// SPDX-License-Identifier: GPL-2.0-only
/*
* kernel/locking/mutex.c
*
* Mutexes: blocking mutual exclusion locks
*
* Started by Ingo Molnar:
*
* Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
*
* Many thanks to Arjan van de Ven, Thomas Gleixner, Steven Rostedt and
* David Howells for suggestions and improvements.
*
* - Adaptive spinning for mutexes by Peter Zijlstra. (Ported to mainline
* from the -rt tree, where it was originally implemented for rtmutexes
* by Steven Rostedt, based on work by Gregory Haskins, Peter Morreale
* and Sven Dietrich.
*
* Also see Documentation/locking/mutex-design.rst.
*/
#include <linux/mutex.h>
#include <linux/ww_mutex.h>
#include <linux/sched/signal.h>
#include <linux/sched/rt.h>
#include <linux/sched/wake_q.h>
#include <linux/sched/debug.h>
#include <linux/export.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/debug_locks.h>
#include <linux/osq_lock.h>
#ifdef CONFIG_DEBUG_MUTEXES
# include "mutex-debug.h"
#else
# include "mutex.h"
#endif
void
__mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key)
{
atomic_long_set(&lock->owner, 0);
spin_lock_init(&lock->wait_lock);
INIT_LIST_HEAD(&lock->wait_list);
#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
osq_lock_init(&lock->osq);
#endif
debug_mutex_init(lock, name, key);
}
EXPORT_SYMBOL(__mutex_init);
/*
* @owner: contains: 'struct task_struct *' to the current lock owner,
* NULL means not owned. Since task_struct pointers are aligned at
* at least L1_CACHE_BYTES, we have low bits to store extra state.
*
* Bit0 indicates a non-empty waiter list; unlock must issue a wakeup.
* Bit1 indicates unlock needs to hand the lock to the top-waiter
* Bit2 indicates handoff has been done and we're waiting for pickup.
*/
#define MUTEX_FLAG_WAITERS 0x01
#define MUTEX_FLAG_HANDOFF 0x02
#define MUTEX_FLAG_PICKUP 0x04
#define MUTEX_FLAGS 0x07
static inline struct task_struct *__owner_task(unsigned long