1 /* SPDX-License-Identifier: GPL-2.0 */ <<
2 #ifndef __LINUX_BIT_SPINLOCK_H 1 #ifndef __LINUX_BIT_SPINLOCK_H
3 #define __LINUX_BIT_SPINLOCK_H 2 #define __LINUX_BIT_SPINLOCK_H
4 3
5 #include <linux/kernel.h> <<
6 #include <linux/preempt.h> <<
7 #include <linux/atomic.h> <<
8 #include <linux/bug.h> <<
9 <<
10 /* 4 /*
11 * bit-based spin_lock() 5 * bit-based spin_lock()
12 * 6 *
13 * Don't use this unless you really need to: s 7 * Don't use this unless you really need to: spin_lock() and spin_unlock()
14 * are significantly faster. 8 * are significantly faster.
15 */ 9 */
16 static inline void bit_spin_lock(int bitnum, u 10 static inline void bit_spin_lock(int bitnum, unsigned long *addr)
17 { 11 {
18 /* 12 /*
19 * Assuming the lock is uncontended, t 13 * Assuming the lock is uncontended, this never enters
20 * the body of the outer loop. If it i 14 * the body of the outer loop. If it is contended, then
21 * within the inner loop a non-atomic 15 * within the inner loop a non-atomic test is used to
22 * busywait with less bus contention f 16 * busywait with less bus contention for a good time to
23 * attempt to acquire the lock bit. 17 * attempt to acquire the lock bit.
24 */ 18 */
25 preempt_disable(); 19 preempt_disable();
26 #if defined(CONFIG_SMP) || defined(CONFIG_DEBU 20 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
27 while (unlikely(test_and_set_bit_lock( 21 while (unlikely(test_and_set_bit_lock(bitnum, addr))) {
28 preempt_enable(); !! 22 while (test_bit(bitnum, addr)) {
29 do { !! 23 preempt_enable();
30 cpu_relax(); 24 cpu_relax();
31 } while (test_bit(bitnum, addr !! 25 preempt_disable();
32 preempt_disable(); !! 26 }
33 } 27 }
34 #endif 28 #endif
35 __acquire(bitlock); 29 __acquire(bitlock);
36 } 30 }
37 31
38 /* 32 /*
39 * Return true if it was acquired 33 * Return true if it was acquired
40 */ 34 */
41 static inline int bit_spin_trylock(int bitnum, 35 static inline int bit_spin_trylock(int bitnum, unsigned long *addr)
42 { 36 {
43 preempt_disable(); 37 preempt_disable();
44 #if defined(CONFIG_SMP) || defined(CONFIG_DEBU 38 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
45 if (unlikely(test_and_set_bit_lock(bit 39 if (unlikely(test_and_set_bit_lock(bitnum, addr))) {
46 preempt_enable(); 40 preempt_enable();
47 return 0; 41 return 0;
48 } 42 }
49 #endif 43 #endif
50 __acquire(bitlock); 44 __acquire(bitlock);
51 return 1; 45 return 1;
52 } 46 }
53 47
54 /* 48 /*
55 * bit-based spin_unlock() 49 * bit-based spin_unlock()
56 */ 50 */
57 static inline void bit_spin_unlock(int bitnum, 51 static inline void bit_spin_unlock(int bitnum, unsigned long *addr)
58 { 52 {
59 #ifdef CONFIG_DEBUG_SPINLOCK 53 #ifdef CONFIG_DEBUG_SPINLOCK
60 BUG_ON(!test_bit(bitnum, addr)); 54 BUG_ON(!test_bit(bitnum, addr));
61 #endif 55 #endif
62 #if defined(CONFIG_SMP) || defined(CONFIG_DEBU 56 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
63 clear_bit_unlock(bitnum, addr); 57 clear_bit_unlock(bitnum, addr);
64 #endif 58 #endif
65 preempt_enable(); 59 preempt_enable();
66 __release(bitlock); 60 __release(bitlock);
67 } 61 }
68 62
69 /* 63 /*
70 * bit-based spin_unlock() 64 * bit-based spin_unlock()
71 * non-atomic version, which can be used eg. 65 * non-atomic version, which can be used eg. if the bit lock itself is
72 * protecting the rest of the flags in the wo 66 * protecting the rest of the flags in the word.
73 */ 67 */
74 static inline void __bit_spin_unlock(int bitnu 68 static inline void __bit_spin_unlock(int bitnum, unsigned long *addr)
75 { 69 {
76 #ifdef CONFIG_DEBUG_SPINLOCK 70 #ifdef CONFIG_DEBUG_SPINLOCK
77 BUG_ON(!test_bit(bitnum, addr)); 71 BUG_ON(!test_bit(bitnum, addr));
78 #endif 72 #endif
79 #if defined(CONFIG_SMP) || defined(CONFIG_DEBU 73 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
80 __clear_bit_unlock(bitnum, addr); 74 __clear_bit_unlock(bitnum, addr);
81 #endif 75 #endif
82 preempt_enable(); 76 preempt_enable();
83 __release(bitlock); 77 __release(bitlock);
84 } 78 }
85 79
86 /* 80 /*
87 * Return true if the lock is held. 81 * Return true if the lock is held.
88 */ 82 */
89 static inline int bit_spin_is_locked(int bitnu 83 static inline int bit_spin_is_locked(int bitnum, unsigned long *addr)
90 { 84 {
91 #if defined(CONFIG_SMP) || defined(CONFIG_DEBU 85 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
92 return test_bit(bitnum, addr); 86 return test_bit(bitnum, addr);
93 #elif defined CONFIG_PREEMPT_COUNT !! 87 #elif defined CONFIG_PREEMPT
94 return preempt_count(); 88 return preempt_count();
95 #else 89 #else
96 return 1; 90 return 1;
97 #endif 91 #endif
98 } 92 }
99 93
100 #endif /* __LINUX_BIT_SPINLOCK_H */ 94 #endif /* __LINUX_BIT_SPINLOCK_H */
101 95
102 96
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.