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cf4694be2b
Add x86 and generic implementations of atomic_test_and_set_bit() to allow
KVM selftests to atomically manage bitmaps.
Note, the generic version is taken from arch_test_and_set_bit() as of
commit 415d832497 ("locking/atomic: Make test_and_*_bit() ordered on
failure").
Signed-off-by: Peter Gonda <pgonda@google.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-5-seanjc@google.com
85 lines
1.7 KiB
C
85 lines
1.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __TOOLS_ASM_GENERIC_ATOMIC_H
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#define __TOOLS_ASM_GENERIC_ATOMIC_H
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#include <linux/compiler.h>
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#include <linux/types.h>
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#include <linux/bitops.h>
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/*
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* Atomic operations that C can't guarantee us. Useful for
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* resource counting etc..
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*
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* Excerpts obtained from the Linux kernel sources.
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*/
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#define ATOMIC_INIT(i) { (i) }
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/**
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* atomic_read - read atomic variable
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* @v: pointer of type atomic_t
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*
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* Atomically reads the value of @v.
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*/
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static inline int atomic_read(const atomic_t *v)
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{
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return READ_ONCE((v)->counter);
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}
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/**
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* atomic_set - set atomic variable
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* @v: pointer of type atomic_t
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* @i: required value
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*
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* Atomically sets the value of @v to @i.
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*/
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static inline void atomic_set(atomic_t *v, int i)
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{
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v->counter = i;
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}
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/**
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* atomic_inc - increment atomic variable
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* @v: pointer of type atomic_t
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*
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* Atomically increments @v by 1.
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*/
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static inline void atomic_inc(atomic_t *v)
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{
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__sync_add_and_fetch(&v->counter, 1);
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}
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/**
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* atomic_dec_and_test - decrement and test
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* @v: pointer of type atomic_t
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*
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* Atomically decrements @v by 1 and
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* returns true if the result is 0, or false for all other
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* cases.
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*/
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static inline int atomic_dec_and_test(atomic_t *v)
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{
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return __sync_sub_and_fetch(&v->counter, 1) == 0;
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}
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#define cmpxchg(ptr, oldval, newval) \
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__sync_val_compare_and_swap(ptr, oldval, newval)
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static inline int atomic_cmpxchg(atomic_t *v, int oldval, int newval)
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{
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return cmpxchg(&(v)->counter, oldval, newval);
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}
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static inline int atomic_test_and_set_bit(long nr, unsigned long *addr)
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{
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unsigned long mask = BIT_MASK(nr);
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long old;
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addr += BIT_WORD(nr);
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old = __sync_fetch_and_or(addr, mask);
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return !!(old & mask);
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}
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#endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */
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