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
|
/*
* Copyright 2011 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*
* 64-bit SMP ticket spinlocks, allowing only a single CPU anywhere
* (the type definitions are in asm/spinlock_types.h)
*/
#ifndef _ASM_TILE_SPINLOCK_64_H
#define _ASM_TILE_SPINLOCK_64_H
/* Shifts and masks for the various fields in "lock". */
#define __ARCH_SPIN_CURRENT_SHIFT 17
#define __ARCH_SPIN_NEXT_MASK 0x7fff
#define __ARCH_SPIN_NEXT_OVERFLOW 0x8000
/*
* Return the "current" portion of a ticket lock value,
* i.e. the number that currently owns the lock.
*/
static inline u32 arch_spin_current(u32 val)
{
return val >> __ARCH_SPIN_CURRENT_SHIFT;
}
/*
* Return the "next" portion of a ticket lock value,
* i.e. the number that the next task to try to acquire the lock will get.
*/
static inline u32 arch_spin_next(u32 val)
{
return val & __ARCH_SPIN_NEXT_MASK;
}
/* The lock is locked if a task would have to wait to get it. */
static inline int arch_spin_is_locked(arch_spinlock_t *lock)
{
u32 val = lock->lock;
return arch_spin_current(val) != arch_spin_next(val);
}
/* Bump the current ticket so the next task owns the lock. */
static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
wmb(); /* guarantee anything modified under the lock is visible */
__insn_fetchadd4(&lock->lock, 1U << __ARCH_SPIN_CURRENT_SHIFT);
}
void arch_spin_unlock_wait(arch_spinlock_t *lock);
void arch_spin_lock_slow(arch_spinlock_t *lock, u32 val);
/* Grab the "next" ticket number and bump it atomically.
* If the current ticket is not ours, go to the slow path.
* We also take the slow path if the "next" value overflows.
*/
static inline void arch_spin_lock(arch_spinlock_t *lock)
{
u32 val = __insn_fetchadd4(&lock->lock, 1);
u32 ticket = val & (__ARCH_SPIN_NEXT_MASK | __ARCH_SPIN_NEXT_OVERFLOW);
if (unlikely(arch_spin_current(val) != ticket))
arch_spin_lock_slow(lock, ticket);
}
/* Try to get the lock, and return whether we succeeded. */
int arch_spin_trylock(arch_spinlock_t *lock);
/* We cannot take an interrupt after getting a ticket, so don't enable them. */
#define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
/*
* Read-write spinlocks, allowing multiple readers
* but only one writer.
*
* We use fetchadd() for readers, and fetchor() with the sign bit
* for writers.
*/
#define __WRITE_LOCK_BIT (1 << 31)
static inline int arch_write_val_locked(int val)
{
return val < 0; /* Optimize "val & __WRITE_LOCK_BIT". */
}
/**
* read_can_lock - would read_trylock() succeed?
* @lock: the rwlock in question.
*/
static inline int arch_read_can_lock(arch_rwlock_t *rw)
{
return !arch_write_val_locked(rw->lock);
}
/**
* write_can_lock - would write_trylock() succeed?
* @lock: the rwlock in question.
*/
static inline int arch_write_can_lock(arch_rwlock_t *rw)
{
return rw->lock == 0;
}
extern void __read_lock_failed(arch_rwlock_t *rw);
static inline void arch_read_lock(arch_rwlock_t *rw)
{
u32 val = __insn_fetchaddgez4(&rw->lock, 1);
if (unlikely(arch_write_val_locked(val)))
__read_lock_failed(rw);
}
extern void __write_lock_failed(arch_rwlock_t *rw, u32 val);
static inline void arch_write_lock(arch_rwlock_t *rw)
{
u32 val = __insn_fetchor4(&rw->lock, __WRITE_LOCK_BIT);
if (unlikely(val != 0))
__write_lock_failed(rw, val);
}
static inline void arch_read_unlock(arch_rwlock_t *rw)
{
__insn_mf();
__insn_fetchadd4(&rw->lock, -1);
}
static inline void arch_write_unlock(arch_rwlock_t *rw)
{
__insn_mf();
__insn_exch4(&rw->lock, 0); /* Avoid waiting in the write buffer. */
}
static inline int arch_read_trylock(arch_rwlock_t *rw)
{
return !arch_write_val_locked(__insn_fetchaddgez4(&rw->lock, 1));
}
static inline int arch_write_trylock(arch_rwlock_t *rw)
{
u32 val = __insn_fetchor4(&rw->lock, __WRITE_LOCK_BIT);
if (likely(val == 0))
return 1;
if (!arch_write_val_locked(val))
__insn_fetchand4(&rw->lock, ~__WRITE_LOCK_BIT);
return 0;
}
#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
#endif /* _ASM_TILE_SPINLOCK_64_H */
|
