projects / mirror_ubuntu-bionic-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
| fb1c8f93 IM |
2 | #ifndef __LINUX_BIT_SPINLOCK_H |
| 3 | #define __LINUX_BIT_SPINLOCK_H | |
| 4 | ||
| 626d6074 NP |
5 | #include <linux/kernel.h> |
| 6 | #include <linux/preempt.h> | |
| 60063497 | 7 | #include <linux/atomic.h> |
| 187f1882 | 8 | #include <linux/bug.h> |
| 626d6074 | 9 | |
| fb1c8f93 IM |
10 | /* |
| 11 | * bit-based spin_lock() | |
| 12 | * | |
| 13 | * Don't use this unless you really need to: spin_lock() and spin_unlock() | |
| 14 | * are significantly faster. | |
| 15 | */ | |
| 16 | static inline void bit_spin_lock(int bitnum, unsigned long *addr) | |
| 17 | { | |
| 18 | /* | |
| 19 | * Assuming the lock is uncontended, this never enters | |
| 20 | * the body of the outer loop. If it is contended, then | |
| 21 | * within the inner loop a non-atomic test is used to | |
| 22 | * busywait with less bus contention for a good time to | |
| 23 | * attempt to acquire the lock bit. | |
| 24 | */ | |
| 25 | preempt_disable(); | |
| 26 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) | |
| b8dc93cb | 27 | while (unlikely(test_and_set_bit_lock(bitnum, addr))) { |
| 3dd2ee48 LT |
28 | preempt_enable(); |
| 29 | do { | |
| fb1c8f93 | 30 | cpu_relax(); |
| 3dd2ee48 LT |
31 | } while (test_bit(bitnum, addr)); |
| 32 | preempt_disable(); | |
| fb1c8f93 IM |
33 | } |
| 34 | #endif | |
| 35 | __acquire(bitlock); | |
| 36 | } | |
| 37 | ||
| 38 | /* | |
| 39 | * Return true if it was acquired | |
| 40 | */ | |
| 41 | static inline int bit_spin_trylock(int bitnum, unsigned long *addr) | |
| 42 | { | |
| 43 | preempt_disable(); | |
| 44 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) | |
| b8dc93cb | 45 | if (unlikely(test_and_set_bit_lock(bitnum, addr))) { |
| fb1c8f93 IM |
46 | preempt_enable(); |
| 47 | return 0; | |
| 48 | } | |
| 49 | #endif | |
| 50 | __acquire(bitlock); | |
| 51 | return 1; | |
| 52 | } | |
| 53 | ||
| 54 | /* | |
| 55 | * bit-based spin_unlock() | |
| 56 | */ | |
| 57 | static inline void bit_spin_unlock(int bitnum, unsigned long *addr) | |
| 58 | { | |
| b8dc93cb NP |
59 | #ifdef CONFIG_DEBUG_SPINLOCK |
| 60 | BUG_ON(!test_bit(bitnum, addr)); | |
| 61 | #endif | |
| fb1c8f93 | 62 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) |
| b8dc93cb NP |
63 | clear_bit_unlock(bitnum, addr); |
| 64 | #endif | |
| 65 | preempt_enable(); | |
| 66 | __release(bitlock); | |
| 67 | } | |
| 68 | ||
| 69 | /* | |
| 70 | * bit-based spin_unlock() | |
| 71 | * non-atomic version, which can be used eg. if the bit lock itself is | |
| 72 | * protecting the rest of the flags in the word. | |
| 73 | */ | |
| 74 | static inline void __bit_spin_unlock(int bitnum, unsigned long *addr) | |
| 75 | { | |
| 76 | #ifdef CONFIG_DEBUG_SPINLOCK | |
| fb1c8f93 | 77 | BUG_ON(!test_bit(bitnum, addr)); |
| b8dc93cb NP |
78 | #endif |
| 79 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) | |
| 80 | __clear_bit_unlock(bitnum, addr); | |
| fb1c8f93 IM |
81 | #endif |
| 82 | preempt_enable(); | |
| 83 | __release(bitlock); | |
| 84 | } | |
| 85 | ||
| 86 | /* | |
| 87 | * Return true if the lock is held. | |
| 88 | */ | |
| 89 | static inline int bit_spin_is_locked(int bitnum, unsigned long *addr) | |
| 90 | { | |
| 91 | #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) | |
| 92 | return test_bit(bitnum, addr); | |
| bdd4e85d | 93 | #elif defined CONFIG_PREEMPT_COUNT |
| fb1c8f93 IM |
94 | return preempt_count(); |
| 95 | #else | |
| 96 | return 1; | |
| 97 | #endif | |
| 98 | } | |
| 99 | ||
| 100 | #endif /* __LINUX_BIT_SPINLOCK_H */ | |
| 101 |