source: mainline/kernel/arch/ia32/src/atomic.S@ f1380b7

#
# Copyright (c) 2001-2004 Jakub Jermar
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#
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# modification, are permitted provided that the following conditions
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#
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#include <abi/asmtool.h>

.text

#ifdef CONFIG_SMP

#
# This is a bus-and-hyperthreading-friendly implementation of spinlock
#
FUNCTION_BEGIN(spinlock_arch)
        pushl %eax
        pushl %ebx

        movl 12(%esp),%ebx

0:
        pause                   # Pentium 4's with HT love this instruction
        movl (%ebx),%eax
        testl %eax,%eax
        jnz 0b                  # lightweight looping while it is locked
        incl %eax
        xchgl %eax,(%ebx)       # now use the atomic operation
        testl %eax,%eax
        jnz 0b

        popl %ebx
        popl %eax
        ret
FUNCTION_END(spinlock_arch)

#endif