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175 lines
5.2 KiB
175 lines
5.2 KiB
/* SPDX-License-Identifier: GPL-2.0-only */ |
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#ifndef __ASM_GENERIC_BITOPS_GENERIC_NON_ATOMIC_H |
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#define __ASM_GENERIC_BITOPS_GENERIC_NON_ATOMIC_H |
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#include <linux/bits.h> |
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#include <asm/barrier.h> |
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#ifndef _LINUX_BITOPS_H |
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#error only <linux/bitops.h> can be included directly |
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#endif |
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/* |
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* Generic definitions for bit operations, should not be used in regular code |
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* directly. |
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*/ |
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/** |
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* generic___set_bit - Set a bit in memory |
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* @nr: the bit to set |
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* @addr: the address to start counting from |
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* |
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* Unlike set_bit(), this function is non-atomic and may be reordered. |
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* If it's called on the same region of memory simultaneously, the effect |
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* may be that only one operation succeeds. |
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*/ |
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static __always_inline void |
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generic___set_bit(unsigned long nr, volatile unsigned long *addr) |
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{ |
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unsigned long mask = BIT_MASK(nr); |
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unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); |
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*p |= mask; |
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} |
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static __always_inline void |
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generic___clear_bit(unsigned long nr, volatile unsigned long *addr) |
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{ |
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unsigned long mask = BIT_MASK(nr); |
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unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); |
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*p &= ~mask; |
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} |
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/** |
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* generic___change_bit - Toggle a bit in memory |
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* @nr: the bit to change |
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* @addr: the address to start counting from |
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* |
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* Unlike change_bit(), this function is non-atomic and may be reordered. |
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* If it's called on the same region of memory simultaneously, the effect |
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* may be that only one operation succeeds. |
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*/ |
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static __always_inline void |
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generic___change_bit(unsigned long nr, volatile unsigned long *addr) |
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{ |
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unsigned long mask = BIT_MASK(nr); |
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unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); |
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*p ^= mask; |
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} |
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/** |
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* generic___test_and_set_bit - Set a bit and return its old value |
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* @nr: Bit to set |
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* @addr: Address to count from |
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* |
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* This operation is non-atomic and can be reordered. |
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* If two examples of this operation race, one can appear to succeed |
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* but actually fail. You must protect multiple accesses with a lock. |
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*/ |
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static __always_inline bool |
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generic___test_and_set_bit(unsigned long nr, volatile unsigned long *addr) |
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{ |
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unsigned long mask = BIT_MASK(nr); |
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unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); |
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unsigned long old = *p; |
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*p = old | mask; |
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return (old & mask) != 0; |
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} |
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/** |
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* generic___test_and_clear_bit - Clear a bit and return its old value |
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* @nr: Bit to clear |
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* @addr: Address to count from |
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* |
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* This operation is non-atomic and can be reordered. |
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* If two examples of this operation race, one can appear to succeed |
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* but actually fail. You must protect multiple accesses with a lock. |
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*/ |
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static __always_inline bool |
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generic___test_and_clear_bit(unsigned long nr, volatile unsigned long *addr) |
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{ |
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unsigned long mask = BIT_MASK(nr); |
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unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); |
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unsigned long old = *p; |
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*p = old & ~mask; |
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return (old & mask) != 0; |
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} |
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/* WARNING: non atomic and it can be reordered! */ |
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static __always_inline bool |
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generic___test_and_change_bit(unsigned long nr, volatile unsigned long *addr) |
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{ |
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unsigned long mask = BIT_MASK(nr); |
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unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); |
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unsigned long old = *p; |
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*p = old ^ mask; |
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return (old & mask) != 0; |
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} |
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/** |
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* generic_test_bit - Determine whether a bit is set |
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* @nr: bit number to test |
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* @addr: Address to start counting from |
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*/ |
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static __always_inline bool |
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generic_test_bit(unsigned long nr, const volatile unsigned long *addr) |
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{ |
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/* |
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* Unlike the bitops with the '__' prefix above, this one *is* atomic, |
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* so `volatile` must always stay here with no cast-aways. See |
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* `Documentation/atomic_bitops.txt` for the details. |
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*/ |
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return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1))); |
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} |
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/** |
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* generic_test_bit_acquire - Determine, with acquire semantics, whether a bit is set |
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* @nr: bit number to test |
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* @addr: Address to start counting from |
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*/ |
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static __always_inline bool |
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generic_test_bit_acquire(unsigned long nr, const volatile unsigned long *addr) |
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{ |
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unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr); |
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return 1UL & (smp_load_acquire(p) >> (nr & (BITS_PER_LONG-1))); |
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} |
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/* |
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* const_*() definitions provide good compile-time optimizations when |
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* the passed arguments can be resolved at compile time. |
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*/ |
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#define const___set_bit generic___set_bit |
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#define const___clear_bit generic___clear_bit |
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#define const___change_bit generic___change_bit |
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#define const___test_and_set_bit generic___test_and_set_bit |
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#define const___test_and_clear_bit generic___test_and_clear_bit |
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#define const___test_and_change_bit generic___test_and_change_bit |
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#define const_test_bit_acquire generic_test_bit_acquire |
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/** |
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* const_test_bit - Determine whether a bit is set |
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* @nr: bit number to test |
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* @addr: Address to start counting from |
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* |
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* A version of generic_test_bit() which discards the `volatile` qualifier to |
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* allow a compiler to optimize code harder. Non-atomic and to be called only |
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* for testing compile-time constants, e.g. by the corresponding macros, not |
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* directly from "regular" code. |
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*/ |
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static __always_inline bool |
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const_test_bit(unsigned long nr, const volatile unsigned long *addr) |
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{ |
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const unsigned long *p = (const unsigned long *)addr + BIT_WORD(nr); |
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unsigned long mask = BIT_MASK(nr); |
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unsigned long val = *p; |
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return !!(val & mask); |
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} |
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#endif /* __ASM_GENERIC_BITOPS_GENERIC_NON_ATOMIC_H */
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