| 1 |
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| 2 | #ifndef _ASM_GENERIC_BITOPS_LOCK_H_
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| 3 | #define _ASM_GENERIC_BITOPS_LOCK_H_
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| 4 |
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| 5 | #include <linux/atomic.h>
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| 6 | #include <linux/compiler.h>
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| 7 | #include <asm/barrier.h>
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| 8 |
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| 9 | |
| 10 | * arch_test_and_set_bit_lock - Set a bit and return its old value, for lock
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| 11 | * @nr: Bit to set
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| 12 | * @addr: Address to count from
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| 13 | *
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| 14 | * This operation is atomic and provides acquire barrier semantics if
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| 15 | * the returned value is 0.
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| 16 | * It can be used to implement bit locks.
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| 17 |
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| 18 | static __always_inline int
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| 19 | arch_test_and_set_bit_lock(unsigned int nr, volatile unsigned long *addr)
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| 20 | {
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| 21 | long old;
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| 22 | unsigned long mask = BIT_MASK(nr);
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| 23 |
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| 24 | addr += BIT_WORD(nr);
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| 25 | if (READ_ONCE(*addr) & mask)
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| 26 | return 1;
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| 27 |
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| 28 | old = raw_atomic_long_fetch_or_acquire(mask, (atomic_long_t *)addr);
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| 29 | return !!(old & mask);
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| 30 | }
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| 31 |
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| 32 |
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| 33 | |
| 34 | * arch_clear_bit_unlock - Clear a bit in memory, for unlock
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| 35 | * @nr: the bit to set
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| 36 | * @addr: the address to start counting from
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| 37 | *
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| 38 | * This operation is atomic and provides release barrier semantics.
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| 39 |
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| 40 | static __always_inline void
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| 41 | arch_clear_bit_unlock(unsigned int nr, volatile unsigned long *addr)
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| 42 | {
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| 43 | addr += BIT_WORD(nr);
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| 44 | raw_atomic_long_fetch_andnot_release(BIT_MASK(nr), (atomic_long_t *)addr);
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| 45 | }
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| 46 |
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| 47 | |
| 48 | * arch___clear_bit_unlock - Clear a bit in memory, for unlock
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| 49 | * @nr: the bit to set
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| 50 | * @addr: the address to start counting from
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| 51 | *
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| 52 | * A weaker form of clear_bit_unlock() as used by __bit_lock_unlock(). If all
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| 53 | * the bits in the word are protected by this lock some archs can use weaker
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| 54 | * ops to safely unlock.
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| 55 | *
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| 56 | * See for example x86's implementation.
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| 57 |
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| 58 | static inline void
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| 59 | arch___clear_bit_unlock(unsigned int nr, volatile unsigned long *addr)
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| 60 | {
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| 61 | unsigned long old;
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| 62 |
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| 63 | addr += BIT_WORD(nr);
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| 64 | old = READ_ONCE(*addr);
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| 65 | old &= ~BIT_MASK(nr);
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| 66 | raw_atomic_long_set_release((atomic_long_t *)addr, old);
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| 67 | }
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| 68 |
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| 69 | #ifndef arch_xor_unlock_is_negative_byte
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| 70 | static inline bool arch_xor_unlock_is_negative_byte(unsigned long mask,
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| 71 | volatile unsigned long *p)
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| 72 | {
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| 73 | long old;
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| 74 |
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| 75 | old = raw_atomic_long_fetch_xor_release(mask, (atomic_long_t *)p);
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| 76 | return !!(old & BIT(7));
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| 77 | }
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| 78 | #endif
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| 79 |
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| 80 | #include <asm-generic/bitops/instrumented-lock.h>
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| 81 |
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| 82 | #endif
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