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