arch/arm/include/asm/sync_bitops.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __ASM_SYNC_BITOPS_H__
   3 #define __ASM_SYNC_BITOPS_H__
   4
   5 #include <asm/bitops.h>
   6
   7 /* sync_bitops functions are equivalent to the SMP implementation of the
   8  * original functions, independently from CONFIG_SMP being defined.
   9  *
  10  * We need them because _set_bit etc are not SMP safe if !CONFIG_SMP. But
  11  * under Xen you might be communicating with a completely external entity
  12  * who might be on another CPU (e.g. two uniprocessor guests communicating
  13  * via event channels and grant tables). So we need a variant of the bit
  14  * ops which are SMP safe even on a UP kernel.
  15  */
  16
  17 /*
  18  * Unordered
  19  */
  20
  21 #define sync_set_bit(nr, p)             _set_bit(nr, p)
  22 #define sync_clear_bit(nr, p)           _clear_bit(nr, p)
  23 #define sync_change_bit(nr, p)          _change_bit(nr, p)
  24 #define sync_test_bit(nr, addr)         test_bit(nr, addr)
  25
  26 /*
  27  * Fully ordered
  28  */
  29
  30 int _sync_test_and_set_bit(int nr, volatile unsigned long * p);
  31 #define sync_test_and_set_bit(nr, p)    _sync_test_and_set_bit(nr, p)
  32
  33 int _sync_test_and_clear_bit(int nr, volatile unsigned long * p);
  34 #define sync_test_and_clear_bit(nr, p)  _sync_test_and_clear_bit(nr, p)
  35
  36 int _sync_test_and_change_bit(int nr, volatile unsigned long * p);
  37 #define sync_test_and_change_bit(nr, p) _sync_test_and_change_bit(nr, p)
  38
  39 #define arch_sync_cmpxchg(ptr, old, new)                                \
  40 ({                                                                      \
  41         __typeof__(*(ptr)) __ret;                                       \
  42         __smp_mb__before_atomic();                                      \
  43         __ret = arch_cmpxchg_relaxed((ptr), (old), (new));              \
  44         __smp_mb__after_atomic();                                       \
  45         __ret;                                                          \
  46 })
  47
  48 #endif