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     €ЗЖ„ eЯЕїГ 2н    /* SPDX-License-Identifier: GPL-2.0 */
/*
 * Wound/Wait Mutexes: blocking mutual exclusion locks with deadlock avoidance
 *
 * Original mutex implementation started by Ingo Molnar:
 *
 *  Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 *
 * Wait/Die implementation:
 *  Copyright (C) 2013 Canonical Ltd.
 * Choice of algorithm:
 *  Copyright (C) 2018 WMWare Inc.
 *
 * This file contains the main data structure and API definitions.
 */

#ifndef __LINUX_WW_MUTEX_H
#define __LINUX_WW_MUTEX_H

#include <linux/mutex.h>
#include <linux/rtmutex.h>

#if defined(CONFIG_DEBUG_MUTEXES) || \
   (defined(CONFIG_PREEMPT_RT) && defined(CONFIG_DEBUG_RT_MUTEXES))
#define DEBUG_WW_MUTEXES
#endif

#ifndef CONFIG_PREEMPT_RT
#define WW_MUTEX_BASE			mutex
#define ww_mutex_base_init(l,n,k)	__mutex_init(l,n,k)
#define ww_mutex_base_is_locked(b)	mutex_is_locked((b))
#else
#define WW_MUTEX_BASE			rt_mutex
#define ww_mutex_base_init(l,n,k)	__rt_mutex_init(l,n,k)
#define ww_mutex_base_is_locked(b)	rt_mutex_base_is_locked(&(b)->rtmutex)
#endif

struct ww_class {
	atomic_long_t stamp;
	struct lock_class_key acquire_key;
	struct lock_class_key mutex_key;
	const char *acquire_name;
	const char *mutex_name;
	unsigned int is_wait_die;
};

struct ww_mutex {
	struct WW_MUTEX_BASE base;
	struct ww_acquire_ctx *ctx;
#ifdef DEBUG_WW_MUTEXES
	struct ww_class *ww_class;
#endif
};

struct ww_acquire_ctx {
	struct task_struct *task;
	unsigned long stamp;
	unsigned int acquired;
	unsigned short wounded;
	unsigned short is_wait_die;
#ifdef DEBUG_WW_MUTEXES
	unsigned int done_acquire;
	struct ww_class *ww_class;
	void *contending_lock;
#endif
#ifdef CONFIG_DEBUG_LOCK_ALLOC
	struct lockdep_map dep_map;
#endif
#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
	unsigned int deadlock_inject_interval;
	unsigned int deadlock_inject_countdown;
#endif
};

#define __WW_CLASS_INITIALIZER(ww_class, _is_wait_die)	    \
		{ .stamp = ATOMIC_LONG_INIT(0) \
		, .acquire_name = #ww_class "_acquire" \
		, .mutex_name = #ww_class "_mutex" \
		, .is_wait_die = _is_wait_die }

#define DEFINE_WD_CLASS(classname) \
	struct ww_class classname = __WW_CLASS_INITIALIZER(classname, 1)

#define DEFINE_WW_CLASS(classname) \
	struct ww_class classname = __WW_CLASS_INITIALIZER(classname, 0)

/**
 * ww_mutex_init - initialize the w/w mutex
 * @lock: the mutex to be initialized
 * @ww_class: the w/w class the mutex should belong to
 *
 * Initialize the w/w mutex to unlocked state and associate it with the given
 * class. Static define macro for w/w mutex is not provided and this function
 * is the only way to properly initialize the w/w mutex.
 *
 * It is not allowed to initialize an already locked mutex.
 */
static inline void ww_mutex_init(struct ww_mutex *lock,
				 struct ww_class *ww_class)
{
	ww_mutex_base_init(&lock->base, ww_class->mutex_name, &ww_class->mutex_key);
	lock->ctx = NULL;
#ifdef DEBUG_WW_MUTEXES
	lock->ww_class = ww_class;
#endif
}

/**
 * ww_acquire_init - initialize a w/w acquire context
 * @ctx: w/w acquire context to initialize
 * @ww_class: w/w class of the context
 *
 * Initializes an context to acquire multiple mutexes of the given w/w class.
 *
 * Context-based w/w mutex acquiring can be done in any order whatsoever within
 * a given lock class. Deadlocks will be detected and handled with the
 * wait/die logic.
 *
 * Mixing of context-based w/w mutex acquiring and single w/w mutex locking can
 * result in undetected deadlocks and is so forbidden. Mixing different contexts
 * for the same w/w class when acquiring mutexes can also result in undetected
 * deadlocks, and is hence also forbidden. Both types of abuse will be caught by
 * enabling CONFIG_PROVE_LOCKING.
 *
 * Nesting of acquire contexts for _different_ w/w classes is possible, subject
 * to the usual locking rules between different lock classes.
 *
 * An acquire context must be released with ww_acquire_fini by the same task
 * before the memory is freed. It is recommended to allocate the context itself
 * on the stack.
 */
static inline void ww_acquire_init(struct