1 /* SPDX-License-Identifier: GPL-2.0 */ 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> 17 #include <linux/sched/wake_q.h> 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 * 23 * @tree_entry: pi node to enqueue into the mutex waiters tree 24 * @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree 25 * @task: task reference to the blocked task 26 */ 27 struct rt_mutex_waiter { 28 struct rb_node tree_entry; 29 struct rb_node pi_tree_entry; 30 struct task_struct *task; 31 struct rt_mutex *lock; 32 #ifdef CONFIG_DEBUG_RT_MUTEXES 33 unsigned long ip; 34 struct pid *deadlock_task_pid; 35 struct rt_mutex *deadlock_lock; 36 #endif 37 int prio; 38 u64 deadline; 39 }; 40 41 /* 42 * Various helpers to access the waiters-tree: 43 */ 44 45 #ifdef CONFIG_RT_MUTEXES 46 47 static inline int rt_mutex_has_waiters(struct rt_mutex *lock) 48 { 49 return !RB_EMPTY_ROOT(&lock->waiters.rb_root); 50 } 51 52 static inline struct rt_mutex_waiter * 53 rt_mutex_top_waiter(struct rt_mutex *lock) 54 { 55 struct rb_node *leftmost = rb_first_cached(&lock->waiters); 56 struct rt_mutex_waiter *w = NULL; 57 58 if (leftmost) { 59 w = rb_entry(leftmost, struct rt_mutex_waiter, tree_entry); 60 BUG_ON(w->lock != lock); 61 } 62 return w; 63 } 64 65 static inline int task_has_pi_waiters(struct task_struct *p) 66 { 67 return !RB_EMPTY_ROOT(&p->pi_waiters.rb_root); 68 } 69 70 static inline struct rt_mutex_waiter * 71 task_top_pi_waiter(struct task_struct *p) 72 { 73 return rb_entry(p->pi_waiters.rb_leftmost, 74 struct rt_mutex_waiter, pi_tree_entry); 75 } 76 77 #else 78 79 static inline int rt_mutex_has_waiters(struct rt_mutex *lock) 80 { 81 return false; 82 } 83 84 static inline struct rt_mutex_waiter * 85 rt_mutex_top_waiter(struct rt_mutex *lock) 86 { 87 return NULL; 88 } 89 90 static inline int task_has_pi_waiters(struct task_struct *p) 91 { 92 return false; 93 } 94 95 static inline struct rt_mutex_waiter * 96 task_top_pi_waiter(struct task_struct *p) 97 { 98 return NULL; 99 } 100 101 #endif 102 103 /* 104 * lock->owner state tracking: 105 */ 106 #define RT_MUTEX_HAS_WAITERS 1UL 107 108 static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock) 109 { 110 unsigned long owner = (unsigned long) READ_ONCE(lock->owner); 111 112 return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS); 113 } 114 115 /* 116 * Constants for rt mutex functions which have a selectable deadlock 117 * detection. 118 * 119 * RT_MUTEX_MIN_CHAINWALK: Stops the lock chain walk when there are 120 * no further PI adjustments to be made. 121 * 122 * RT_MUTEX_FULL_CHAINWALK: Invoke deadlock detection with a full 123 * walk of the lock chain. 124 */ 125 enum rtmutex_chainwalk { 126 RT_MUTEX_MIN_CHAINWALK, 127 RT_MUTEX_FULL_CHAINWALK, 128 }; 129 130 /* 131 * PI-futex support (proxy locking functions, etc.): 132 */ 133 extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock); 134 extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock, 135 struct task_struct *proxy_owner); 136 extern void rt_mutex_proxy_unlock(struct rt_mutex *lock, 137 struct task_struct *proxy_owner); 138 extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter); 139 extern int __rt_mutex_start_proxy_lock(struct rt_mutex *lock, 140 struct rt_mutex_waiter *waiter, 141 struct task_struct *task); 142 extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock, 143 struct rt_mutex_waiter *waiter, 144 struct task_struct *task); 145 extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock, 146 struct hrtimer_sleeper *to, 147 struct rt_mutex_waiter *waiter); 148 extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock, 149 struct rt_mutex_waiter *waiter); 150 151 extern int rt_mutex_futex_trylock(struct rt_mutex *l); 152 extern int __rt_mutex_futex_trylock(struct rt_mutex *l); 153 154 extern void rt_mutex_futex_unlock(struct rt_mutex *lock); 155 extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock, 156 struct wake_q_head *wqh); 157 158 extern void rt_mutex_postunlock(struct wake_q_head *wake_q); 159 160 #ifdef CONFIG_DEBUG_RT_MUTEXES 161 # include "rtmutex-debug.h" 162 #else 163 # include "rtmutex.h" 164 #endif 165 166 #endif 167