575,10 @@ static u64 latched_seq_read_nolock(struct latched_seq *ls)
 	u64 val;
 
 	do {
-		seq = raw_read_seqcount_latch(&ls->latch);
+		seq = read_seqcount_latch(&ls->latch);
 		idx = seq & 0x1;
 		val = ls->val[idx];
-	} while (raw_read_seqcount_latch_retry(&ls->latch, seq));
+	} while (read_seqcount_latch_retry(&ls->latch, seq));
 
 	return val;
 }

kernel/time/sched_clock.c

@@ -71,16 +71,16 @@ static __always_inline u64 cyc_to_ns(u64 cyc, u32 mult, u32 shift)
 
 notrace struct clock_read_data *sched_clock_read_begin(unsigned int *seq)
 {
-	*seq = raw_read_seqcount_latch(&cd.seq);
+	*seq = read_seqcount_latch(&cd.seq);
 	return cd.read_data + (*seq & 1);
 }
 
 notrace int sched_clock_read_retry(unsigned int seq)
 {
-	return raw_read_seqcount_latch_retry(&cd.seq, seq);
+	return read_seqcount_latch_retry(&cd.seq, seq);
 }
 
-unsigned long long noinstr sched_clock_noinstr(void)
+static __always_inline unsigned long long __sched_clock(void)
 {
 	struct clock_read_data *rd;
 	unsigned int seq;
@@ -98,11 +98,23 @@ unsigned long long noinstr sched_clock_noinstr(void)
 	return res;
 }
 
+unsigned long long noinstr sched_clock_noinstr(void)
+{
+	return __sched_clock();
+}
+
 unsigned long long notrace sched_clock(void)
 {
 	unsigned long long ns;
 	preempt_disable_notrace();
-	ns = sched_clock_noinstr();
+	/*
+	 * All of __sched_clock() is a seqcount_latch reader critical section,
+	 * but relies on the raw helpers which are uninstrumented. For KCSAN,
+	 * mark all accesses in __sched_clock() as atomic.
+	 */
+	kcsan_nestable_atomic_begin();
+	ns = __sched_clock();
+	kcsan_nestable_atomic_end();
 	preempt_enable_notrace();
 	return ns;
 }
@@ -119,17 +131,19 @@ unsigned long long notrace sched_clock(void)
  */
 static void update_clock_read_data(struct clock_read_data *rd)
 {
-	/* update the backup (odd) copy with the new data */
-	cd.read_data[1] = *rd;
-
 	/* steer readers towards the odd copy */
-	raw_write_seqcount_latch(&cd.seq);
+	write_seqcount_latch_begin(&cd.seq);
 
 	/* now its safe for us to update the normal (even) copy */
 	cd.read_data[0] = *rd;
 
 	/* switch readers back to the even copy */
-	raw_write_seqcount_latch(&cd.seq);
+	write_seqcount_latch(&cd.seq);
+
+	/* update the backup (odd) copy with the new data */
+	cd.read_data[1] = *rd;
+
+	write_seqcount_latch_end(&cd.seq);
 }
 
 /*
@@ -267,7 +281,7 @@ void __init generic_sched_clock_init(void)
  */
 static u64 notrace suspended_sched_clock_read(void)
 {
-	unsigned int seq = raw_read_seqcount_latch(&cd.seq);
+	unsigned int seq = read_seqcount_latch(&cd.seq);
 
 	return cd.read_data[seq & 1].epoch_cyc;
 }

kernel/time/timekeeping.c

@@ -428,7 +428,7 @@ static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr)
  * We want to use this from any context including NMI and tracing /
  * instrumenting the timekeeping code itself.
  *
- * Employ the latch technique; see @raw_write_seqcount_latch.
+ * Employ the latch technique; see @write_seqcount_latch.
  *
  * So if a NMI hits the update of base[0] then it will use base[1]
  * which is still consistent. In the worst case this can result is a
@@ -441,16 +441,18 @@ static void update_fast_timekeeper(const struct tk_read_base *tkr,
 	struct tk_read_base *base = tkf->base;
 
 	/* Force readers off to base[1] */
-	raw_write_seqcount_latch(&tkf->seq);
+	write_seqcount_latch_begin(&tkf->seq);
 
 	/* Update base[0] */
 	memcpy(base, tkr, sizeof(*base));
 
 	/* Force readers back to base[0] */
-	raw_write_seqcount_latch(&tkf->seq);
+	write_seqcount_latch(&tkf->seq);
 
 	/* Update base[1] */
 	memcpy(base + 1, base, sizeof(*base));
+
+	write_seqcount_latch_end(&tkf->seq);
 }
 
 static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
@@ -460,11 +462,11 @@ static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
 	u64 now;
 
 	do {
-		seq = raw_read_seqcount_latch(&tkf->seq);
+		seq = read_seqcount_latch(&tkf->seq);
 		tkr = tkf->base + (seq & 0x01);
 		now = ktime_to_ns(tkr->base);
 		now += __timekeeping_get_ns(tkr);
-	} while (raw_read_seqcount_latch_retry(&tkf->seq, seq));
+	} while (read_seqcount_latch_retry(&tkf->seq, seq));
 
 	return now;
 }

lib/Kconfig.debug

@@ -1409,22 +1409,14 @@ config PROVE_LOCKING
 	 For more details, see Documentation/locking/lockdep-design.rst.
 
 config PROVE_RAW_LOCK_NESTING
-	bool "Enable raw_spinlock - spinlock nesting checks"
+	bool
 	depends on PROVE_LOCKING
-	default n
+	default y
 	help
 	 Enable the raw_spinlock vs. spinlock nesting checks which ensure
 	 that the lock nesting rules for PREEMPT_RT enabled kernels are
 	 not violated.
 
-	 NOTE: There are known nesting problems. So if you enable this
-	 option expect lockdep splats until these problems have been fully
-	 addressed which is work in progress. This config switch allows to
-	 identify and analyze these problems. It will be removed and the
-	 check permanently enabled once the main issues have been fixed.
-
-	 If unsure, select N.
-
 config LOCK_STAT
 	bool "Lock usage statistics"
 	depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT

lib/locking-selftest.c

@@ -2710,6 +2710,43 @@ static void local_lock_3B(void)
 
 }
 
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+static inline const char *rw_semaphore_lockdep_name(struct rw_semaphore *rwsem)
+{
+	return rwsem->dep_map.name;
+}
+#else
+static inline const char *rw_semaphore_lockdep_name(struct rw_semaphore *rwsem)
+{
+	return NULL;
+}
+#endif
+
+static void test_lockdep_set_subclass_name(void)
+{
+	const char *name_before = rw_semaphore_lockdep_name(&rwsem_X1);
+	const char *name_after;
+
+	lockdep_set_subclass(&rwsem_X1, 1);
+	name_after = rw_semaphore_lockdep_name(&rwsem_X1);
+	DEBUG_LOCKS_WARN_ON(name_before != name_after);
+}
+
+/*
+ * lockdep_set_subclass() should reuse the existing lock class name instead
+ * of creating a new one.
+ */
+static void lockdep_set_subclass_name_test(void)
+{
+	printk("  --------------------------------------------------------------------------\n");
+	printk("  | lockdep_set_subclass() name test|\n");
+	printk("  -----------------------------------\n");
+
+	print_testname("compare name before and after");
+	dotest(test_lockdep_set_subclass_name, SUCCESS, LOCKTYPE_RWSEM);
+	pr_cont("\n");
+}
+
 static void local_lock_tests(void)
 {
 	printk("  --------------------------------------------------------------------------\n");
@@ -2920,6 +2957,8 @@ void locking_selftest(void)
 	dotest(hardirq_deadlock_softirq_not_deadlock, FAILURE, LOCKTYPE_SPECIAL);
 	pr_cont("\n");
 
+	lockdep_set_subclass_name_test();
+
 	if (unexpected_testcase_failures) {
 		printk("-----------------------------------------------------------------\n");
 		debug_locks = 0;

rust/helpers/spinlock.c

@@ -7,10 +7,14 @@ void rust_helper___spin_lock_init(spinlock_t *lock, const char *name,
 				  struct lock_class_key *key)
 {
 #ifdef CONFIG_DEBUG_SPINLOCK
+# if defined(CONFIG_PREEMPT_RT)
+	__spin_lock_init(lock, name, key, false);
+# else /*!CONFIG_PREEMPT_RT */
 	__raw_spin_lock_init(spinlock_check(lock), name, key, LD_WAIT_CONFIG);
-#else
+# endif /* CONFIG_PREEMPT_RT */
+#else /* !CONFIG_DEBUG_SPINLOCK */
 	spin_lock_init(lock);
-#endif
+#endif /* CONFIG_DEBUG_SPINLOCK */
 }
 
 void rust_helper_spin_lock(spinlock_t *lock)