mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-26 04:25:27 +08:00
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>
96 lines
1.9 KiB
C
96 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef __TOOLS_ASM_GENERIC_ATOMIC_H
|
|
#define __TOOLS_ASM_GENERIC_ATOMIC_H
|
|
|
|
#include <linux/compiler.h>
|
|
#include <linux/types.h>
|
|
#include <linux/bitops.h>
|
|
|
|
/*
|
|
* Atomic operations that C can't guarantee us. Useful for
|
|
* resource counting etc..
|
|
*
|
|
* Excerpts obtained from the Linux kernel sources.
|
|
*/
|
|
|
|
#define ATOMIC_INIT(i) { (i) }
|
|
|
|
/**
|
|
* atomic_read - read atomic variable
|
|
* @v: pointer of type atomic_t
|
|
*
|
|
* Atomically reads the value of @v.
|
|
*/
|
|
static inline int atomic_read(const atomic_t *v)
|
|
{
|
|
return READ_ONCE((v)->counter);
|
|
}
|
|
|
|
/**
|
|
* atomic_set - set atomic variable
|
|
* @v: pointer of type atomic_t
|
|
* @i: required value
|
|
*
|
|
* Atomically sets the value of @v to @i.
|
|
*/
|
|
static inline void atomic_set(atomic_t *v, int i)
|
|
{
|
|
v->counter = i;
|
|
}
|
|
|
|
/**
|
|
* atomic_inc - increment atomic variable
|
|
* @v: pointer of type atomic_t
|
|
*
|
|
* Atomically increments @v by 1.
|
|
*/
|
|
static inline void atomic_inc(atomic_t *v)
|
|
{
|
|
__sync_add_and_fetch(&v->counter, 1);
|
|
}
|
|
|
|
/**
|
|
* atomic_dec_and_test - decrement and test
|
|
* @v: pointer of type atomic_t
|
|
*
|
|
* Atomically decrements @v by 1 and
|
|
* returns true if the result is 0, or false for all other
|
|
* cases.
|
|
*/
|
|
static inline int atomic_dec_and_test(atomic_t *v)
|
|
{
|
|
return __sync_sub_and_fetch(&v->counter, 1) == 0;
|
|
}
|
|
|
|
#define cmpxchg(ptr, oldval, newval) \
|
|
__sync_val_compare_and_swap(ptr, oldval, newval)
|
|
|
|
static inline int atomic_cmpxchg(atomic_t *v, int oldval, int newval)
|
|
{
|
|
return cmpxchg(&(v)->counter, oldval, newval);
|
|
}
|
|
|
|
static inline int test_and_set_bit(long nr, unsigned long *addr)
|
|
{
|
|
unsigned long mask = BIT_MASK(nr);
|
|
long old;
|
|
|
|
addr += BIT_WORD(nr);
|
|
|
|
old = __sync_fetch_and_or(addr, mask);
|
|
return !!(old & mask);
|
|
}
|
|
|
|
static inline int test_and_clear_bit(long nr, unsigned long *addr)
|
|
{
|
|
unsigned long mask = BIT_MASK(nr);
|
|
long old;
|
|
|
|
addr += BIT_WORD(nr);
|
|
|
|
old = __sync_fetch_and_and(addr, ~mask);
|
|
return !!(old & mask);
|
|
}
|
|
|
|
#endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */
|