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Diffstat (limited to 'arch/arm/include/asm/sync_bitops.h')
| -rw-r--r-- | arch/arm/include/asm/sync_bitops.h | 48 |
1 files changed, 48 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 000000000..f46b3c570 --- /dev/null +++ b/arch/arm/include/asm/sync_bitops.h @@ -0,0 +1,48 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_SYNC_BITOPS_H__ +#define __ASM_SYNC_BITOPS_H__ + +#include <asm/bitops.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. + */ + +/* + * Unordered + */ + +#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_bit(nr, addr) test_bit(nr, addr) + +/* + * Fully ordered + */ + +int _sync_test_and_set_bit(int nr, volatile unsigned long * p); +#define sync_test_and_set_bit(nr, p) _sync_test_and_set_bit(nr, p) + +int _sync_test_and_clear_bit(int nr, volatile unsigned long * p); +#define sync_test_and_clear_bit(nr, p) _sync_test_and_clear_bit(nr, p) + +int _sync_test_and_change_bit(int nr, volatile unsigned long * p); +#define sync_test_and_change_bit(nr, p) _sync_test_and_change_bit(nr, p) + +#define arch_sync_cmpxchg(ptr, old, new) \ +({ \ + __typeof__(*(ptr)) __ret; \ + __smp_mb__before_atomic(); \ + __ret = arch_cmpxchg_relaxed((ptr), (old), (new)); \ + __smp_mb__after_atomic(); \ + __ret; \ +}) + +#endif |