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bb056c0f08
Convert {clear,set}_bit() to atomics as KVM's ucall implementation relies
on clear_bit() being atomic, they are defined in atomic.h, and the same
helpers in the kernel proper are atomic.
KVM's ucall infrastructure is the only user of clear_bit() in tools/, and
there are no true set_bit() users. tools/testing/nvdimm/ does make heavy
use of set_bit(), but that code builds into a kernel module of sorts, i.e.
pulls in all of the kernel's header and so is already getting the kernel's
atomic set_bit().
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221119013450.2643007-10-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
95 lines
1.9 KiB
C
95 lines
1.9 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 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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static inline int test_and_clear_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_and(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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