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xen/arm: sync_bitops

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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>
This commit is contained in:
Stefano Stabellini 2012-08-08 16:34:01 +00:00
parent 36a67abce2
commit e54d2f6152
1 changed files with 27 additions and 0 deletions
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27
arch/arm/include/asm/sync_bitops.h Normal file
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#ifndef __ASM_SYNC_BITOPS_H__
#define __ASM_SYNC_BITOPS_H__
#include <asm/bitops.h>
#include <asm/system.h>
/* 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.
*/
#define sync_set_bit(nr, p) _set_bit(nr, p)
#define sync_clear_bit(nr, p) _clear_bit(nr, p)
#define sync_change_bit(nr, p) _change_bit(nr, p)
#define sync_test_and_set_bit(nr, p) _test_and_set_bit(nr, p)
#define sync_test_and_clear_bit(nr, p) _test_and_clear_bit(nr, p)
#define sync_test_and_change_bit(nr, p) _test_and_change_bit(nr, p)
#define sync_test_bit(nr, addr) test_bit(nr, addr)
#define sync_cmpxchg cmpxchg
#endif