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| author | Stefano Stabellini <stefano.stabellini@eu.citrix.com> | 2012-08-08 16:34:01 +0000 |
|---|---|---|
| committer | Stefano Stabellini <stefano.stabellini@eu.citrix.com> | 2012-08-08 16:34:01 +0000 |
| commit | e54d2f61528165bbe0e5f628b111eab3be31c3b5 (patch) | |
| tree | f8233f60976e66c3e09ee5f2bf76da5d3f3c0477 /arch/arm/include/asm/sync_bitops.h | |
| parent | 36a67abce227af005b4a595735556942b74f6741 (diff) | |
| download | linux-e54d2f61528165bbe0e5f628b111eab3be31c3b5.tar.bz2 | |
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>
Diffstat (limited to 'arch/arm/include/asm/sync_bitops.h')
| -rw-r--r-- | arch/arm/include/asm/sync_bitops.h | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/arch/arm/include/asm/sync_bitops.h b/arch/arm/include/asm/sync_bitops.h new file mode 100644 index 000000000000..63479eecbf76 --- /dev/null +++ b/arch/arm/include/asm/sync_bitops.h @@ -0,0 +1,27 @@ +#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 |