235 строки
6.7 KiB
C
235 строки
6.7 KiB
C
/* 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 <mingo@redhat.com>
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* Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
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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 a helper for the struct rt_mutex_waiter below. A waiter goes in two
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* separate trees and they need their own copy of the sort keys because of
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* different locking requirements.
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*
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* @entry: rbtree node to enqueue into the waiters tree
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* @prio: Priority of the waiter
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* @deadline: Deadline of the waiter if applicable
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*
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* See rt_waiter_node_less() and waiter_*_prio().
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*/
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struct rt_waiter_node {
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struct rb_node entry;
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int prio;
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u64 deadline;
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};
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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: node to enqueue into the mutex waiters tree
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* @pi_tree: 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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* @ww_ctx: WW context pointer
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*
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* @tree is ordered by @lock->wait_lock
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* @pi_tree is ordered by rt_mutex_owner(@lock)->pi_lock
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*/
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struct rt_mutex_waiter {
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struct rt_waiter_node tree;
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struct rt_waiter_node pi_tree;
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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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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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lockdep_assert_held(&lock->wait_lock);
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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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lockdep_assert_held(&p->pi_lock);
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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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