ReactOS  0.4.13-dev-464-g6b95727
bit_spinlock.h
Go to the documentation of this file.
1 #ifndef __LINUX_BIT_SPINLOCK_H
2 #define __LINUX_BIT_SPINLOCK_H
3 
4 /*
5  * bit-based spin_lock()
6  *
7  * Don't use this unless you really need to: spin_lock() and spin_unlock()
8  * are significantly faster.
9  */
10 static inline void bit_spin_lock(int bitnum, unsigned long *addr)
11 {
12  /*
13  * Assuming the lock is uncontended, this never enters
14  * the body of the outer loop. If it is contended, then
15  * within the inner loop a non-atomic test is used to
16  * busywait with less bus contention for a good time to
17  * attempt to acquire the lock bit.
18  */
20 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
21  while (unlikely(test_and_set_bit_lock(bitnum, addr))) {
22  while (test_bit(bitnum, addr)) {
24  cpu_relax();
26  }
27  }
28 #endif
29  __acquire(bitlock);
30 }
31 
32 /*
33  * Return true if it was acquired
34  */
35 static inline int bit_spin_trylock(int bitnum, unsigned long *addr)
36 {
38 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
39  if (unlikely(test_and_set_bit_lock(bitnum, addr))) {
41  return 0;
42  }
43 #endif
44  __acquire(bitlock);
45  return 1;
46 }
47 
48 /*
49  * bit-based spin_unlock()
50  */
51 static inline void bit_spin_unlock(int bitnum, unsigned long *addr)
52 {
53 #ifdef CONFIG_DEBUG_SPINLOCK
54  BUG_ON(!test_bit(bitnum, addr));
55 #endif
56 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
57  clear_bit_unlock(bitnum, addr);
58 #endif
60  __release(bitlock);
61 }
62 
63 /*
64  * bit-based spin_unlock()
65  * non-atomic version, which can be used eg. if the bit lock itself is
66  * protecting the rest of the flags in the word.
67  */
68 static inline void __bit_spin_unlock(int bitnum, unsigned long *addr)
69 {
70 #ifdef CONFIG_DEBUG_SPINLOCK
71  BUG_ON(!test_bit(bitnum, addr));
72 #endif
73 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
74  __clear_bit_unlock(bitnum, addr);
75 #endif
77  __release(bitlock);
78 }
79 
80 /*
81  * Return true if the lock is held.
82  */
83 static inline int bit_spin_is_locked(int bitnum, unsigned long *addr)
84 {
85 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
86  return test_bit(bitnum, addr);
87 #elif defined CONFIG_PREEMPT
88  return preempt_count();
89 #else
90  return 1;
91 #endif
92 }
93 
94 #endif /* __LINUX_BIT_SPINLOCK_H */
95 
#define preempt_disable()
Definition: types.h:105
static void __bit_spin_unlock(int bitnum, unsigned long *addr)
Definition: bit_spinlock.h:68
static void bit_spin_unlock(int bitnum, unsigned long *addr)
Definition: bit_spinlock.h:51
static void bit_spin_lock(int bitnum, unsigned long *addr)
Definition: bit_spinlock.h:10
static int bit_spin_is_locked(int bitnum, unsigned long *addr)
Definition: bit_spinlock.h:83
static int test_bit(int nr, volatile const unsigned long *addr)
Definition: module.h:381
#define __release(x)
Definition: types.h:102
#define BUG_ON(c)
Definition: module.h:253
#define preempt_enable()
Definition: types.h:104
GLenum const GLvoid * addr
Definition: glext.h:9621
#define __acquire(x)
Definition: types.h:101
static int bit_spin_trylock(int bitnum, unsigned long *addr)
Definition: bit_spinlock.h:35
#define unlikely
Definition: module.h:262