1// SPDX-License-Identifier: GPL-2.0+
  2//
  3// An earlier version of this file appeared in the companion webpage for
  4// "Frightening small children and disconcerting grown-ups: Concurrency
  5// in the Linux kernel" by Alglave, Maranget, McKenney, Parri, and Stern,
  6// which appeared in ASPLOS 2018.
  7
  8// ONCE
  9READ_ONCE(X) __load{once}(X)
 10WRITE_ONCE(X,V) { __store{once}(X,V); }
 11
 12// Release Acquire and friends
 13smp_store_release(X,V) { __store{release}(*X,V); }
 14smp_load_acquire(X) __load{acquire}(*X)
 15rcu_assign_pointer(X,V) { __store{release}(X,V); }
 16rcu_dereference(X) __load{once}(X)
 17smp_store_mb(X,V) { __store{once}(X,V); __fence{mb}; }
 18
 19// Fences
 20smp_mb() { __fence{mb}; }
 21smp_rmb() { __fence{rmb}; }
 22smp_wmb() { __fence{wmb}; }
 23smp_mb__before_atomic() { __fence{before-atomic}; }
 24smp_mb__after_atomic() { __fence{after-atomic}; }
 25smp_mb__after_spinlock() { __fence{after-spinlock}; }
 26smp_mb__after_unlock_lock() { __fence{after-unlock-lock}; }
 27smp_mb__after_srcu_read_unlock() { __fence{after-srcu-read-unlock}; }
 28barrier() { __fence{barrier}; }
 29
 30// Exchange
 31xchg(X,V)  __xchg{mb}(X,V)
 32xchg_relaxed(X,V) __xchg{once}(X,V)
 33xchg_release(X,V) __xchg{release}(X,V)
 34xchg_acquire(X,V) __xchg{acquire}(X,V)
 35cmpxchg(X,V,W) __cmpxchg{mb}(X,V,W)
 36cmpxchg_relaxed(X,V,W) __cmpxchg{once}(X,V,W)
 37cmpxchg_acquire(X,V,W) __cmpxchg{acquire}(X,V,W)
 38cmpxchg_release(X,V,W) __cmpxchg{release}(X,V,W)
 39
 40// Spinlocks
 41spin_lock(X) { __lock(X); }
 42spin_unlock(X) { __unlock(X); }
 43spin_trylock(X) __trylock(X)
 44spin_is_locked(X) __islocked(X)
 45
 46// RCU
 47rcu_read_lock() { __fence{rcu-lock}; }
 48rcu_read_unlock() { __fence{rcu-unlock}; }
 49synchronize_rcu() { __fence{sync-rcu}; }
 50synchronize_rcu_expedited() { __fence{sync-rcu}; }
 51
 52// SRCU
 53srcu_read_lock(X) __load{srcu-lock}(*X)
 54srcu_read_unlock(X,Y) { __store{srcu-unlock}(*X,Y); }
 55srcu_down_read(X) __load{srcu-lock}(*X)
 56srcu_up_read(X,Y) { __store{srcu-unlock}(*X,Y); }
 57synchronize_srcu(X)  { __srcu{sync-srcu}(X); }
 58synchronize_srcu_expedited(X)  { __srcu{sync-srcu}(X); }
 59
 60// Atomic
 61atomic_read(X) READ_ONCE(*X)
 62atomic_set(X,V) { WRITE_ONCE(*X,V); }
 63atomic_read_acquire(X) smp_load_acquire(X)
 64atomic_set_release(X,V) { smp_store_release(X,V); }
 65
 66atomic_add(V,X) { __atomic_op(X,+,V); }
 67atomic_sub(V,X) { __atomic_op(X,-,V); }
 68atomic_inc(X)   { __atomic_op(X,+,1); }
 69atomic_dec(X)   { __atomic_op(X,-,1); }
 70
 71atomic_add_return(V,X) __atomic_op_return{mb}(X,+,V)
 72atomic_add_return_relaxed(V,X) __atomic_op_return{once}(X,+,V)
 73atomic_add_return_acquire(V,X) __atomic_op_return{acquire}(X,+,V)
 74atomic_add_return_release(V,X) __atomic_op_return{release}(X,+,V)
 75atomic_fetch_add(V,X) __atomic_fetch_op{mb}(X,+,V)
 76atomic_fetch_add_relaxed(V,X) __atomic_fetch_op{once}(X,+,V)
 77atomic_fetch_add_acquire(V,X) __atomic_fetch_op{acquire}(X,+,V)
 78atomic_fetch_add_release(V,X) __atomic_fetch_op{release}(X,+,V)
 79
 80atomic_inc_return(X) __atomic_op_return{mb}(X,+,1)
 81atomic_inc_return_relaxed(X) __atomic_op_return{once}(X,+,1)
 82atomic_inc_return_acquire(X) __atomic_op_return{acquire}(X,+,1)
 83atomic_inc_return_release(X) __atomic_op_return{release}(X,+,1)
 84atomic_fetch_inc(X) __atomic_fetch_op{mb}(X,+,1)
 85atomic_fetch_inc_relaxed(X) __atomic_fetch_op{once}(X,+,1)
 86atomic_fetch_inc_acquire(X) __atomic_fetch_op{acquire}(X,+,1)
 87atomic_fetch_inc_release(X) __atomic_fetch_op{release}(X,+,1)
 88
 89atomic_sub_return(V,X) __atomic_op_return{mb}(X,-,V)
 90atomic_sub_return_relaxed(V,X) __atomic_op_return{once}(X,-,V)
 91atomic_sub_return_acquire(V,X) __atomic_op_return{acquire}(X,-,V)
 92atomic_sub_return_release(V,X) __atomic_op_return{release}(X,-,V)
 93atomic_fetch_sub(V,X) __atomic_fetch_op{mb}(X,-,V)
 94atomic_fetch_sub_relaxed(V,X) __atomic_fetch_op{once}(X,-,V)
 95atomic_fetch_sub_acquire(V,X) __atomic_fetch_op{acquire}(X,-,V)
 96atomic_fetch_sub_release(V,X) __atomic_fetch_op{release}(X,-,V)
 97
 98atomic_dec_return(X) __atomic_op_return{mb}(X,-,1)
 99atomic_dec_return_relaxed(X) __atomic_op_return{once}(X,-,1)
100atomic_dec_return_acquire(X) __atomic_op_return{acquire}(X,-,1)
101atomic_dec_return_release(X) __atomic_op_return{release}(X,-,1)
102atomic_fetch_dec(X) __atomic_fetch_op{mb}(X,-,1)
103atomic_fetch_dec_relaxed(X) __atomic_fetch_op{once}(X,-,1)
104atomic_fetch_dec_acquire(X) __atomic_fetch_op{acquire}(X,-,1)
105atomic_fetch_dec_release(X) __atomic_fetch_op{release}(X,-,1)
106
107atomic_xchg(X,V) __xchg{mb}(X,V)
108atomic_xchg_relaxed(X,V) __xchg{once}(X,V)
109atomic_xchg_release(X,V) __xchg{release}(X,V)
110atomic_xchg_acquire(X,V) __xchg{acquire}(X,V)
111atomic_cmpxchg(X,V,W) __cmpxchg{mb}(X,V,W)
112atomic_cmpxchg_relaxed(X,V,W) __cmpxchg{once}(X,V,W)
113atomic_cmpxchg_acquire(X,V,W) __cmpxchg{acquire}(X,V,W)
114atomic_cmpxchg_release(X,V,W) __cmpxchg{release}(X,V,W)
115
116atomic_sub_and_test(V,X) __atomic_op_return{mb}(X,-,V) == 0
117atomic_dec_and_test(X)  __atomic_op_return{mb}(X,-,1) == 0
118atomic_inc_and_test(X)  __atomic_op_return{mb}(X,+,1) == 0
119atomic_add_negative(V,X) __atomic_op_return{mb}(X,+,V) < 0