1 files changed, 6 insertions, 275 deletions

diff --git a/kernel/locking/rwsem.h b/kernel/locking/rwsem.h
index 499a9b2bda82..2534ce49f648 100644
--- a/kernel/locking/rwsem.h
+++ b/kernel/locking/rwsem.h
@@ -1,279 +1,10 @@
 /* SPDX-License-Identifier: GPL-2.0 */
-/*
- * The least significant 2 bits of the owner value has the following
- * meanings when set.
- *  - RWSEM_READER_OWNED (bit 0): The rwsem is owned by readers
- *  - RWSEM_ANONYMOUSLY_OWNED (bit 1): The rwsem is anonymously owned,
- *    i.e. the owner(s) cannot be readily determined. It can be reader
- *    owned or the owning writer is indeterminate.
- *
- * When a writer acquires a rwsem, it puts its task_struct pointer
- * into the owner field. It is cleared after an unlock.
- *
- * When a reader acquires a rwsem, it will also puts its task_struct
- * pointer into the owner field with both the RWSEM_READER_OWNED and
- * RWSEM_ANONYMOUSLY_OWNED bits set. On unlock, the owner field will
- * largely be left untouched. So for a free or reader-owned rwsem,
- * the owner value may contain information about the last reader that
- * acquires the rwsem. The anonymous bit is set because that particular
- * reader may or may not still own the lock.
- *
- * That information may be helpful in debugging cases where the system
- * seems to hang on a reader owned rwsem especially if only one reader
- * is involved. Ideally we would like to track all the readers that own
- * a rwsem, but the overhead is simply too big.
- */
-#include "lock_events.h"
 
-#define RWSEM_READER_OWNED	(1UL << 0)
-#define RWSEM_ANONYMOUSLY_OWNED	(1UL << 1)
+#ifndef __INTERNAL_RWSEM_H
+#define __INTERNAL_RWSEM_H
+#include <linux/rwsem.h>
 
-#ifdef CONFIG_DEBUG_RWSEMS
-# define DEBUG_RWSEMS_WARN_ON(c, sem)	do {			\
-	if (!debug_locks_silent &&				\
-	    WARN_ONCE(c, "DEBUG_RWSEMS_WARN_ON(%s): count = 0x%lx, owner = 0x%lx, curr 0x%lx, list %sempty\n",\
-		#c, atomic_long_read(&(sem)->count),		\
-		(long)((sem)->owner), (long)current,		\
-		list_empty(&(sem)->wait_list) ? "" : "not "))	\
-			debug_locks_off();			\
-	} while (0)
-#else
-# define DEBUG_RWSEMS_WARN_ON(c, sem)
-#endif
+extern void __down_read(struct rw_semaphore *sem);
+extern void __up_read(struct rw_semaphore *sem);
 
-/*
- * The definition of the atomic counter in the semaphore:
- *
- * Bit  0   - writer locked bit
- * Bit  1   - waiters present bit
- * Bits 2-7 - reserved
- * Bits 8-X - 24-bit (32-bit) or 56-bit reader count
- *
- * atomic_long_fetch_add() is used to obtain reader lock, whereas
- * atomic_long_cmpxchg() will be used to obtain writer lock.
- */
-#define RWSEM_WRITER_LOCKED	(1UL << 0)
-#define RWSEM_FLAG_WAITERS	(1UL << 1)
-#define RWSEM_READER_SHIFT	8
-#define RWSEM_READER_BIAS	(1UL << RWSEM_READER_SHIFT)
-#define RWSEM_READER_MASK	(~(RWSEM_READER_BIAS - 1))
-#define RWSEM_WRITER_MASK	RWSEM_WRITER_LOCKED
-#define RWSEM_LOCK_MASK		(RWSEM_WRITER_MASK|RWSEM_READER_MASK)
-#define RWSEM_READ_FAILED_MASK	(RWSEM_WRITER_MASK|RWSEM_FLAG_WAITERS)
-
-/*
- * All writes to owner are protected by WRITE_ONCE() to make sure that
- * store tearing can't happen as optimistic spinners may read and use
- * the owner value concurrently without lock. Read from owner, however,
- * may not need READ_ONCE() as long as the pointer value is only used
- * for comparison and isn't being dereferenced.
- */
-static inline void rwsem_set_owner(struct rw_semaphore *sem)
-{
-	WRITE_ONCE(sem->owner, current);
-}
-
-static inline void rwsem_clear_owner(struct rw_semaphore *sem)
-{
-	WRITE_ONCE(sem->owner, NULL);
-}
-
-/*
- * The task_struct pointer of the last owning reader will be left in
- * the owner field.
- *
- * Note that the owner value just indicates the task has owned the rwsem
- * previously, it may not be the real owner or one of the real owners
- * anymore when that field is examined, so take it with a grain of salt.
- */
-static inline void __rwsem_set_reader_owned(struct rw_semaphore *sem,
-					    struct task_struct *owner)
-{
-	unsigned long val = (unsigned long)owner | RWSEM_READER_OWNED
-						 | RWSEM_ANONYMOUSLY_OWNED;
-
-	WRITE_ONCE(sem->owner, (struct task_struct *)val);
-}
-
-static inline void rwsem_set_reader_owned(struct rw_semaphore *sem)
-{
-	__rwsem_set_reader_owned(sem, current);
-}
-
-/*
- * Return true if the a rwsem waiter can spin on the rwsem's owner
- * and steal the lock, i.e. the lock is not anonymously owned.
- * N.B. !owner is considered spinnable.
- */
-static inline bool is_rwsem_owner_spinnable(struct task_struct *owner)
-{
-	return !((unsigned long)owner & RWSEM_ANONYMOUSLY_OWNED);
-}
-
-/*
- * Return true if rwsem is owned by an anonymous writer or readers.
- */
-static inline bool rwsem_has_anonymous_owner(struct task_struct *owner)
-{
-	return (unsigned long)owner & RWSEM_ANONYMOUSLY_OWNED;
-}
-
-#ifdef CONFIG_DEBUG_RWSEMS
-/*
- * With CONFIG_DEBUG_RWSEMS configured, it will make sure that if there
- * is a task pointer in owner of a reader-owned rwsem, it will be the
- * real owner or one of the real owners. The only exception is when the
- * unlock is done by up_read_non_owner().
- */
-static inline void rwsem_clear_reader_owned(struct rw_semaphore *sem)
-{
-	unsigned long val = (unsigned long)current | RWSEM_READER_OWNED
-						   | RWSEM_ANONYMOUSLY_OWNED;
-	if (READ_ONCE(sem->owner) == (struct task_struct *)val)
-		cmpxchg_relaxed((unsigned long *)&sem->owner, val,
-				RWSEM_READER_OWNED | RWSEM_ANONYMOUSLY_OWNED);
-}
-#else
-static inline void rwsem_clear_reader_owned(struct rw_semaphore *sem)
-{
-}
-#endif
-
-extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem);
-extern struct rw_semaphore *rwsem_down_read_failed_killable(struct rw_semaphore *sem);
-extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem);
-extern struct rw_semaphore *rwsem_down_write_failed_killable(struct rw_semaphore *sem);
-extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem);
-extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem);
-
-/*
- * lock for reading
- */
-static inline void __down_read(struct rw_semaphore *sem)
-{
-	if (unlikely(atomic_long_fetch_add_acquire(RWSEM_READER_BIAS,
-			&sem->count) & RWSEM_READ_FAILED_MASK)) {
-		rwsem_down_read_failed(sem);
-		DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner &
-					RWSEM_READER_OWNED), sem);
-	} else {
-		rwsem_set_reader_owned(sem);
-	}
-}
-
-static inline int __down_read_killable(struct rw_semaphore *sem)
-{
-	if (unlikely(atomic_long_fetch_add_acquire(RWSEM_READER_BIAS,
-			&sem->count) & RWSEM_READ_FAILED_MASK)) {
-		if (IS_ERR(rwsem_down_read_failed_killable(sem)))
-			return -EINTR;
-		DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner &
-					RWSEM_READER_OWNED), sem);
-	} else {
-		rwsem_set_reader_owned(sem);
-	}
-	return 0;
-}
-
-static inline int __down_read_trylock(struct rw_semaphore *sem)
-{
-	/*
-	 * Optimize for the case when the rwsem is not locked at all.
-	 */
-	long tmp = RWSEM_UNLOCKED_VALUE;
-
-	lockevent_inc(rwsem_rtrylock);
-	do {
-		if (atomic_long_try_cmpxchg_acquire(&sem->count, &tmp,
-					tmp + RWSEM_READER_BIAS)) {
-			rwsem_set_reader_owned(sem);
-			return 1;
-		}
-	} while (!(tmp & RWSEM_READ_FAILED_MASK));
-	return 0;
-}
-
-/*
- * lock for writing
- */
-static inline void __down_write(struct rw_semaphore *sem)
-{
-	if (unlikely(atomic_long_cmpxchg_acquire(&sem->count, 0,
-						 RWSEM_WRITER_LOCKED)))
-		rwsem_down_write_failed(sem);
-	rwsem_set_owner(sem);
-}
-
-static inline int __down_write_killable(struct rw_semaphore *sem)
-{
-	if (unlikely(atomic_long_cmpxchg_acquire(&sem->count, 0,
-						 RWSEM_WRITER_LOCKED)))
-		if (IS_ERR(rwsem_down_write_failed_killable(sem)))
-			return -EINTR;
-	rwsem_set_owner(sem);
-	return 0;
-}
-
-static inline int __down_write_trylock(struct rw_semaphore *sem)
-{
-	long tmp;
-
-	lockevent_inc(rwsem_wtrylock);
-	tmp = atomic_long_cmpxchg_acquire(&sem->count, RWSEM_UNLOCKED_VALUE,
-					  RWSEM_WRITER_LOCKED);
-	if (tmp == RWSEM_UNLOCKED_VALUE) {
-		rwsem_set_owner(sem);
-		return true;
-	}
-	return false;
-}
-
-/*
- * unlock after reading
- */
-static inline void __up_read(struct rw_semaphore *sem)
-{
-	long tmp;
-
-	DEBUG_RWSEMS_WARN_ON(!((unsigned long)sem->owner & RWSEM_READER_OWNED),
-				sem);
-	rwsem_clear_reader_owned(sem);
-	tmp = atomic_long_add_return_release(-RWSEM_READER_BIAS, &sem->count);
-	if (unlikely((tmp & (RWSEM_LOCK_MASK|RWSEM_FLAG_WAITERS))
-			== RWSEM_FLAG_WAITERS))
-		rwsem_wake(sem);
-}
-
-/*
- * unlock after writing
- */
-static inline void __up_write(struct rw_semaphore *sem)
-{
-	DEBUG_RWSEMS_WARN_ON(sem->owner != current, sem);
-	rwsem_clear_owner(sem);
-	if (unlikely(atomic_long_fetch_add_release(-RWSEM_WRITER_LOCKED,
-			&sem->count) & RWSEM_FLAG_WAITERS))
-		rwsem_wake(sem);
-}
-
-/*
- * downgrade write lock to read lock
- */
-static inline void __downgrade_write(struct rw_semaphore *sem)
-{
-	long tmp;
-
-	/*
-	 * When downgrading from exclusive to shared ownership,
-	 * anything inside the write-locked region cannot leak
-	 * into the read side. In contrast, anything in the
-	 * read-locked region is ok to be re-ordered into the
-	 * write side. As such, rely on RELEASE semantics.
-	 */
-	DEBUG_RWSEMS_WARN_ON(sem->owner != current, sem);
-	tmp = atomic_long_fetch_add_release(
-		-RWSEM_WRITER_LOCKED+RWSEM_READER_BIAS, &sem->count);
-	rwsem_set_reader_owned(sem);
-	if (tmp & RWSEM_FLAG_WAITERS)
-		rwsem_downgrade_wake(sem);
-}
+#endif /* __INTERNAL_RWSEM_H */