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213 lines
6.2 KiB
213 lines
6.2 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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/* |
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* RT Mutexes: blocking mutual exclusion locks with PI support |
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* |
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* started by Ingo Molnar and Thomas Gleixner: |
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* |
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* Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <[email protected]> |
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* Copyright (C) 2006, Timesys Corp., Thomas Gleixner <[email protected]> |
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* |
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* This file contains the private data structure and API definitions. |
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*/ |
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#ifndef __KERNEL_RTMUTEX_COMMON_H |
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#define __KERNEL_RTMUTEX_COMMON_H |
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#include <linux/debug_locks.h> |
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#include <linux/rtmutex.h> |
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#include <linux/sched/wake_q.h> |
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/* |
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* This is the control structure for tasks blocked on a rt_mutex, |
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* which is allocated on the kernel stack on of the blocked task. |
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* |
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* @tree_entry: pi node to enqueue into the mutex waiters tree |
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* @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree |
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* @task: task reference to the blocked task |
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* @lock: Pointer to the rt_mutex on which the waiter blocks |
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* @wake_state: Wakeup state to use (TASK_NORMAL or TASK_RTLOCK_WAIT) |
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* @prio: Priority of the waiter |
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* @deadline: Deadline of the waiter if applicable |
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* @ww_ctx: WW context pointer |
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*/ |
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struct rt_mutex_waiter { |
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struct rb_node tree_entry; |
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struct rb_node pi_tree_entry; |
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struct task_struct *task; |
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struct rt_mutex_base *lock; |
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unsigned int wake_state; |
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int prio; |
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u64 deadline; |
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struct ww_acquire_ctx *ww_ctx; |
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}; |
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/** |
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* rt_wake_q_head - Wrapper around regular wake_q_head to support |
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* "sleeping" spinlocks on RT |
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* @head: The regular wake_q_head for sleeping lock variants |
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* @rtlock_task: Task pointer for RT lock (spin/rwlock) wakeups |
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*/ |
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struct rt_wake_q_head { |
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struct wake_q_head head; |
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struct task_struct *rtlock_task; |
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}; |
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#define DEFINE_RT_WAKE_Q(name) \ |
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struct rt_wake_q_head name = { \ |
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.head = WAKE_Q_HEAD_INITIALIZER(name.head), \ |
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.rtlock_task = NULL, \ |
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} |
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/* |
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* PI-futex support (proxy locking functions, etc.): |
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*/ |
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extern void rt_mutex_init_proxy_locked(struct rt_mutex_base *lock, |
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struct task_struct *proxy_owner); |
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extern void rt_mutex_proxy_unlock(struct rt_mutex_base *lock); |
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extern int __rt_mutex_start_proxy_lock(struct rt_mutex_base *lock, |
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struct rt_mutex_waiter *waiter, |
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struct task_struct *task); |
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extern int rt_mutex_start_proxy_lock(struct rt_mutex_base *lock, |
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struct rt_mutex_waiter *waiter, |
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struct task_struct *task); |
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extern int rt_mutex_wait_proxy_lock(struct rt_mutex_base *lock, |
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struct hrtimer_sleeper *to, |
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struct rt_mutex_waiter *waiter); |
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extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex_base *lock, |
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struct rt_mutex_waiter *waiter); |
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extern int rt_mutex_futex_trylock(struct rt_mutex_base *l); |
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extern int __rt_mutex_futex_trylock(struct rt_mutex_base *l); |
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extern void rt_mutex_futex_unlock(struct rt_mutex_base *lock); |
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extern bool __rt_mutex_futex_unlock(struct rt_mutex_base *lock, |
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struct rt_wake_q_head *wqh); |
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extern void rt_mutex_postunlock(struct rt_wake_q_head *wqh); |
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/* |
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* Must be guarded because this header is included from rcu/tree_plugin.h |
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* unconditionally. |
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*/ |
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#ifdef CONFIG_RT_MUTEXES |
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static inline int rt_mutex_has_waiters(struct rt_mutex_base *lock) |
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{ |
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return !RB_EMPTY_ROOT(&lock->waiters.rb_root); |
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} |
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/* |
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* Lockless speculative check whether @waiter is still the top waiter on |
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* @lock. This is solely comparing pointers and not derefencing the |
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* leftmost entry which might be about to vanish. |
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*/ |
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static inline bool rt_mutex_waiter_is_top_waiter(struct rt_mutex_base *lock, |
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struct rt_mutex_waiter *waiter) |
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{ |
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struct rb_node *leftmost = rb_first_cached(&lock->waiters); |
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return rb_entry(leftmost, struct rt_mutex_waiter, tree_entry) == waiter; |
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} |
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static inline struct rt_mutex_waiter *rt_mutex_top_waiter(struct rt_mutex_base *lock) |
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{ |
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struct rb_node *leftmost = rb_first_cached(&lock->waiters); |
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struct rt_mutex_waiter *w = NULL; |
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if (leftmost) { |
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w = rb_entry(leftmost, struct rt_mutex_waiter, tree_entry); |
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BUG_ON(w->lock != lock); |
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} |
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return w; |
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} |
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static inline int task_has_pi_waiters(struct task_struct *p) |
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{ |
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return !RB_EMPTY_ROOT(&p->pi_waiters.rb_root); |
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} |
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static inline struct rt_mutex_waiter *task_top_pi_waiter(struct task_struct *p) |
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{ |
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return rb_entry(p->pi_waiters.rb_leftmost, struct rt_mutex_waiter, |
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pi_tree_entry); |
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} |
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#define RT_MUTEX_HAS_WAITERS 1UL |
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static inline struct task_struct *rt_mutex_owner(struct rt_mutex_base *lock) |
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{ |
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unsigned long owner = (unsigned long) READ_ONCE(lock->owner); |
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return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS); |
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} |
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/* |
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* Constants for rt mutex functions which have a selectable deadlock |
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* detection. |
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* |
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* RT_MUTEX_MIN_CHAINWALK: Stops the lock chain walk when there are |
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* no further PI adjustments to be made. |
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* |
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* RT_MUTEX_FULL_CHAINWALK: Invoke deadlock detection with a full |
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* walk of the lock chain. |
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*/ |
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enum rtmutex_chainwalk { |
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RT_MUTEX_MIN_CHAINWALK, |
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RT_MUTEX_FULL_CHAINWALK, |
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}; |
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static inline void __rt_mutex_base_init(struct rt_mutex_base *lock) |
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{ |
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raw_spin_lock_init(&lock->wait_lock); |
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lock->waiters = RB_ROOT_CACHED; |
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lock->owner = NULL; |
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} |
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/* Debug functions */ |
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static inline void debug_rt_mutex_unlock(struct rt_mutex_base *lock) |
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{ |
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if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES)) |
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DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current); |
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} |
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static inline void debug_rt_mutex_proxy_unlock(struct rt_mutex_base *lock) |
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{ |
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if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES)) |
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DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock)); |
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} |
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static inline void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter) |
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{ |
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if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES)) |
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memset(waiter, 0x11, sizeof(*waiter)); |
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} |
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static inline void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter) |
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{ |
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if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES)) |
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memset(waiter, 0x22, sizeof(*waiter)); |
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} |
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static inline void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter) |
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{ |
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debug_rt_mutex_init_waiter(waiter); |
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RB_CLEAR_NODE(&waiter->pi_tree_entry); |
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RB_CLEAR_NODE(&waiter->tree_entry); |
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waiter->wake_state = TASK_NORMAL; |
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waiter->task = NULL; |
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} |
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static inline void rt_mutex_init_rtlock_waiter(struct rt_mutex_waiter *waiter) |
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{ |
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rt_mutex_init_waiter(waiter); |
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waiter->wake_state = TASK_RTLOCK_WAIT; |
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} |
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#else /* CONFIG_RT_MUTEXES */ |
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/* Used in rcu/tree_plugin.h */ |
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static inline struct task_struct *rt_mutex_owner(struct rt_mutex_base *lock) |
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{ |
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return NULL; |
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} |
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#endif /* !CONFIG_RT_MUTEXES */ |
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#endif
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