sync_bitops.h
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#ifndef _ASM_X86_SYNC_BITOPS_H
#define _ASM_X86_SYNC_BITOPS_H
/*
* Copyright 1992, Linus Torvalds.
*/
/*
* These have to be done with inline assembly: that way the bit-setting
* is guaranteed to be atomic. All bit operations return 0 if the bit
* was cleared before the operation and != 0 if it was not.
*
* bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
*/
#define ADDR (*(volatile long *)addr)
/**
* sync_set_bit - Atomically set a bit in memory
* @nr: the bit to set
* @addr: the address to start counting from
*
* This function is atomic and may not be reordered. See __set_bit()
* if you do not require the atomic guarantees.
*
* Note that @nr may be almost arbitrarily large; this function is not
* restricted to acting on a single-word quantity.
*/
static inline void sync_set_bit(int nr, volatile unsigned long *addr)
{
asm volatile("lock; btsl %1,%0"
: "+m" (ADDR)
: "Ir" (nr)
: "memory");
}
/**
* sync_clear_bit - Clears a bit in memory
* @nr: Bit to clear
* @addr: Address to start counting from
*
* sync_clear_bit() is atomic and may not be reordered. However, it does
* not contain a memory barrier, so if it is used for locking purposes,
* you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
* in order to ensure changes are visible on other processors.
*/
static inline void sync_clear_bit(int nr, volatile unsigned long *addr)
{
asm volatile("lock; btrl %1,%0"
: "+m" (ADDR)
: "Ir" (nr)
: "memory");
}
/**
* sync_change_bit - Toggle a bit in memory
* @nr: Bit to change
* @addr: Address to start counting from
*
* sync_change_bit() is atomic and may not be reordered.
* Note that @nr may be almost arbitrarily large; this function is not
* restricted to acting on a single-word quantity.
*/
static inline void sync_change_bit(int nr, volatile unsigned long *addr)
{
asm volatile("lock; btcl %1,%0"
: "+m" (ADDR)
: "Ir" (nr)
: "memory");
}
/**
* sync_test_and_set_bit - Set a bit and return its old value
* @nr: Bit to set
* @addr: Address to count from
*
* This operation is atomic and cannot be reordered.
* It also implies a memory barrier.
*/
static inline int sync_test_and_set_bit(int nr, volatile unsigned long *addr)
{
int oldbit;
asm volatile("lock; btsl %2,%1\n\tsbbl %0,%0"
: "=r" (oldbit), "+m" (ADDR)
: "Ir" (nr) : "memory");
return oldbit;
}
/**
* sync_test_and_clear_bit - Clear a bit and return its old value
* @nr: Bit to clear
* @addr: Address to count from
*
* This operation is atomic and cannot be reordered.
* It also implies a memory barrier.
*/
static inline int sync_test_and_clear_bit(int nr, volatile unsigned long *addr)
{
int oldbit;
asm volatile("lock; btrl %2,%1\n\tsbbl %0,%0"
: "=r" (oldbit), "+m" (ADDR)
: "Ir" (nr) : "memory");
return oldbit;
}
/**
* sync_test_and_change_bit - Change a bit and return its old value
* @nr: Bit to change
* @addr: Address to count from
*
* This operation is atomic and cannot be reordered.
* It also implies a memory barrier.
*/
static inline int sync_test_and_change_bit(int nr, volatile unsigned long *addr)
{
int oldbit;
asm volatile("lock; btcl %2,%1\n\tsbbl %0,%0"
: "=r" (oldbit), "+m" (ADDR)
: "Ir" (nr) : "memory");
return oldbit;
}
#define sync_test_bit(nr, addr) test_bit(nr, addr)
#undef ADDR
#endif /* _ASM_X86_SYNC_BITOPS_H */