git://bbs.cooldavid.org / net-next-2.6.git / blame
| Commit | Line | Data |
|---|---|---|
| fb1c8f93 IM |
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 | */ | |
| 19 | preempt_disable(); | |
| 20 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) | |
| 21 | while (test_and_set_bit(bitnum, addr)) { | |
| 22 | while (test_bit(bitnum, addr)) { | |
| 23 | preempt_enable(); | |
| 24 | cpu_relax(); | |
| 25 | preempt_disable(); | |
| 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 | { | |
| 37 | preempt_disable(); | |
| 38 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) | |
| 39 | if (test_and_set_bit(bitnum, addr)) { | |
| 40 | preempt_enable(); | |
| 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 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) | |
| 54 | BUG_ON(!test_bit(bitnum, addr)); | |
| 55 | smp_mb__before_clear_bit(); | |
| 56 | clear_bit(bitnum, addr); | |
| 57 | #endif | |
| 58 | preempt_enable(); | |
| 59 | __release(bitlock); | |
| 60 | } | |
| 61 | ||
| 62 | /* | |
| 63 | * Return true if the lock is held. | |
| 64 | */ | |
| 65 | static inline int bit_spin_is_locked(int bitnum, unsigned long *addr) | |
| 66 | { | |
| 67 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) | |
| 68 | return test_bit(bitnum, addr); | |
| 69 | #elif defined CONFIG_PREEMPT | |
| 70 | return preempt_count(); | |
| 71 | #else | |
| 72 | return 1; | |
| 73 | #endif | |
| 74 | } | |
| 75 | ||
| 76 | #endif /* __LINUX_BIT_SPINLOCK_H */ | |
| 77 |