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> <<
17 #include <linux/rtmutex.h> 16 #include <linux/rtmutex.h>
18 #include <linux/sched/wake_q.h> 17 #include <linux/sched/wake_q.h>
19 18
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 /* 19 /*
39 * This is the control structure for tasks blo 20 * This is the control structure for tasks blocked on a rt_mutex,
40 * which is allocated on the kernel stack on o 21 * which is allocated on the kernel stack on of the blocked task.
41 * 22 *
42 * @tree: node to enqueue into t !! 23 * @tree_entry: pi node to enqueue into the mutex waiters tree
43 * @pi_tree: node to enqueue into t !! 24 * @pi_tree_entry: pi node to enqueue into the mutex owner waiters tree
44 * @task: task reference to the 25 * @task: task reference to the blocked task
45 * @lock: Pointer to the rt_mute <<
46 * @wake_state: Wakeup state to use (T <<
47 * @ww_ctx: WW context pointer <<
48 * <<
49 * @tree is ordered by @lock->wait_lock <<
50 * @pi_tree is ordered by rt_mutex_owner(@lock <<
51 */ 26 */
52 struct rt_mutex_waiter { 27 struct rt_mutex_waiter {
53 struct rt_waiter_node tree; !! 28 struct rb_node tree_entry;
54 struct rt_waiter_node pi_tree; !! 29 struct rb_node pi_tree_entry;
55 struct task_struct *task; 30 struct task_struct *task;
56 struct rt_mutex_base *lock; !! 31 struct rt_mutex *lock;
57 unsigned int wake_state; !! 32 #ifdef CONFIG_DEBUG_RT_MUTEXES
58 struct ww_acquire_ctx *ww_ctx; !! 33 unsigned long ip;
59 }; !! 34 struct pid *deadlock_task_pid;
60 !! 35 struct rt_mutex *deadlock_lock;
61 /** !! 36 #endif
62 * rt_wake_q_head - Wrapper around regular wak !! 37 int prio;
63 * "sleeping" spinlocks on RT !! 38 u64 deadline;
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 }; 39 };
71 40
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 /* 41 /*
79 * PI-futex support (proxy locking functions, !! 42 * Various helpers to access the waiters-tree:
80 */ 43 */
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 44
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 /* <<
106 * Must be guarded because this header is incl <<
107 * unconditionally. <<
108 */ <<
109 #ifdef CONFIG_RT_MUTEXES 45 #ifdef CONFIG_RT_MUTEXES
110 static inline int rt_mutex_has_waiters(struct <<
111 { <<
112 return !RB_EMPTY_ROOT(&lock->waiters.r <<
113 } <<
114 46
115 /* !! 47 static inline int rt_mutex_has_waiters(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 { 48 {
123 struct rb_node *leftmost = rb_first_ca !! 49 return !RB_EMPTY_ROOT(&lock->waiters.rb_root);
124 <<
125 return rb_entry(leftmost, struct rt_mu <<
126 } 50 }
127 51
128 static inline struct rt_mutex_waiter *rt_mutex !! 52 static inline struct rt_mutex_waiter *
>> 53 rt_mutex_top_waiter(struct rt_mutex *lock)
129 { 54 {
130 struct rb_node *leftmost = rb_first_ca 55 struct rb_node *leftmost = rb_first_cached(&lock->waiters);
131 struct rt_mutex_waiter *w = NULL; 56 struct rt_mutex_waiter *w = NULL;
132 57
133 lockdep_assert_held(&lock->wait_lock); <<
134 <<
135 if (leftmost) { 58 if (leftmost) {
136 w = rb_entry(leftmost, struct !! 59 w = rb_entry(leftmost, struct rt_mutex_waiter, tree_entry);
137 BUG_ON(w->lock != lock); 60 BUG_ON(w->lock != lock);
138 } 61 }
139 return w; 62 return w;
140 } 63 }
141 64
142 static inline int task_has_pi_waiters(struct t 65 static inline int task_has_pi_waiters(struct task_struct *p)
143 { 66 {
144 return !RB_EMPTY_ROOT(&p->pi_waiters.r 67 return !RB_EMPTY_ROOT(&p->pi_waiters.rb_root);
145 } 68 }
146 69
147 static inline struct rt_mutex_waiter *task_top !! 70 static inline struct rt_mutex_waiter *
>> 71 task_top_pi_waiter(struct task_struct *p)
148 { 72 {
149 lockdep_assert_held(&p->pi_lock); !! 73 return rb_entry(p->pi_waiters.rb_leftmost,
>> 74 struct rt_mutex_waiter, pi_tree_entry);
>> 75 }
>> 76
>> 77 #else
150 78
151 return rb_entry(p->pi_waiters.rb_leftm !! 79 static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
152 pi_tree.entry); !! 80 {
>> 81 return false;
153 } 82 }
154 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 */
155 #define RT_MUTEX_HAS_WAITERS 1UL 106 #define RT_MUTEX_HAS_WAITERS 1UL
156 107
157 static inline struct task_struct *rt_mutex_own !! 108 static inline struct task_struct *rt_mutex_owner(struct rt_mutex *lock)
158 { 109 {
159 unsigned long owner = (unsigned long) 110 unsigned long owner = (unsigned long) READ_ONCE(lock->owner);
160 111
161 return (struct task_struct *) (owner & 112 return (struct task_struct *) (owner & ~RT_MUTEX_HAS_WAITERS);
162 } 113 }
163 114
164 /* 115 /*
165 * Constants for rt mutex functions which have 116 * Constants for rt mutex functions which have a selectable deadlock
166 * detection. 117 * detection.
167 * 118 *
168 * RT_MUTEX_MIN_CHAINWALK: Stops the lock 119 * RT_MUTEX_MIN_CHAINWALK: Stops the lock chain walk when there are
169 * no further PI 120 * no further PI adjustments to be made.
170 * 121 *
171 * RT_MUTEX_FULL_CHAINWALK: Invoke deadloc 122 * RT_MUTEX_FULL_CHAINWALK: Invoke deadlock detection with a full
172 * walk of the lo 123 * walk of the lock chain.
173 */ 124 */
174 enum rtmutex_chainwalk { 125 enum rtmutex_chainwalk {
175 RT_MUTEX_MIN_CHAINWALK, 126 RT_MUTEX_MIN_CHAINWALK,
176 RT_MUTEX_FULL_CHAINWALK, 127 RT_MUTEX_FULL_CHAINWALK,
177 }; 128 };
178 129
179 static inline void __rt_mutex_base_init(struct !! 130 /*
180 { !! 131 * PI-futex support (proxy locking functions, etc.):
181 raw_spin_lock_init(&lock->wait_lock); !! 132 */
182 lock->waiters = RB_ROOT_CACHED; !! 133 extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
183 lock->owner = NULL; !! 134 extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
184 } !! 135 struct task_struct *proxy_owner);
185 !! 136 extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
186 /* Debug functions */ !! 137 struct task_struct *proxy_owner);
187 static inline void debug_rt_mutex_unlock(struc !! 138 extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
188 { !! 139 extern int __rt_mutex_start_proxy_lock(struct rt_mutex *lock,
189 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES !! 140 struct rt_mutex_waiter *waiter,
190 DEBUG_LOCKS_WARN_ON(rt_mutex_o !! 141 struct task_struct *task);
191 } !! 142 extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
192 !! 143 struct rt_mutex_waiter *waiter,
193 static inline void debug_rt_mutex_proxy_unlock !! 144 struct task_struct *task);
194 { !! 145 extern int rt_mutex_wait_proxy_lock(struct rt_mutex *lock,
195 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES !! 146 struct hrtimer_sleeper *to,
196 DEBUG_LOCKS_WARN_ON(!rt_mutex_ !! 147 struct rt_mutex_waiter *waiter);
197 } !! 148 extern bool rt_mutex_cleanup_proxy_lock(struct rt_mutex *lock,
198 !! 149 struct rt_mutex_waiter *waiter);
199 static inline void debug_rt_mutex_init_waiter( <<
200 { <<
201 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES <<
202 memset(waiter, 0x11, sizeof(*w <<
203 } <<
204 <<
205 static inline void debug_rt_mutex_free_waiter( <<
206 { <<
207 if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES <<
208 memset(waiter, 0x22, sizeof(*w <<
209 } <<
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 } <<
219 150
220 static inline void rt_mutex_init_rtlock_waiter !! 151 extern int rt_mutex_futex_trylock(struct rt_mutex *l);
221 { !! 152 extern int __rt_mutex_futex_trylock(struct rt_mutex *l);
222 rt_mutex_init_waiter(waiter); <<
223 waiter->wake_state = TASK_RTLOCK_WAIT; <<
224 } <<
225 153
226 #else /* CONFIG_RT_MUTEXES */ !! 154 extern void rt_mutex_futex_unlock(struct rt_mutex *lock);
227 /* Used in rcu/tree_plugin.h */ !! 155 extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock,
228 static inline struct task_struct *rt_mutex_own !! 156 struct wake_q_head *wqh);
229 { !! 157
230 return NULL; !! 158 extern void rt_mutex_postunlock(struct wake_q_head *wake_q);
231 } !! 159
232 #endif /* !CONFIG_RT_MUTEXES */ !! 160 #ifdef CONFIG_DEBUG_RT_MUTEXES
>> 161 # include "rtmutex-debug.h"
>> 162 #else
>> 163 # include "rtmutex.h"
>> 164 #endif
233 165
234 #endif 166 #endif
235 167
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