1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
|
Subject: locking/rtmutex: Provide rt_mutex_slowlock_locked()
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue Jul 6 16:36:46 2021 +0200
From: Thomas Gleixner <tglx@linutronix.de>
Split the inner workings of rt_mutex_slowlock() out into a separate
function which can be reused by the upcoming RT lock substitutions,
e.g. for rw_semaphores.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
V2: Add the dropped debug_rt_mutex_free_waiter() - Valentin
---
kernel/locking/rtmutex.c | 100 ++++++++++++++++++++++++-------------------
kernel/locking/rtmutex_api.c | 2
2 files changed, 59 insertions(+), 43 deletions(-)
---
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1106,7 +1106,7 @@ static void __sched remove_waiter(struct
}
/**
- * __rt_mutex_slowlock() - Perform the wait-wake-try-to-take loop
+ * rt_mutex_slowlock_block() - Perform the wait-wake-try-to-take loop
* @lock: the rt_mutex to take
* @state: the state the task should block in (TASK_INTERRUPTIBLE
* or TASK_UNINTERRUPTIBLE)
@@ -1115,10 +1115,10 @@ static void __sched remove_waiter(struct
*
* Must be called with lock->wait_lock held and interrupts disabled
*/
-static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock,
- unsigned int state,
- struct hrtimer_sleeper *timeout,
- struct rt_mutex_waiter *waiter)
+static int __sched rt_mutex_slowlock_block(struct rt_mutex_base *lock,
+ unsigned int state,
+ struct hrtimer_sleeper *timeout,
+ struct rt_mutex_waiter *waiter)
{
int ret = 0;
@@ -1168,52 +1168,37 @@ static void __sched rt_mutex_handle_dead
}
}
-/*
- * Slow path lock function:
+/**
+ * __rt_mutex_slowlock - Locking slowpath invoked with lock::wait_lock held
+ * @lock: The rtmutex to block lock
+ * @state: The task state for sleeping
+ * @chwalk: Indicator whether full or partial chainwalk is requested
+ * @waiter: Initializer waiter for blocking
*/
-static int __sched rt_mutex_slowlock(struct rt_mutex_base *lock,
- unsigned int state,
- struct hrtimer_sleeper *timeout,
- enum rtmutex_chainwalk chwalk)
+static int __sched __rt_mutex_slowlock(struct rt_mutex_base *lock,
+ unsigned int state,
+ enum rtmutex_chainwalk chwalk,
+ struct rt_mutex_waiter *waiter)
{
- struct rt_mutex_waiter waiter;
- unsigned long flags;
- int ret = 0;
-
- rt_mutex_init_waiter(&waiter);
+ int ret;
- /*
- * Technically we could use raw_spin_[un]lock_irq() here, but this can
- * be called in early boot if the cmpxchg() fast path is disabled
- * (debug, no architecture support). In this case we will acquire the
- * rtmutex with lock->wait_lock held. But we cannot unconditionally
- * enable interrupts in that early boot case. So we need to use the
- * irqsave/restore variants.
- */
- raw_spin_lock_irqsave(&lock->wait_lock, flags);
+ lockdep_assert_held(&lock->wait_lock);
/* Try to acquire the lock again: */
- if (try_to_take_rt_mutex(lock, current, NULL)) {
- raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
+ if (try_to_take_rt_mutex(lock, current, NULL))
return 0;
- }
set_current_state(state);
- /* Setup the timer, when timeout != NULL */
- if (unlikely(timeout))
- hrtimer_start_expires(&timeout->timer, HRTIMER_MODE_ABS);
-
- ret = task_blocks_on_rt_mutex(lock, &waiter, current, chwalk);
+ ret = task_blocks_on_rt_mutex(lock, waiter, current, chwalk);
if (likely(!ret))
- /* sleep on the mutex */
- ret = __rt_mutex_slowlock(lock, state, timeout, &waiter);
+ ret = rt_mutex_slowlock_block(lock, state, NULL, waiter);
if (unlikely(ret)) {
__set_current_state(TASK_RUNNING);
- remove_waiter(lock, &waiter);
- rt_mutex_handle_deadlock(ret, chwalk, &waiter);
+ remove_waiter(lock, waiter);
+ rt_mutex_handle_deadlock(ret, chwalk, waiter);
}
/*
@@ -1221,14 +1206,45 @@ static int __sched rt_mutex_slowlock(str
* unconditionally. We might have to fix that up.
*/
fixup_rt_mutex_waiters(lock);
+ return ret;
+}
- raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
+static inline int __rt_mutex_slowlock_locked(struct rt_mutex_base *lock,
+ unsigned int state)
+{
+ struct rt_mutex_waiter waiter;
+ int ret;
- /* Remove pending timer: */
- if (unlikely(timeout))
- hrtimer_cancel(&timeout->timer);
+ rt_mutex_init_waiter(&waiter);
+
+ ret = __rt_mutex_slowlock(lock, state, RT_MUTEX_MIN_CHAINWALK, &waiter);
debug_rt_mutex_free_waiter(&waiter);
+ return ret;
+}
+
+/*
+ * rt_mutex_slowlock - Locking slowpath invoked when fast path fails
+ * @lock: The rtmutex to block lock
+ * @state: The task state for sleeping
+ */
+static int __sched rt_mutex_slowlock(struct rt_mutex_base *lock,
+ unsigned int state)
+{
+ unsigned long flags;
+ int ret;
+
+ /*
+ * Technically we could use raw_spin_[un]lock_irq() here, but this can
+ * be called in early boot if the cmpxchg() fast path is disabled
+ * (debug, no architecture support). In this case we will acquire the
+ * rtmutex with lock->wait_lock held. But we cannot unconditionally
+ * enable interrupts in that early boot case. So we need to use the
+ * irqsave/restore variants.
+ */
+ raw_spin_lock_irqsave(&lock->wait_lock, flags);
+ ret = __rt_mutex_slowlock_locked(lock, state);
+ raw_spin_unlock_irqrestore(&lock->wait_lock, flags);
return ret;
}
@@ -1239,7 +1255,7 @@ static __always_inline int __rt_mutex_lo
if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))
return 0;
- return rt_mutex_slowlock(lock, state, NULL, RT_MUTEX_MIN_CHAINWALK);
+ return rt_mutex_slowlock(lock, state);
}
static int __sched __rt_mutex_slowtrylock(struct rt_mutex_base *lock)
--- a/kernel/locking/rtmutex_api.c
+++ b/kernel/locking/rtmutex_api.c
@@ -342,7 +342,7 @@ int __sched rt_mutex_wait_proxy_lock(str
raw_spin_lock_irq(&lock->wait_lock);
/* sleep on the mutex */
set_current_state(TASK_INTERRUPTIBLE);
- ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter);
+ ret = rt_mutex_slowlock_block(lock, TASK_INTERRUPTIBLE, to, waiter);
/*
* try_to_take_rt_mutex() sets the waiter bit unconditionally. We might
* have to fix that up.
|
