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