Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/kernel/locking/rwsem.h b/kernel/locking/rwsem.h
index b9d0e72..2534ce4 100644
--- a/kernel/locking/rwsem.h
+++ b/kernel/locking/rwsem.h
@@ -1,87 +1,10 @@
/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * The owner field of the rw_semaphore structure will be set to
- * RWSEM_READER_OWNED when a reader grabs the lock. A writer will clear
- * the owner field when it unlocks. A reader, on the other hand, will
- * not touch the owner field when it unlocks.
- *
- * In essence, the owner field now has the following 4 states:
- * 1) 0
- * - lock is free or the owner hasn't set the field yet
- * 2) RWSEM_READER_OWNED
- * - lock is currently or previously owned by readers (lock is free
- * or not set by owner yet)
- * 3) RWSEM_ANONYMOUSLY_OWNED bit set with some other bits set as well
- * - lock is owned by an anonymous writer, so spinning on the lock
- * owner should be disabled.
- * 4) Other non-zero value
- * - a writer owns the lock and other writers can spin on the lock owner.
- */
-#define RWSEM_ANONYMOUSLY_OWNED (1UL << 0)
-#define RWSEM_READER_OWNED ((struct task_struct *)RWSEM_ANONYMOUSLY_OWNED)
-#ifdef CONFIG_DEBUG_RWSEMS
-# define DEBUG_RWSEMS_WARN_ON(c) DEBUG_LOCKS_WARN_ON(c)
-#else
-# define DEBUG_RWSEMS_WARN_ON(c)
-#endif
+#ifndef __INTERNAL_RWSEM_H
+#define __INTERNAL_RWSEM_H
+#include <linux/rwsem.h>
-#ifdef CONFIG_RWSEM_SPIN_ON_OWNER
-/*
- * 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);
-}
+extern void __down_read(struct rw_semaphore *sem);
+extern void __up_read(struct rw_semaphore *sem);
-static inline void rwsem_clear_owner(struct rw_semaphore *sem)
-{
- WRITE_ONCE(sem->owner, NULL);
-}
-
-static inline void rwsem_set_reader_owned(struct rw_semaphore *sem)
-{
- /*
- * We check the owner value first to make sure that we will only
- * do a write to the rwsem cacheline when it is really necessary
- * to minimize cacheline contention.
- */
- if (READ_ONCE(sem->owner) != RWSEM_READER_OWNED)
- WRITE_ONCE(sem->owner, RWSEM_READER_OWNED);
-}
-
-/*
- * 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;
-}
-#else
-static inline void rwsem_set_owner(struct rw_semaphore *sem)
-{
-}
-
-static inline void rwsem_clear_owner(struct rw_semaphore *sem)
-{
-}
-
-static inline void rwsem_set_reader_owned(struct rw_semaphore *sem)
-{
-}
-#endif
+#endif /* __INTERNAL_RWSEM_H */