Merge tag 'locking-core-2024-03-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar: - Micro-optimize local_xchg() and the rtmutex code on x86 - Fix percpu-rwsem contention tracepoints - Simplify debugging Kconfig dependencies - Update/clarify the documentation of atomic primitives - Misc cleanups * tag 'locking-core-2024-03-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/rtmutex: Use try_cmpxchg_relaxed() in mark_rt_mutex_waiters() locking/x86: Implement local_xchg() using CMPXCHG without the LOCK prefix locking/percpu-rwsem: Trigger contention tracepoints only if contended locking/rwsem: Make DEBUG_RWSEMS and PREEMPT_RT mutually exclusive locking/rwsem: Clarify that RWSEM_READER_OWNED is just a hint locking/mutex: Simplify <linux/mutex.h> locking/qspinlock: Fix 'wait_early' set but not used warning locking/atomic: scripts: Clarify ordering of conditional atomics

Linus Torvalds committed 2 years ago

Commit a5b1a012 parents b040240 ce3576e17 files · +154 −49Browse files

Unified · Split

17 files

arch/x86/include/asm/local.h +14 −2
include/linux/atomic/atomic-arch-fallback.h +37 −9
include/linux/atomic/atomic-instrumented.h +55 −13
include/linux/atomic/atomic-long.h +19 −5
include/linux/mutex.h +2 −6
kernel/locking/percpu-rwsem.c +8 −3
kernel/locking/qspinlock_paravirt.h +1 −1
kernel/locking/rtmutex.c +5 −4
kernel/locking/rwsem.c +3 −3
lib/Kconfig.debug +2 −2
scripts/atomic/kerneldoc/add_unless +1 −0
scripts/atomic/kerneldoc/cmpxchg +1 −0
scripts/atomic/kerneldoc/dec_if_positive +1 −0
scripts/atomic/kerneldoc/dec_unless_positive +1 −0
scripts/atomic/kerneldoc/inc_not_zero +1 −0
scripts/atomic/kerneldoc/inc_unless_negative +1 −0
scripts/atomic/kerneldoc/try_cmpxchg +2 −1

arch/x86/include/asm/local.h+14−2

@@ -131,8 +131,20 @@ static inline bool local_try_cmpxchg(local_t l, long old, long new) · 130 unmodified lines
131	(typeof(l->a.counter) *) old, new);	131	(typeof(l->a.counter) *) old, new);
132	}	132	}
133		133
134	/* Always has a lock prefix */	134	/*
135	#define local_xchg(l, n) (xchg(&((l)->a.counter), (n)))	135	* Implement local_xchg using CMPXCHG instruction without the LOCK prefix.
		136	* XCHG is expensive due to the implied LOCK prefix. The processor
		137	* cannot prefetch cachelines if XCHG is used.
		138	*/
		139	static __always_inline long
		140	local_xchg(local_t *l, long n)
		141	{
		142	long c = local_read(l);
		143
		144	do { } while (!local_try_cmpxchg(l, &c, n));
		145
		146	return c;
		147	}
136		148
137	/**	149	/**
138	* local_add_unless - add unless the number is already a given value	150	* local_add_unless - add unless the number is already a given value

include/linux/atomic/atomic-arch-fallback.h+37−9

  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_cmpxchg() elsewhere.
  *
  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with acquire ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_cmpxchg_acquire() elsewhere.
  *
  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with release ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_cmpxchg_release() elsewhere.
  *
  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with relaxed ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_cmpxchg_relaxed() elsewhere.
  *
  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with full ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_try_cmpxchg() elsewhere.
  *
  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with acquire ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_try_cmpxchg_acquire() elsewhere.
  *
  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with release ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_try_cmpxchg_release() elsewhere.
  *
  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with relaxed ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_try_cmpxchg_relaxed() elsewhere.
  *
  * @u: int value to compare with
  *
  * If (@v != @u), atomically updates @v to (@v + @a) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_fetch_add_unless() elsewhere.
  *
  * @u: int value to compare with
  *
  * If (@v != @u), atomically updates @v to (@v + @a) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_add_unless() elsewhere.
  *
  * @v: pointer to atomic_t
  *
  * If (@v != 0), atomically updates @v to (@v + 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_inc_not_zero() elsewhere.
  *
  * @v: pointer to atomic_t
  *
  * If (@v >= 0), atomically updates @v to (@v + 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_inc_unless_negative() elsewhere.
  *
  * @v: pointer to atomic_t
  *
  * If (@v <= 0), atomically updates @v to (@v - 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_dec_unless_positive() elsewhere.
  *
  * @v: pointer to atomic_t
  *
  * If (@v > 0), atomically updates @v to (@v - 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_dec_if_positive() elsewhere.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic64_cmpxchg() elsewhere.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with acquire ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic64_cmpxchg_acquire() elsewhere.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with release ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic64_cmpxchg_release() elsewhere.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with relaxed ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic64_cmpxchg_relaxed() elsewhere.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with full ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic64_try_cmpxchg() elsewhere.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with acquire ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic64_try_cmpxchg_acquire() elsewhere.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with release ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic64_try_cmpxchg_release() elsewhere.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with relaxed ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic64_try_cmpxchg_relaxed() elsewhere.
  *
  * @u: s64 value to compare with
  *
  * If (@v != @u), atomically updates @v to (@v + @a) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic64_fetch_add_unless() elsewhere.
  *
  * @u: s64 value to compare with
  *
  * If (@v != @u), atomically updates @v to (@v + @a) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic64_add_unless() elsewhere.
  *
  * @v: pointer to atomic64_t
  *
  * If (@v != 0), atomically updates @v to (@v + 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic64_inc_not_zero() elsewhere.
  *
  * @v: pointer to atomic64_t
  *
  * If (@v >= 0), atomically updates @v to (@v + 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic64_inc_unless_negative() elsewhere.
  *
  * @v: pointer to atomic64_t
  *
  * If (@v <= 0), atomically updates @v to (@v - 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic64_dec_unless_positive() elsewhere.
  *
  * @v: pointer to atomic64_t
  *
  * If (@v > 0), atomically updates @v to (@v - 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic64_dec_if_positive() elsewhere.
  *
 }
 #endif /* _LINUX_ATOMIC_FALLBACK_H */
-// eec048affea735b8464f58e6d96992101f8f85f1
+// 14850c0b0db20c62fdc78ccd1d42b98b88d76331

include/linux/atomic/atomic-instrumented.h+55−13

  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_cmpxchg() there.
  *
  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with acquire ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_cmpxchg_acquire() there.
  *
  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with release ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_cmpxchg_release() there.
  *
  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with relaxed ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_cmpxchg_relaxed() there.
  *
  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with full ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_try_cmpxchg() there.
  *
  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with acquire ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_try_cmpxchg_acquire() there.
  *
  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with release ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_try_cmpxchg_release() there.
  *
  * @new: int value to assign
  *
  * If (@v == @old), atomically updates @v to @new with relaxed ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_try_cmpxchg_relaxed() there.
  *
  * @u: int value to compare with
  *
  * If (@v != @u), atomically updates @v to (@v + @a) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_fetch_add_unless() there.
  *
  * @u: int value to compare with
  *
  * If (@v != @u), atomically updates @v to (@v + @a) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_add_unless() there.
  *
  * @v: pointer to atomic_t
  *
  * If (@v != 0), atomically updates @v to (@v + 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_inc_not_zero() there.
  *
  * @v: pointer to atomic_t
  *
  * If (@v >= 0), atomically updates @v to (@v + 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_inc_unless_negative() there.
  *
  * @v: pointer to atomic_t
  *
  * If (@v <= 0), atomically updates @v to (@v - 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_dec_unless_positive() there.
  *
  * @v: pointer to atomic_t
  *
  * If (@v > 0), atomically updates @v to (@v - 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_dec_if_positive() there.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic64_cmpxchg() there.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with acquire ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic64_cmpxchg_acquire() there.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with release ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic64_cmpxchg_release() there.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with relaxed ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic64_cmpxchg_relaxed() there.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with full ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic64_try_cmpxchg() there.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with acquire ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic64_try_cmpxchg_acquire() there.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with release ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic64_try_cmpxchg_release() there.
  *
  * @new: s64 value to assign
  *
  * If (@v == @old), atomically updates @v to @new with relaxed ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic64_try_cmpxchg_relaxed() there.
  *
  * @u: s64 value to compare with
  *
  * If (@v != @u), atomically updates @v to (@v + @a) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic64_fetch_add_unless() there.
  *
  * @u: s64 value to compare with
  *
  * If (@v != @u), atomically updates @v to (@v + @a) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic64_add_unless() there.
  *
  * @v: pointer to atomic64_t
  *
  * If (@v != 0), atomically updates @v to (@v + 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic64_inc_not_zero() there.
  *
  * @v: pointer to atomic64_t
  *
  * If (@v >= 0), atomically updates @v to (@v + 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic64_inc_unless_negative() there.
  *
  * @v: pointer to atomic64_t
  *
  * If (@v <= 0), atomically updates @v to (@v - 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic64_dec_unless_positive() there.
  *
  * @v: pointer to atomic64_t
  *
  * If (@v > 0), atomically updates @v to (@v - 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic64_dec_if_positive() there.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_long_cmpxchg() there.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with acquire ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_long_cmpxchg_acquire() there.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with release ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_long_cmpxchg_release() there.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with relaxed ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_long_cmpxchg_relaxed() there.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with full ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_long_try_cmpxchg() there.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with acquire ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_long_try_cmpxchg_acquire() there.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with release ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_long_try_cmpxchg_release() there.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with relaxed ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_long_try_cmpxchg_relaxed() there.
  *
  * @u: long value to compare with
  *
  * If (@v != @u), atomically updates @v to (@v + @a) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_long_fetch_add_unless() there.
  *
  * @u: long value to compare with
  *
  * If (@v != @u), atomically updates @v to (@v + @a) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_long_add_unless() there.
  *
  * @v: pointer to atomic_long_t
  *
  * If (@v != 0), atomically updates @v to (@v + 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_long_inc_not_zero() there.
  *
  * @v: pointer to atomic_long_t
  *
  * If (@v >= 0), atomically updates @v to (@v + 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_long_inc_unless_negative() there.
  *
  * @v: pointer to atomic_long_t
  *
  * If (@v <= 0), atomically updates @v to (@v - 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_long_dec_unless_positive() there.
  *
  * @v: pointer to atomic_long_t
  *
  * If (@v > 0), atomically updates @v to (@v - 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Unsafe to use in noinstr code; use raw_atomic_long_dec_if_positive() there.
  *
 #endif /* _LINUX_ATOMIC_INSTRUMENTED_H */
-// 2cc4bc990fef44d3836ec108f11b610f3f438184
+// ce5b65e0f1f8a276268b667194581d24bed219d4

include/linux/atomic/atomic-long.h+19−5

  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_long_cmpxchg() elsewhere.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with acquire ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_long_cmpxchg_acquire() elsewhere.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with release ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_long_cmpxchg_release() elsewhere.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with relaxed ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_long_cmpxchg_relaxed() elsewhere.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with full ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_long_try_cmpxchg() elsewhere.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with acquire ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_long_try_cmpxchg_acquire() elsewhere.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with release ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_long_try_cmpxchg_release() elsewhere.
  *
  * @new: long value to assign
  *
  * If (@v == @old), atomically updates @v to @new with relaxed ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_long_try_cmpxchg_relaxed() elsewhere.
  *
  * @u: long value to compare with
  *
  * If (@v != @u), atomically updates @v to (@v + @a) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_long_fetch_add_unless() elsewhere.
  *
  * @u: long value to compare with
  *
  * If (@v != @u), atomically updates @v to (@v + @a) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_long_add_unless() elsewhere.
  *
  * @v: pointer to atomic_long_t
  *
  * If (@v != 0), atomically updates @v to (@v + 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_long_inc_not_zero() elsewhere.
  *
  * @v: pointer to atomic_long_t
  *
  * If (@v >= 0), atomically updates @v to (@v + 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_long_inc_unless_negative() elsewhere.
  *
  * @v: pointer to atomic_long_t
  *
  * If (@v <= 0), atomically updates @v to (@v - 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_long_dec_unless_positive() elsewhere.
  *
  * @v: pointer to atomic_long_t
  *
  * If (@v > 0), atomically updates @v to (@v - 1) with full ordering.
+ * Otherwise, @v is not modified and relaxed ordering is provided.
  *
  * Safe to use in noinstr code; prefer atomic_long_dec_if_positive() elsewhere.
  *
 }
 #endif /* _LINUX_ATOMIC_LONG_H */
-// 4ef23f98c73cff96d239896175fd26b10b88899e
+// 1c4a26fc77f345342953770ebe3c4d08e7ce2f9a

include/linux/mutex.h+2−6

 # define __DEP_MAP_MUTEX_INITIALIZER(lockname)
 #endif
-#ifndef CONFIG_PREEMPT_RT
 #ifdef CONFIG_DEBUG_MUTEXES
-#define __DEBUG_MUTEX_INITIALIZER(lockname)				\
+# define __DEBUG_MUTEX_INITIALIZER(lockname)				\
 	, .magic = &lockname
 extern void mutex_destroy(struct mutex *lock);
 #endif
+#ifndef CONFIG_PREEMPT_RT
 /**
  * mutex_init - initialize the mutex
  * @mutex: the mutex to be initialized
 extern void __mutex_rt_init(struct mutex *lock, const char *name,
 			    struct lock_class_key *key);
-extern int mutex_trylock(struct mutex *lock);
-static inline void mutex_destroy(struct mutex *lock) { }
 #define mutex_is_locked(l)	rt_mutex_base_is_locked(&(l)->rtmutex)

kernel/locking/percpu-rwsem.c+8−3

 void __sched percpu_down_write(struct percpu_rw_semaphore *sem)
 {
+	bool contended = false;
 	might_sleep();
 	rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);
-	trace_contention_begin(sem, LCB_F_PERCPU | LCB_F_WRITE);
 	/* Notify readers to take the slow path. */
 	rcu_sync_enter(&sem->rss);
 	 * Try set sem->block; this provides writer-writer exclusion.
 	 * Having sem->block set makes new readers block.
 	 */
-	if (!__percpu_down_write_trylock(sem))
+	if (!__percpu_down_write_trylock(sem)) {
+		trace_contention_begin(sem, LCB_F_PERCPU | LCB_F_WRITE);
 		percpu_rwsem_wait(sem, /* .reader = */ false);
+		contended = true;
+	}
 	/* smp_mb() implied by __percpu_down_write_trylock() on success -- D matches A */
 	/* Wait for all active readers to complete. */
 	rcuwait_wait_event(&sem->writer, readers_active_check(sem), TASK_UNINTERRUPTIBLE);
-	trace_contention_end(sem, 0);
+	if (contended)
+		trace_contention_end(sem, 0);
 }
 EXPORT_SYMBOL_GPL(percpu_down_write);

kernel/locking/qspinlock_paravirt.h+1−1

 {
 	struct pv_node *pn = (struct pv_node *)node;
 	struct pv_node *pp = (struct pv_node *)prev;
+	bool __maybe_unused wait_early;
 	int loop;
-	bool wait_early;
 	for (;;) {
 		for (wait_early = false, loop = SPIN_THRESHOLD; loop; loop--) {

kernel/locking/rtmutex.c+5−4

  */
 static __always_inline void mark_rt_mutex_waiters(struct rt_mutex_base *lock)
 {
-	unsigned long owner, *p = (unsigned long *) &lock->owner;
+	unsigned long *p = (unsigned long *) &lock->owner;
+	unsigned long owner, new;
+	owner = READ_ONCE(*p);
 	do {
-		owner = *p;
+		new = owner | RT_MUTEX_HAS_WAITERS;
-	} while (cmpxchg_relaxed(p, owner,
+	} while (!try_cmpxchg_relaxed(p, &owner, new));
-				 owner | RT_MUTEX_HAS_WAITERS) != owner);
 	/*
 	 * The cmpxchg loop above is relaxed to avoid back-to-back ACQUIRE

kernel/locking/rwsem.c+3−3

@@ -35,7 +35,7 @@ · 34 unmodified lines
35	/*	35	/*
36	* The least significant 2 bits of the owner value has the following	36	* The least significant 2 bits of the owner value has the following
37	* meanings when set.	37	* meanings when set.
38	* - Bit 0: RWSEM_READER_OWNED - The rwsem is owned by readers	38	* - Bit 0: RWSEM_READER_OWNED - rwsem may be owned by readers (just a hint)
39	* - Bit 1: RWSEM_NONSPINNABLE - Cannot spin on a reader-owned lock	39	* - Bit 1: RWSEM_NONSPINNABLE - Cannot spin on a reader-owned lock
40	*	40	*
41	* When the rwsem is reader-owned and a spinning writer has timed out,	41	* When the rwsem is reader-owned and a spinning writer has timed out,
@@ -1002,8 +1002,8 @@ rwsem_down_read_slowpath(struct rw_semaphore *sem, long count, unsigned int stat · 960 unmodified lines
1002		1002
1003	/*	1003	/*
1004	* To prevent a constant stream of readers from starving a sleeping	1004	* To prevent a constant stream of readers from starving a sleeping
1005	* waiter, don't attempt optimistic lock stealing if the lock is	1005	* writer, don't attempt optimistic lock stealing if the lock is
1006	* currently owned by readers.	1006	* very likely owned by readers.
1007	*/	1007	*/
1008	if ((atomic_long_read(&sem->owner) & RWSEM_READER_OWNED) &&	1008	if ((atomic_long_read(&sem->owner) & RWSEM_READER_OWNED) &&
1009	(rcnt > 1) && !(count & RWSEM_WRITER_LOCKED))	1009	(rcnt > 1) && !(count & RWSEM_WRITER_LOCKED))

lib/Kconfig.debug+2−2

@@ -1303,7 +1303,7 @@ config PROVE_LOCKING · 1302 unmodified lines
1303	select DEBUG_SPINLOCK	1303	select DEBUG_SPINLOCK
1304	select DEBUG_MUTEXES if !PREEMPT_RT	1304	select DEBUG_MUTEXES if !PREEMPT_RT
1305	select DEBUG_RT_MUTEXES if RT_MUTEXES	1305	select DEBUG_RT_MUTEXES if RT_MUTEXES
1306	select DEBUG_RWSEMS	1306	select DEBUG_RWSEMS if !PREEMPT_RT
1307	select DEBUG_WW_MUTEX_SLOWPATH	1307	select DEBUG_WW_MUTEX_SLOWPATH
1308	select DEBUG_LOCK_ALLOC	1308	select DEBUG_LOCK_ALLOC
1309	select PREEMPT_COUNT if !ARCH_NO_PREEMPT	1309	select PREEMPT_COUNT if !ARCH_NO_PREEMPT
@@ -1426,7 +1426,7 @@ config DEBUG_WW_MUTEX_SLOWPATH · 116 unmodified lines
1426		1426
1427	config DEBUG_RWSEMS	1427	config DEBUG_RWSEMS
1428	bool "RW Semaphore debugging: basic checks"	1428	bool "RW Semaphore debugging: basic checks"
1429	depends on DEBUG_KERNEL	1429	depends on DEBUG_KERNEL && !PREEMPT_RT
1430	help	1430	help
1431	This debugging feature allows mismatched rw semaphore locks	1431	This debugging feature allows mismatched rw semaphore locks
1432	and unlocks to be detected and reported.	1432	and unlocks to be detected and reported.

scripts/atomic/kerneldoc/add_unless+1−0

@@ -10,6 +10,7 @@ cat <<EOF · 9 unmodified lines
10	* @u: ${int} value to compare with	10	* @u: ${int} value to compare with
11	*	11	*
12	* If (@v != @u), atomically updates @v to (@v + @a) with ${desc_order} ordering.	12	* If (@v != @u), atomically updates @v to (@v + @a) with ${desc_order} ordering.
		13	* Otherwise, @v is not modified and relaxed ordering is provided.
13	*	14	*
14	* ${desc_noinstr}	15	* ${desc_noinstr}
15	*	16	*

scripts/atomic/kerneldoc/cmpxchg+1−0

@@ -6,6 +6,7 @@ cat <<EOF · 5 unmodified lines
6	* @new: ${int} value to assign	6	* @new: ${int} value to assign
7	*	7	*
8	* If (@v == @old), atomically updates @v to @new with ${desc_order} ordering.	8	* If (@v == @old), atomically updates @v to @new with ${desc_order} ordering.
		9	* Otherwise, @v is not modified and relaxed ordering is provided.
9	*	10	*
10	* ${desc_noinstr}	11	* ${desc_noinstr}
11	*	12	*

scripts/atomic/kerneldoc/dec_if_positive+1−0

@@ -4,6 +4,7 @@ cat <<EOF · 3 unmodified lines
4	* @v: pointer to ${atomic}_t	4	* @v: pointer to ${atomic}_t
5	*	5	*
6	* If (@v > 0), atomically updates @v to (@v - 1) with ${desc_order} ordering.	6	* If (@v > 0), atomically updates @v to (@v - 1) with ${desc_order} ordering.
		7	* Otherwise, @v is not modified and relaxed ordering is provided.
7	*	8	*
8	* ${desc_noinstr}	9	* ${desc_noinstr}
9	*	10	*

scripts/atomic/kerneldoc/dec_unless_positive+1−0

@@ -4,6 +4,7 @@ cat <<EOF · 3 unmodified lines
4	* @v: pointer to ${atomic}_t	4	* @v: pointer to ${atomic}_t
5	*	5	*
6	* If (@v <= 0), atomically updates @v to (@v - 1) with ${desc_order} ordering.	6	* If (@v <= 0), atomically updates @v to (@v - 1) with ${desc_order} ordering.
		7	* Otherwise, @v is not modified and relaxed ordering is provided.
7	*	8	*
8	* ${desc_noinstr}	9	* ${desc_noinstr}
9	*	10	*

scripts/atomic/kerneldoc/inc_not_zero+1−0

@@ -4,6 +4,7 @@ cat <<EOF · 3 unmodified lines
4	* @v: pointer to ${atomic}_t	4	* @v: pointer to ${atomic}_t
5	*	5	*
6	* If (@v != 0), atomically updates @v to (@v + 1) with ${desc_order} ordering.	6	* If (@v != 0), atomically updates @v to (@v + 1) with ${desc_order} ordering.
		7	* Otherwise, @v is not modified and relaxed ordering is provided.
7	*	8	*
8	* ${desc_noinstr}	9	* ${desc_noinstr}
9	*	10	*

scripts/atomic/kerneldoc/inc_unless_negative+1−0

@@ -4,6 +4,7 @@ cat <<EOF · 3 unmodified lines
4	* @v: pointer to ${atomic}_t	4	* @v: pointer to ${atomic}_t
5	*	5	*
6	* If (@v >= 0), atomically updates @v to (@v + 1) with ${desc_order} ordering.	6	* If (@v >= 0), atomically updates @v to (@v + 1) with ${desc_order} ordering.
		7	* Otherwise, @v is not modified and relaxed ordering is provided.
7	*	8	*
8	* ${desc_noinstr}	9	* ${desc_noinstr}
9	*	10	*

scripts/atomic/kerneldoc/try_cmpxchg+2−1

  * @new: ${int} value to assign
  *
  * If (@v == @old), atomically updates @v to @new with ${desc_order} ordering.
- * Otherwise, updates @old to the current value of @v.
+ * Otherwise, @v is not modified, @old is updated to the current value of @v,
+ * and relaxed ordering is provided.
  *
  * ${desc_noinstr}
  *

Merge tag 'locking-core-2024-03-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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