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linux
xen/arm: sync_bitops
sync_bitops functions are equivalent to the SMP implementation of the
original functions, independently from CONFIG_SMP being defined.
We need them because _set_bit etc are not SMP safe if !CONFIG_SMP. But
under Xen you might be communicating with a completely external entity
who might be on another CPU (e.g. two uniprocessor guests communicating
via event channels and grant tables). So we need a variant of the bit
ops which are SMP safe even on a UP kernel.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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arch/arm/include/asm/sync_bitops.h
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arch/arm/include/asm/sync_bitops.h
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#ifndef __ASM_SYNC_BITOPS_H__
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#define __ASM_SYNC_BITOPS_H__
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#include <asm/bitops.h>
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#include <asm/system.h>
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/* sync_bitops functions are equivalent to the SMP implementation of the
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* original functions, independently from CONFIG_SMP being defined.
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*
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* We need them because _set_bit etc are not SMP safe if !CONFIG_SMP. But
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* under Xen you might be communicating with a completely external entity
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* who might be on another CPU (e.g. two uniprocessor guests communicating
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* via event channels and grant tables). So we need a variant of the bit
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* ops which are SMP safe even on a UP kernel.
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*/
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#define sync_set_bit(nr, p) _set_bit(nr, p)
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#define sync_clear_bit(nr, p) _clear_bit(nr, p)
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#define sync_change_bit(nr, p) _change_bit(nr, p)
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#define sync_test_and_set_bit(nr, p) _test_and_set_bit(nr, p)
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#define sync_test_and_clear_bit(nr, p) _test_and_clear_bit(nr, p)
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#define sync_test_and_change_bit(nr, p) _test_and_change_bit(nr, p)
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#define sync_test_bit(nr, addr) test_bit(nr, addr)
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#define sync_cmpxchg cmpxchg
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#endif