projects / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| fb1c8f93 IM |
1 | #ifndef __LINUX_BIT_SPINLOCK_H |
| 2 | #define __LINUX_BIT_SPINLOCK_H | |
| 3 | ||
| 626d6074 NP |
4 | #include <linux/kernel.h> |
| 5 | #include <linux/preempt.h> | |
| 60063497 | 6 | #include <linux/atomic.h> |
| 187f1882 | 7 | #include <linux/bug.h> |
| 626d6074 | 8 | |
| fb1c8f93 IM |
9 | /* |
| 10 | * bit-based spin_lock() | |
| 11 | * | |
| 12 | * Don't use this unless you really need to: spin_lock() and spin_unlock() | |
| 13 | * are significantly faster. | |
| 14 | */ | |
| 15 | static inline void bit_spin_lock(int bitnum, unsigned long *addr) | |
| 16 | { | |
| 17 | /* | |
| 18 | * Assuming the lock is uncontended, this never enters | |
| 19 | * the body of the outer loop. If it is contended, then | |
| 20 | * within the inner loop a non-atomic test is used to | |
| 21 | * busywait with less bus contention for a good time to | |
| 22 | * attempt to acquire the lock bit. | |
| 23 | */ | |
| 24 | preempt_disable(); | |
| 25 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) | |
| b8dc93cb | 26 | while (unlikely(test_and_set_bit_lock(bitnum, addr))) { |
| 3dd2ee48 LT |
27 | preempt_enable(); |
| 28 | do { | |
| fb1c8f93 | 29 | cpu_relax(); |
| 3dd2ee48 LT |
30 | } while (test_bit(bitnum, addr)); |
| 31 | preempt_disable(); | |
| fb1c8f93 IM |
32 | } |
| 33 | #endif | |
| 34 | __acquire(bitlock); | |
| 35 | } | |
| 36 | ||
| 37 | /* | |
| 38 | * Return true if it was acquired | |
| 39 | */ | |
| 40 | static inline int bit_spin_trylock(int bitnum, unsigned long *addr) | |
| 41 | { | |
| 42 | preempt_disable(); | |
| 43 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) | |
| b8dc93cb | 44 | if (unlikely(test_and_set_bit_lock(bitnum, addr))) { |
| fb1c8f93 IM |
45 | preempt_enable(); |
| 46 | return 0; | |
| 47 | } | |
| 48 | #endif | |
| 49 | __acquire(bitlock); | |
| 50 | return 1; | |
| 51 | } | |
| 52 | ||
| 53 | /* | |
| 54 | * bit-based spin_unlock() | |
| 55 | */ | |
| 56 | static inline void bit_spin_unlock(int bitnum, unsigned long *addr) | |
| 57 | { | |
| b8dc93cb NP |
58 | #ifdef CONFIG_DEBUG_SPINLOCK |
| 59 | BUG_ON(!test_bit(bitnum, addr)); | |
| 60 | #endif | |
| fb1c8f93 | 61 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) |
| b8dc93cb NP |
62 | clear_bit_unlock(bitnum, addr); |
| 63 | #endif | |
| 64 | preempt_enable(); | |
| 65 | __release(bitlock); | |
| 66 | } | |
| 67 | ||
| 68 | /* | |
| 69 | * bit-based spin_unlock() | |
| 70 | * non-atomic version, which can be used eg. if the bit lock itself is | |
| 71 | * protecting the rest of the flags in the word. | |
| 72 | */ | |
| 73 | static inline void __bit_spin_unlock(int bitnum, unsigned long *addr) | |
| 74 | { | |
| 75 | #ifdef CONFIG_DEBUG_SPINLOCK | |
| fb1c8f93 | 76 | BUG_ON(!test_bit(bitnum, addr)); |
| b8dc93cb NP |
77 | #endif |
| 78 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) | |
| 79 | __clear_bit_unlock(bitnum, addr); | |
| fb1c8f93 IM |
80 | #endif |
| 81 | preempt_enable(); | |
| 82 | __release(bitlock); | |
| 83 | } | |
| 84 | ||
| 85 | /* | |
| 86 | * Return true if the lock is held. | |
| 87 | */ | |
| 88 | static inline int bit_spin_is_locked(int bitnum, unsigned long *addr) | |
| 89 | { | |
| 90 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) | |
| 91 | return test_bit(bitnum, addr); | |
| bdd4e85d | 92 | #elif defined CONFIG_PREEMPT_COUNT |
| fb1c8f93 IM |
93 | return preempt_count(); |
| 94 | #else | |
| 95 | return 1; | |
| 96 | #endif | |
| 97 | } | |
| 98 | ||
| 99 | #endif /* __LINUX_BIT_SPINLOCK_H */ | |
| 100 |