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
  ...

2 files changed, 41 insertions, 10 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index fcad505e7c8b..188f3fd6bdd3 100644
--- a/lib/Kconfig.debug
+++ b/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
diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c
index 6f6a5fc85b42..6e0c019f71b6 100644
--- a/lib/locking-selftest.c
+++ b/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;