[mirror_ubuntu-bionic-kernel.git] / kernel / locking / rtmutex_common.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * RT Mutexes: blocking mutual exclusion locks with PI support
 *
 * started by Ingo Molnar and Thomas Gleixner:
 *
 *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 *  Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
 *
 * This file contains the private data structure and API definitions.
 */

#ifndef __KERNEL_RTMUTEX_COMMON_H
#define __KERNEL_RTMUTEX_COMMON_H

#include <linux/rtmutex.h>
#include <linux/sched/wake_q.h>

/*
 * This is the control structure for tasks blocked on a rt_mutex,
 * which is allocated on the kernel stack on of the blocked task.
 *
 * @tree_entry:		pi node to enqueue into the mutex waiters tree
 * @pi_tree_entry:	pi node to enqueue into the mutex owner waiters tree
 * @task:		task reference to the blocked task
 */
struct rt_mutex_waiter {
	struct rb_node          tree_entry;
	struct rb_node          pi_tree_entry;
	struct task_struct	*task;
	struct rt_mutex		*lock;
#ifdef CONFIG_DEBUG_RT_MUTEXES
	unsigned long		ip;
	struct pid		*deadlock_task_pid;
	struct rt_mutex		*deadlock_lock;
#endif
	int prio;
	u64 deadline;
};

/*
 * Various helpers to access the waiters-tree:
 */

#ifdef CONFIG_RT_MUTEXES

static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
{
	return !RB_EMPTY_ROOT(&lock->waiters.rb_root);
}

static inline struct rt_mutex_waiter *
rt_mutex_top_waiter(struct rt_mutex *lock)
{
	struct rt_mutex_waiter *w;

	w = rb_entry(lock->waiters.rb_leftmost,
		     struct rt_mutex_waiter, tree_entry);
	BUG_ON(w->lock != lock);

	return w;
}

static inline int task_has_pi_waiters(struct task_struct *p)
{
	return !RB_EMPTY_ROOT(&p->pi_waiters.rb_root);
}

static inline struct rt_mutex_waiter *
task_top_pi_waiter(struct task_struct *p)
{
	return rb_entry(p->pi_waiters.rb_leftmost,
			struct rt_mutex_waiter, pi_tree_entry);
}

#else

static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
{
	return false;
}

static inline struct rt_mutex_waiter *
rt_mutex_top_waiter(struct rt_mutex *lock)
{
	return NULL;
}

static inline int task_has_pi_waiters(struct task_struct *p)
{
	return false;
}

static inline struct rt_mutex_waiter *
task_top_pi_waiter(struct task_struct *p)
{
	return NULL;
}

#endif

/*
 * lock->owner state tracking:
 */
#define RT_MUTEX_HAS_WAITERS	1UL

static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
{
	unsigned long owner = (unsigned long) READ_ONCE(lock->owner);

	return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
}

/*
 * Constants for rt mutex functions which have a selectable deadlock
 * detection.
 *
 * RT_MUTEX_MIN_CHAINWALK:	Stops the lock chain walk when there are
 *				no further PI adjustments to be made.
 *
 * RT_MUTEX_FULL_CHAINWALK:	Invoke deadlock detection with a full
 *				walk of the lock chain.
 */
enum rtmutex_chainwalk {
	RT_MUTEX_MIN_CHAINWALK,
	RT_MUTEX_FULL_CHAINWALK,
};

/*
 * PI-futex support (proxy locking functions, etc.):
 */
extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
				       struct task_struct *proxy_owner);
extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
				  struct task_struct *proxy_owner);
extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
extern int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
				     struct rt_mutex_waiter *waiter,
				     struct task_struct *task);
extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
				     struct rt_mutex_waiter *waiter,
				     struct task_struct *task);
extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
			       struct hrtimer_sleeper *to,
			       struct rt_mutex_waiter *waiter);
extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
				 struct rt_mutex_waiter *waiter);

extern int rt_mutex_futex_trylock(struct rt_mutex *l);
extern int __rt_mutex_futex_trylock(struct rt_mutex *l);

extern void rt_mutex_futex_unlock(struct rt_mutex *lock);
extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
				 struct wake_q_head *wqh);

extern void rt_mutex_postunlock(struct wake_q_head *wake_q);

#ifdef CONFIG_DEBUG_RT_MUTEXES
# include "rtmutex-debug.h"
#else
# include "rtmutex.h"
#endif

#endif
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
23f78d4a IM	2	/*
	3	* RT Mutexes: blocking mutual exclusion locks with PI support
	4	*
	5	* started by Ingo Molnar and Thomas Gleixner:
	6	*
	7	* Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
	8	* Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
	9	*
	10	* This file contains the private data structure and API definitions.
	11	*/
	12
	13	#ifndef __KERNEL_RTMUTEX_COMMON_H
	14	#define __KERNEL_RTMUTEX_COMMON_H
	15
	16	#include <linux/rtmutex.h>
84f001e1	17	#include <linux/sched/wake_q.h>
23f78d4a IM	18
	19	/*
	20	* This is the control structure for tasks blocked on a rt_mutex,
	21	* which is allocated on the kernel stack on of the blocked task.
	22	*
fb00aca4 PZ	23	* @tree_entry: pi node to enqueue into the mutex waiters tree
fb00aca4 PZ	24	* @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree
23f78d4a IM	25	* @task: task reference to the blocked task
	26	*/
	27	struct rt_mutex_waiter {
fb00aca4 PZ	28	struct rb_node tree_entry;
fb00aca4 PZ	29	struct rb_node pi_tree_entry;
23f78d4a IM	30	struct task_struct *task;
	31	struct rt_mutex *lock;
	32	#ifdef CONFIG_DEBUG_RT_MUTEXES
	33	unsigned long ip;
48d13e48	34	struct pid *deadlock_task_pid;
23f78d4a IM	35	struct rt_mutex *deadlock_lock;
23f78d4a IM	36	#endif
2d3d891d	37	int prio;
e0aad5b4	38	u64 deadline;
23f78d4a IM	39	};
	40
	41	/*
fb00aca4	42	* Various helpers to access the waiters-tree:
23f78d4a	43	*/
bc2eecd7 NP	44
	45	#ifdef CONFIG_RT_MUTEXES
	46
23f78d4a IM	47	static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
23f78d4a IM	48	{
a23ba907	49	return !RB_EMPTY_ROOT(&lock->waiters.rb_root);
23f78d4a IM	50	}
	51
	52	static inline struct rt_mutex_waiter *
	53	rt_mutex_top_waiter(struct rt_mutex *lock)
	54	{
	55	struct rt_mutex_waiter *w;
	56
a23ba907 DB	57	w = rb_entry(lock->waiters.rb_leftmost,
a23ba907 DB	58	struct rt_mutex_waiter, tree_entry);
23f78d4a IM	59	BUG_ON(w->lock != lock);
	60
	61	return w;
	62	}
	63
	64	static inline int task_has_pi_waiters(struct task_struct *p)
	65	{
a23ba907	66	return !RB_EMPTY_ROOT(&p->pi_waiters.rb_root);
23f78d4a IM	67	}
	68
	69	static inline struct rt_mutex_waiter *
	70	task_top_pi_waiter(struct task_struct *p)
	71	{
a23ba907 DB	72	return rb_entry(p->pi_waiters.rb_leftmost,
a23ba907 DB	73	struct rt_mutex_waiter, pi_tree_entry);
23f78d4a IM	74	}
23f78d4a IM	75
bc2eecd7 NP	76	#else
	77
	78	static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
	79	{
	80	return false;
	81	}
	82
	83	static inline struct rt_mutex_waiter *
	84	rt_mutex_top_waiter(struct rt_mutex *lock)
	85	{
	86	return NULL;
	87	}
	88
	89	static inline int task_has_pi_waiters(struct task_struct *p)
	90	{
	91	return false;
	92	}
	93
	94	static inline struct rt_mutex_waiter *
	95	task_top_pi_waiter(struct task_struct *p)
	96	{
	97	return NULL;
	98	}
	99
	100	#endif
	101
23f78d4a IM	102	/*
	103	* lock->owner state tracking:
	104	*/
8161239a	105	#define RT_MUTEX_HAS_WAITERS 1UL
23f78d4a IM	106
	107	static inline struct task_struct rt_mutex_owner(struct rt_mutex lock)
	108	{
1be5d4fa TG	109	unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
1be5d4fa TG	110
b5016e82	111	return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
23f78d4a IM	112	}
23f78d4a IM	113
8930ed80 TG	114	/*
	115	* Constants for rt mutex functions which have a selectable deadlock
	116	* detection.
	117	*
	118	* RT_MUTEX_MIN_CHAINWALK: Stops the lock chain walk when there are
	119	* no further PI adjustments to be made.
	120	*
	121	* RT_MUTEX_FULL_CHAINWALK: Invoke deadlock detection with a full
	122	* walk of the lock chain.
	123	*/
	124	enum rtmutex_chainwalk {
	125	RT_MUTEX_MIN_CHAINWALK,
	126	RT_MUTEX_FULL_CHAINWALK,
	127	};
	128
c87e2837 IM	129	/*
	130	* PI-futex support (proxy locking functions, etc.):
	131	*/
	132	extern struct task_struct rt_mutex_next_owner(struct rt_mutex lock);
	133	extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
	134	struct task_struct *proxy_owner);
	135	extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
	136	struct task_struct *proxy_owner);
50809358	137	extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
56222b21 PZ	138	extern int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
	139	struct rt_mutex_waiter *waiter,
	140	struct task_struct *task);
8dac456a DH	141	extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
8dac456a DH	142	struct rt_mutex_waiter *waiter,
c051b21f	143	struct task_struct *task);
38d589f2 PZ	144	extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
	145	struct hrtimer_sleeper *to,
	146	struct rt_mutex_waiter *waiter);
	147	extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
	148	struct rt_mutex_waiter *waiter);
5293c2ef	149
5293c2ef	150	extern int rt_mutex_futex_trylock(struct rt_mutex *l);
c1e2f0ea	151	extern int __rt_mutex_futex_trylock(struct rt_mutex *l);
5293c2ef PZ	152
	153	extern void rt_mutex_futex_unlock(struct rt_mutex *lock);
	154	extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
	155	struct wake_q_head *wqh);
	156
aa2bfe55	157	extern void rt_mutex_postunlock(struct wake_q_head *wake_q);
36cf3b5c TG	158
	159	#ifdef CONFIG_DEBUG_RT_MUTEXES
	160	# include "rtmutex-debug.h"
	161	#else
	162	# include "rtmutex.h"
	163	#endif
	164
23f78d4a	165	#endif