1 /* SPDX-License-Identifier: GPL-2.0 */ 1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* 2 /*
3 * RT Mutexes: blocking mutual exclusion locks 3 * RT Mutexes: blocking mutual exclusion locks with PI support
4 * 4 *
5 * started by Ingo Molnar and Thomas Gleixner: 5 * started by Ingo Molnar and Thomas Gleixner:
6 * 6 *
7 * Copyright (C) 2004-2006 Red Hat, Inc., Ing 7 * Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
8 * Copyright (C) 2006, Timesys Corp., Thomas 8 * Copyright (C) 2006, Timesys Corp., Thomas Gleixner <tglx@timesys.com>
9 * 9 *
10 * This file contains the private data structu 10 * This file contains the private data structure and API definitions.
11 */ 11 */
12 12
13 #ifndef __KERNEL_RTMUTEX_COMMON_H 13 #ifndef __KERNEL_RTMUTEX_COMMON_H
14 #define __KERNEL_RTMUTEX_COMMON_H 14 #define __KERNEL_RTMUTEX_COMMON_H
15 15
16 #include <linux/debug_locks.h> 16 #include <linux/debug_locks.h>
17 #include <linux/rtmutex.h> 17 #include <linux/rtmutex.h>
18 #include <linux/sched/wake_q.h> 18 #include <linux/sched/wake_q.h>
19 19
20 <<
21 /* <<
22 * This is a helper for the struct rt_mutex_wa <<
23 * separate trees and they need their own copy <<
24 * different locking requirements. <<
25 * <<
26 * @entry: rbtree node to enqueue <<
27 * @prio: Priority of the waiter <<
28 * @deadline: Deadline of the waiter <<
29 * <<
30 * See rt_waiter_node_less() and waiter_*_prio <<
31 */ <<
32 struct rt_waiter_node { <<
33 struct rb_node entry; <<
34 int prio; <<
35 u64 deadline; <<
36 }; <<
37 <<
38 /* 20 /*
39 * This is the control structure for tasks blo 21 * This is the control structure for tasks blocked on a rt_mutex,
40 * which is allocated on the kernel stack on o 22 * which is allocated on the kernel stack on of the blocked task.
41 * 23 *
42 * @tree: node to enqueue into t !! 24 * @tree_entry: pi node to enqueue into the mutex waiters tree
43 * @pi_tree: node to enqueue into t !! 25 * @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree
44 * @task: task reference to the 26 * @task: task reference to the blocked task
45 * @lock: Pointer to the rt_mute 27 * @lock: Pointer to the rt_mutex on which the waiter blocks
46 * @wake_state: Wakeup state to use (T !! 28 * @prio: Priority of the waiter
47 * @ww_ctx: WW context pointer !! 29 * @deadline: Deadline of the waiter if applicable
48 * <<
49 * @tree is ordered by @lock->wait_lock <<
50 * @pi_tree is ordered by rt_mutex_owner(@lock <<
51 */ 30 */
52 struct rt_mutex_waiter { 31 struct rt_mutex_waiter {
53 struct rt_waiter_node tree; !! 32 struct rb_node tree_entry;
54 struct rt_waiter_node pi_tree; !! 33 struct rb_node pi_tree_entry;
55 struct task_struct *task; 34 struct task_struct *task;
56 struct rt_mutex_base *lock; !! 35 struct rt_mutex *lock;
57 unsigned int wake_state; !! 36 int prio;
58 struct ww_acquire_ctx *ww_ctx; !! 37 u64 deadline;
59 }; <<
60 <<
61 /** <<
62 * rt_wake_q_head - Wrapper around regular wak <<
63 * "sleeping" spinlocks on RT <<
64 * @head: The regular wake_q_hea <<
65 * @rtlock_task: Task pointer for RT lo <<
66 */ <<
67 struct rt_wake_q_head { <<
68 struct wake_q_head head; <<
69 struct task_struct *rtlock_task; <<
70 }; 38 };
71 39
72 #define DEFINE_RT_WAKE_Q(name) <<
73 struct rt_wake_q_head name = { <<
74 .head = WAKE_Q_HEAD_ <<
75 .rtlock_task = NULL, <<
76 } <<
77 <<
78 /* <<
79 * PI-futex support (proxy locking functions, <<
80 */ <<
81 extern void rt_mutex_init_proxy_locked(struct <<
82 struct <<
83 extern void rt_mutex_proxy_unlock(struct rt_mu <<
84 extern int __rt_mutex_start_proxy_lock(struct <<
85 struct rt <<
86 struct ta <<
87 extern int rt_mutex_start_proxy_lock(struct rt <<
88 struct rt <<
89 struct ta <<
90 extern int rt_mutex_wait_proxy_lock(struct rt_ <<
91 struct hrtimer_ <<
92 struct rt_mutex <<
93 extern bool rt_mutex_cleanup_proxy_lock(struct <<
94 struct rt_mut <<
95 <<
96 extern int rt_mutex_futex_trylock(struct rt_mu <<
97 extern int __rt_mutex_futex_trylock(struct rt_ <<
98 <<
99 extern void rt_mutex_futex_unlock(struct rt_mu <<
100 extern bool __rt_mutex_futex_unlock(struct rt_ <<
101 struct rt_wake <<
102 <<
103 extern void rt_mutex_postunlock(struct rt_wake <<
104 <<
105 /* 40 /*
106 * Must be guarded because this header is incl 41 * Must be guarded because this header is included from rcu/tree_plugin.h
107 * unconditionally. 42 * unconditionally.
108 */ 43 */
109 #ifdef CONFIG_RT_MUTEXES 44 #ifdef CONFIG_RT_MUTEXES
110 static inline int rt_mutex_has_waiters(struct !! 45 static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
111 { 46 {
112 return !RB_EMPTY_ROOT(&lock->waiters.r 47 return !RB_EMPTY_ROOT(&lock->waiters.rb_root);
113 } 48 }
114 49
115 /* !! 50 static inline struct rt_mutex_waiter *rt_mutex_top_waiter(struct rt_mutex *lock)
116 * Lockless speculative check whether @waiter <<
117 * @lock. This is solely comparing pointers an <<
118 * leftmost entry which might be about to vani <<
119 */ <<
120 static inline bool rt_mutex_waiter_is_top_wait <<
121 <<
122 { <<
123 struct rb_node *leftmost = rb_first_ca <<
124 <<
125 return rb_entry(leftmost, struct rt_mu <<
126 } <<
127 <<
128 static inline struct rt_mutex_waiter *rt_mutex <<
129 { 51 {
130 struct rb_node *leftmost = rb_first_ca 52 struct rb_node *leftmost = rb_first_cached(&lock->waiters);
131 struct rt_mutex_waiter *w = NULL; 53 struct rt_mutex_waiter *w = NULL;
132 54
133 lockdep_assert_held(&lock->wait_lock); <<
134 <<
135 if (leftmost) { 55 if (leftmost) {
136 w = rb_entry(leftmost, struct !! 56 w = rb_entry(leftmost, struct rt_mutex_waiter, tree_entry);
137 BUG_ON(w->lock != lock); 57 BUG_ON(w->lock != lock);
138 } 58 }
139 return w; 59 return w;
140 } 60 }
141 61
142 static inline int task_has_pi_waiters(struct t 62 static inline int task_has_pi_waiters(struct task_struct *p)
143 { 63 {
144 return !RB_EMPTY_ROOT(&p->pi_waiters.r 64 return !RB_EMPTY_ROOT(&p->pi_waiters.rb_root);
145 } 65 }
146 66
147 static inline struct rt_mutex_waiter *task_top 67 static inline struct rt_mutex_waiter *task_top_pi_waiter(struct task_struct *p)
148 { 68 {
149 lockdep_assert_held(&p->pi_lock); <<
150 <<
151 return rb_entry(p->pi_waiters.rb_leftm 69 return rb_entry(p->pi_waiters.rb_leftmost, struct rt_mutex_waiter,
152 pi_tree.entry); !! 70 pi_tree_entry);
153 } 71 }
154 72
155 #define RT_MUTEX_HAS_WAITERS 1UL 73 #define RT_MUTEX_HAS_WAITERS 1UL
156 74
157 static inline struct task_struct *rt_mutex_own !! 75 static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
158 { 76 {
159 unsigned long owner = (unsigned long) 77 unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
160 78
161 return (struct task_struct *) (owner & 79 return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
162 } 80 }
>> 81 #else /* CONFIG_RT_MUTEXES */
>> 82 /* Used in rcu/tree_plugin.h */
>> 83 static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
>> 84 {
>> 85 return NULL;
>> 86 }
>> 87 #endif /* !CONFIG_RT_MUTEXES */
163 88
164 /* 89 /*
165 * Constants for rt mutex functions which have 90 * Constants for rt mutex functions which have a selectable deadlock
166 * detection. 91 * detection.
167 * 92 *
168 * RT_MUTEX_MIN_CHAINWALK: Stops the lock 93 * RT_MUTEX_MIN_CHAINWALK: Stops the lock chain walk when there are
169 * no further PI 94 * no further PI adjustments to be made.
170 * 95 *
171 * RT_MUTEX_FULL_CHAINWALK: Invoke deadloc 96 * RT_MUTEX_FULL_CHAINWALK: Invoke deadlock detection with a full
172 * walk of the lo 97 * walk of the lock chain.
173 */ 98 */
174 enum rtmutex_chainwalk { 99 enum rtmutex_chainwalk {
175 RT_MUTEX_MIN_CHAINWALK, 100 RT_MUTEX_MIN_CHAINWALK,
176 RT_MUTEX_FULL_CHAINWALK, 101 RT_MUTEX_FULL_CHAINWALK,
177 }; 102 };
178 103
179 static inline void __rt_mutex_base_init(struct !! 104 static inline void __rt_mutex_basic_init(struct rt_mutex *lock)
180 { 105 {
>> 106 lock->owner = NULL;
181 raw_spin_lock_init(&lock->wait_lock); 107 raw_spin_lock_init(&lock->wait_lock);
182 lock->waiters = RB_ROOT_CACHED; 108 lock->waiters = RB_ROOT_CACHED;
183 lock->owner = NULL; <<
184 } 109 }
185 110
>> 111 /*
>> 112 * PI-futex support (proxy locking functions, etc.):
>> 113 */
>> 114 extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
>> 115 struct task_struct *proxy_owner);
>> 116 extern void rt_mutex_proxy_unlock(struct rt_mutex *lock);
>> 117 extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
>> 118 extern int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
>> 119 struct rt_mutex_waiter *waiter,
>> 120 struct task_struct *task);
>> 121 extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
>> 122 struct rt_mutex_waiter *waiter,
>> 123 struct task_struct *task);
>> 124 extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
>> 125 struct hrtimer_sleeper *to,
>> 126 struct rt_mutex_waiter *waiter);
>> 127 extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
>> 128 struct rt_mutex_waiter *waiter);
>> 129
>> 130 extern int rt_mutex_futex_trylock(struct rt_mutex *l);
>> 131 extern int __rt_mutex_futex_trylock(struct rt_mutex *l);
>> 132
>> 133 extern void rt_mutex_futex_unlock(struct rt_mutex *lock);
>> 134 extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
>> 135 struct wake_q_head *wqh);
>> 136
>> 137 extern void rt_mutex_postunlock(struct wake_q_head *wake_q);
>> 138
186 /* Debug functions */ 139 /* Debug functions */
187 static inline void debug_rt_mutex_unlock(struc !! 140 static inline void debug_rt_mutex_unlock(struct rt_mutex *lock)
188 { 141 {
189 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES 142 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
190 DEBUG_LOCKS_WARN_ON(rt_mutex_o 143 DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current);
191 } 144 }
192 145
193 static inline void debug_rt_mutex_proxy_unlock !! 146 static inline void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
194 { 147 {
195 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES 148 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
196 DEBUG_LOCKS_WARN_ON(!rt_mutex_ 149 DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock));
197 } 150 }
198 151
199 static inline void debug_rt_mutex_init_waiter( 152 static inline void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
200 { 153 {
201 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES 154 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
202 memset(waiter, 0x11, sizeof(*w 155 memset(waiter, 0x11, sizeof(*waiter));
203 } 156 }
204 157
205 static inline void debug_rt_mutex_free_waiter( 158 static inline void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
206 { 159 {
207 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES 160 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES))
208 memset(waiter, 0x22, sizeof(*w 161 memset(waiter, 0x22, sizeof(*waiter));
209 } 162 }
210 <<
211 static inline void rt_mutex_init_waiter(struct <<
212 { <<
213 debug_rt_mutex_init_waiter(waiter); <<
214 RB_CLEAR_NODE(&waiter->pi_tree.entry); <<
215 RB_CLEAR_NODE(&waiter->tree.entry); <<
216 waiter->wake_state = TASK_NORMAL; <<
217 waiter->task = NULL; <<
218 } <<
219 <<
220 static inline void rt_mutex_init_rtlock_waiter <<
221 { <<
222 rt_mutex_init_waiter(waiter); <<
223 waiter->wake_state = TASK_RTLOCK_WAIT; <<
224 } <<
225 <<
226 #else /* CONFIG_RT_MUTEXES */ <<
227 /* Used in rcu/tree_plugin.h */ <<
228 static inline struct task_struct *rt_mutex_own <<
229 { <<
230 return NULL; <<
231 } <<
232 #endif /* !CONFIG_RT_MUTEXES */ <<
233 163
234 #endif 164 #endif
235 165
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