/* 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 * Copyright (C) 2006, Timesys Corp., Thomas Gleixner * * This file contains the private data structure and API definitions. */ #ifndef __KERNEL_RTMUTEX_COMMON_H #define __KERNEL_RTMUTEX_COMMON_H #include #include #include /* * 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 * @lock: Pointer to the rt_mutex on which the waiter blocks * @wake_state: Wakeup state to use (TASK_NORMAL or TASK_RTLOCK_WAIT) * @prio: Priority of the waiter * @deadline: Deadline of the waiter if applicable * @ww_ctx: WW context pointer */ struct rt_mutex_waiter { struct rb_node tree_entry; struct rb_node pi_tree_entry; struct task_struct *task; struct rt_mutex_base *lock; unsigned int wake_state; int prio; u64 deadline; struct ww_acquire_ctx *ww_ctx; }; /** * rt_wake_q_head - Wrapper around regular wake_q_head to support * "sleeping" spinlocks on RT * @head: The regular wake_q_head for sleeping lock variants * @rtlock_task: Task pointer for RT lock (spin/rwlock) wakeups */ struct rt_wake_q_head { struct wake_q_head head; struct task_struct *rtlock_task; }; #define DEFINE_RT_WAKE_Q(name) \ struct rt_wake_q_head name = { \ .head = WAKE_Q_HEAD_INITIALIZER(name.head), \ .rtlock_task = NULL, \ } /* * PI-futex support (proxy locking functions, etc.): */ extern void rt_mutex_init_proxy_locked(struct rt_mutex_base *lock, struct task_struct *proxy_owner); extern void rt_mutex_proxy_unlock(struct rt_mutex_base *lock); extern int __rt_mutex_start_proxy_lock(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter, struct task_struct *task); extern int rt_mutex_start_proxy_lock(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter, struct task_struct *task); extern int rt_mutex_wait_proxy_lock(struct rt_mutex_base *lock, struct hrtimer_sleeper *to, struct rt_mutex_waiter *waiter); extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter); extern int rt_mutex_futex_trylock(struct rt_mutex_base *l); extern int __rt_mutex_futex_trylock(struct rt_mutex_base *l); extern void rt_mutex_futex_unlock(struct rt_mutex_base *lock); extern bool __rt_mutex_futex_unlock(struct rt_mutex_base *lock, struct rt_wake_q_head *wqh); extern void rt_mutex_postunlock(struct rt_wake_q_head *wqh); /* * Must be guarded because this header is included from rcu/tree_plugin.h * unconditionally. */ #ifdef CONFIG_RT_MUTEXES static inline int rt_mutex_has_waiters(struct rt_mutex_base *lock) { return !RB_EMPTY_ROOT(&lock->waiters.rb_root); } /* * Lockless speculative check whether @waiter is still the top waiter on * @lock. This is solely comparing pointers and not derefencing the * leftmost entry which might be about to vanish. */ static inline bool rt_mutex_waiter_is_top_waiter(struct rt_mutex_base *lock, struct rt_mutex_waiter *waiter) { struct rb_node *leftmost = rb_first_cached(&lock->waiters); return rb_entry(leftmost, struct rt_mutex_waiter, tree_entry) == waiter; } static inline struct rt_mutex_waiter *rt_mutex_top_waiter(struct rt_mutex_base *lock) { struct rb_node *leftmost = rb_first_cached(&lock->waiters); struct rt_mutex_waiter *w = NULL; if (leftmost) { w = rb_entry(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); } #define RT_MUTEX_HAS_WAITERS 1UL static inline struct task_struct *rt_mutex_owner(struct rt_mutex_base *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, }; static inline void __rt_mutex_base_init(struct rt_mutex_base *lock) { raw_spin_lock_init(&lock->wait_lock); lock->waiters = RB_ROOT_CACHED; lock->owner = NULL; } /* Debug functions */ static inline void debug_rt_mutex_unlock(struct rt_mutex_base *lock) { if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES)) DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current); } static inline void debug_rt_mutex_proxy_unlock(struct rt_mutex_base *lock) { if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES)) DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock)); } static inline void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter) { if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES)) memset(waiter, 0x11, sizeof(*waiter)); } static inline void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter) { if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES)) memset(waiter, 0x22, sizeof(*waiter)); } static inline void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter) { debug_rt_mutex_init_waiter(waiter); RB_CLEAR_NODE(&waiter->pi_tree_entry); RB_CLEAR_NODE(&waiter->tree_entry); waiter->wake_state = TASK_NORMAL; waiter->task = NULL; } static inline void rt_mutex_init_rtlock_waiter(struct rt_mutex_waiter *waiter) { rt_mutex_init_waiter(waiter); waiter->wake_state = TASK_RTLOCK_WAIT; } #else /* CONFIG_RT_MUTEXES */ /* Used in rcu/tree_plugin.h */ static inline struct task_struct *rt_mutex_owner(struct rt_mutex_base *lock) { return NULL; } #endif /* !CONFIG_RT_MUTEXES */ #endif