tools/testing/selftests/futex/include/atomic.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /******************************************************************************
   3  *
   4  *   Copyright © International Business Machines  Corp., 2009
   5  *
   6  * DESCRIPTION
   7  *      GCC atomic builtin wrappers
   8  *      http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
   9  *
  10  * AUTHOR
  11  *      Darren Hart <dvhart@linux.intel.com>
  12  *
  13  * HISTORY
  14  *      2009-Nov-17: Initial version by Darren Hart <dvhart@linux.intel.com>
  15  *
  16  *****************************************************************************/
  17
  18 #ifndef _ATOMIC_H
  19 #define _ATOMIC_H
  20
  21 typedef struct {
  22         volatile int val;
  23 } atomic_t;
  24
  25 #define ATOMIC_INITIALIZER { 0 }
  26
  27 /**
  28  * atomic_cmpxchg() - Atomic compare and exchange
  29  * @uaddr:      The address of the futex to be modified
  30  * @oldval:     The expected value of the futex
  31  * @newval:     The new value to try and assign the futex
  32  *
  33  * Return the old value of addr->val.
  34  */
  35 static inline int
  36 atomic_cmpxchg(atomic_t *addr, int oldval, int newval)
  37 {
  38         return __sync_val_compare_and_swap(&addr->val, oldval, newval);
  39 }
  40
  41 /**
  42  * atomic_inc() - Atomic incrememnt
  43  * @addr:       Address of the variable to increment
  44  *
  45  * Return the new value of addr->val.
  46  */
  47 static inline int
  48 atomic_inc(atomic_t *addr)
  49 {
  50         return __sync_add_and_fetch(&addr->val, 1);
  51 }
  52
  53 /**
  54  * atomic_dec() - Atomic decrement
  55  * @addr:       Address of the variable to decrement
  56  *
  57  * Return the new value of addr-val.
  58  */
  59 static inline int
  60 atomic_dec(atomic_t *addr)
  61 {
  62         return __sync_sub_and_fetch(&addr->val, 1);
  63 }
  64
  65 /**
  66  * atomic_set() - Atomic set
  67  * @addr:       Address of the variable to set
  68  * @newval:     New value for the atomic_t
  69  *
  70  * Return the new value of addr->val.
  71  */
  72 static inline int
  73 atomic_set(atomic_t *addr, int newval)
  74 {
  75         addr->val = newval;
  76         return newval;
  77 }
  78
  79 #endif