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
|
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_GENERIC_BITOPS_LOCK_H_
#define _ASM_GENERIC_BITOPS_LOCK_H_
#include <linux/atomic.h>
#include <linux/compiler.h>
#include <asm/barrier.h>
/**
* arch_test_and_set_bit_lock - Set a bit and return its old value, for lock
* @nr: Bit to set
* @addr: Address to count from
*
* This operation is atomic and provides acquire barrier semantics if
* the returned value is 0.
* It can be used to implement bit locks.
*/
static __always_inline int
arch_test_and_set_bit_lock(unsigned int nr, volatile unsigned long *p)
{
long old;
unsigned long mask = BIT_MASK(nr);
p += BIT_WORD(nr);
if (READ_ONCE(*p) & mask)
return 1;
old = raw_atomic_long_fetch_or_acquire(mask, (atomic_long_t *)p);
return !!(old & mask);
}
/**
* arch_clear_bit_unlock - Clear a bit in memory, for unlock
* @nr: the bit to set
* @addr: the address to start counting from
*
* This operation is atomic and provides release barrier semantics.
*/
static __always_inline void
arch_clear_bit_unlock(unsigned int nr, volatile unsigned long *p)
{
p += BIT_WORD(nr);
raw_atomic_long_fetch_andnot_release(BIT_MASK(nr), (atomic_long_t *)p);
}
/**
* arch___clear_bit_unlock - Clear a bit in memory, for unlock
* @nr: the bit to set
* @addr: the address to start counting from
*
* A weaker form of clear_bit_unlock() as used by __bit_lock_unlock(). If all
* the bits in the word are protected by this lock some archs can use weaker
* ops to safely unlock.
*
* See for example x86's implementation.
*/
static inline void
arch___clear_bit_unlock(unsigned int nr, volatile unsigned long *p)
{
unsigned long old;
p += BIT_WORD(nr);
old = READ_ONCE(*p);
old &= ~BIT_MASK(nr);
raw_atomic_long_set_release((atomic_long_t *)p, old);
}
/**
* arch_clear_bit_unlock_is_negative_byte - Clear a bit in memory and test if bottom
* byte is negative, for unlock.
* @nr: the bit to clear
* @addr: the address to start counting from
*
* This is a bit of a one-trick-pony for the filemap code, which clears
* PG_locked and tests PG_waiters,
*/
#ifndef arch_clear_bit_unlock_is_negative_byte
static inline bool arch_clear_bit_unlock_is_negative_byte(unsigned int nr,
volatile unsigned long *p)
{
long old;
unsigned long mask = BIT_MASK(nr);
p += BIT_WORD(nr);
old = raw_atomic_long_fetch_andnot_release(mask, (atomic_long_t *)p);
return !!(old & BIT(7));
}
#define arch_clear_bit_unlock_is_negative_byte arch_clear_bit_unlock_is_negative_byte
#endif
#include <asm-generic/bitops/instrumented-lock.h>
#endif /* _ASM_GENERIC_BITOPS_LOCK_H_ */
|
