v4.19.13 snapshot.
diff --git a/include/linux/mutex.h b/include/linux/mutex.h
new file mode 100644
index 0000000..3093dd1
--- /dev/null
+++ b/include/linux/mutex.h
@@ -0,0 +1,232 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Mutexes: blocking mutual exclusion locks
+ *
+ * started by Ingo Molnar:
+ *
+ * Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ *
+ * This file contains the main data structure and API definitions.
+ */
+#ifndef __LINUX_MUTEX_H
+#define __LINUX_MUTEX_H
+
+#include <asm/current.h>
+#include <linux/list.h>
+#include <linux/spinlock_types.h>
+#include <linux/lockdep.h>
+#include <linux/atomic.h>
+#include <asm/processor.h>
+#include <linux/osq_lock.h>
+#include <linux/debug_locks.h>
+
+struct ww_acquire_ctx;
+
+/*
+ * Simple, straightforward mutexes with strict semantics:
+ *
+ * - only one task can hold the mutex at a time
+ * - only the owner can unlock the mutex
+ * - multiple unlocks are not permitted
+ * - recursive locking is not permitted
+ * - a mutex object must be initialized via the API
+ * - a mutex object must not be initialized via memset or copying
+ * - task may not exit with mutex held
+ * - memory areas where held locks reside must not be freed
+ * - held mutexes must not be reinitialized
+ * - mutexes may not be used in hardware or software interrupt
+ * contexts such as tasklets and timers
+ *
+ * These semantics are fully enforced when DEBUG_MUTEXES is
+ * enabled. Furthermore, besides enforcing the above rules, the mutex
+ * debugging code also implements a number of additional features
+ * that make lock debugging easier and faster:
+ *
+ * - uses symbolic names of mutexes, whenever they are printed in debug output
+ * - point-of-acquire tracking, symbolic lookup of function names
+ * - list of all locks held in the system, printout of them
+ * - owner tracking
+ * - detects self-recursing locks and prints out all relevant info
+ * - detects multi-task circular deadlocks and prints out all affected
+ * locks and tasks (and only those tasks)
+ */
+struct mutex {
+ atomic_long_t owner;
+ spinlock_t wait_lock;
+#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
+ struct optimistic_spin_queue osq; /* Spinner MCS lock */
+#endif
+ struct list_head wait_list;
+#ifdef CONFIG_DEBUG_MUTEXES
+ void *magic;
+#endif
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+ struct lockdep_map dep_map;
+#endif
+};
+
+/*
+ * Internal helper function; C doesn't allow us to hide it :/
+ *
+ * DO NOT USE (outside of mutex code).
+ */
+static inline struct task_struct *__mutex_owner(struct mutex *lock)
+{
+ return (struct task_struct *)(atomic_long_read(&lock->owner) & ~0x07);
+}
+
+/*
+ * This is the control structure for tasks blocked on mutex,
+ * which resides on the blocked task's kernel stack:
+ */
+struct mutex_waiter {
+ struct list_head list;
+ struct task_struct *task;
+ struct ww_acquire_ctx *ww_ctx;
+#ifdef CONFIG_DEBUG_MUTEXES
+ void *magic;
+#endif
+};
+
+#ifdef CONFIG_DEBUG_MUTEXES
+
+#define __DEBUG_MUTEX_INITIALIZER(lockname) \
+ , .magic = &lockname
+
+extern void mutex_destroy(struct mutex *lock);
+
+#else
+
+# define __DEBUG_MUTEX_INITIALIZER(lockname)
+
+static inline void mutex_destroy(struct mutex *lock) {}
+
+#endif
+
+/**
+ * mutex_init - initialize the mutex
+ * @mutex: the mutex to be initialized
+ *
+ * Initialize the mutex to unlocked state.
+ *
+ * It is not allowed to initialize an already locked mutex.
+ */
+#define mutex_init(mutex) \
+do { \
+ static struct lock_class_key __key; \
+ \
+ __mutex_init((mutex), #mutex, &__key); \
+} while (0)
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+# define __DEP_MAP_MUTEX_INITIALIZER(lockname) \
+ , .dep_map = { .name = #lockname }
+#else
+# define __DEP_MAP_MUTEX_INITIALIZER(lockname)
+#endif
+
+#define __MUTEX_INITIALIZER(lockname) \
+ { .owner = ATOMIC_LONG_INIT(0) \
+ , .wait_lock = __SPIN_LOCK_UNLOCKED(lockname.wait_lock) \
+ , .wait_list = LIST_HEAD_INIT(lockname.wait_list) \
+ __DEBUG_MUTEX_INITIALIZER(lockname) \
+ __DEP_MAP_MUTEX_INITIALIZER(lockname) }
+
+#define DEFINE_MUTEX(mutexname) \
+ struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
+
+extern void __mutex_init(struct mutex *lock, const char *name,
+ struct lock_class_key *key);
+
+/**
+ * mutex_is_locked - is the mutex locked
+ * @lock: the mutex to be queried
+ *
+ * Returns true if the mutex is locked, false if unlocked.
+ */
+static inline bool mutex_is_locked(struct mutex *lock)
+{
+ return __mutex_owner(lock) != NULL;
+}
+
+/*
+ * See kernel/locking/mutex.c for detailed documentation of these APIs.
+ * Also see Documentation/locking/mutex-design.txt.
+ */
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
+extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
+
+extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
+ unsigned int subclass);
+extern int __must_check mutex_lock_killable_nested(struct mutex *lock,
+ unsigned int subclass);
+extern void mutex_lock_io_nested(struct mutex *lock, unsigned int subclass);
+
+#define mutex_lock(lock) mutex_lock_nested(lock, 0)
+#define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)
+#define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0)
+#define mutex_lock_io(lock) mutex_lock_io_nested(lock, 0)
+
+#define mutex_lock_nest_lock(lock, nest_lock) \
+do { \
+ typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
+ _mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \
+} while (0)
+
+#else
+extern void mutex_lock(struct mutex *lock);
+extern int __must_check mutex_lock_interruptible(struct mutex *lock);
+extern int __must_check mutex_lock_killable(struct mutex *lock);
+extern void mutex_lock_io(struct mutex *lock);
+
+# define mutex_lock_nested(lock, subclass) mutex_lock(lock)
+# define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
+# define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)
+# define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock)
+# define mutex_lock_io_nested(lock, subclass) mutex_lock(lock)
+#endif
+
+/*
+ * NOTE: mutex_trylock() follows the spin_trylock() convention,
+ * not the down_trylock() convention!
+ *
+ * Returns 1 if the mutex has been acquired successfully, and 0 on contention.
+ */
+extern int mutex_trylock(struct mutex *lock);
+extern void mutex_unlock(struct mutex *lock);
+
+extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
+
+/*
+ * These values are chosen such that FAIL and SUCCESS match the
+ * values of the regular mutex_trylock().
+ */
+enum mutex_trylock_recursive_enum {
+ MUTEX_TRYLOCK_FAILED = 0,
+ MUTEX_TRYLOCK_SUCCESS = 1,
+ MUTEX_TRYLOCK_RECURSIVE,
+};
+
+/**
+ * mutex_trylock_recursive - trylock variant that allows recursive locking
+ * @lock: mutex to be locked
+ *
+ * This function should not be used, _ever_. It is purely for hysterical GEM
+ * raisins, and once those are gone this will be removed.
+ *
+ * Returns:
+ * - MUTEX_TRYLOCK_FAILED - trylock failed,
+ * - MUTEX_TRYLOCK_SUCCESS - lock acquired,
+ * - MUTEX_TRYLOCK_RECURSIVE - we already owned the lock.
+ */
+static inline /* __deprecated */ __must_check enum mutex_trylock_recursive_enum
+mutex_trylock_recursive(struct mutex *lock)
+{
+ if (unlikely(__mutex_owner(lock) == current))
+ return MUTEX_TRYLOCK_RECURSIVE;
+
+ return mutex_trylock(lock);
+}
+
+#endif /* __LINUX_MUTEX_H */