1// SPDX-License-Identifier: GPL-2.0+
2//
3// An earlier version of this file appears 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 is to appear 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); }
16lockless_dereference(X) __load{lderef}(X)
17rcu_dereference(X) __load{deref}(X)
18
19// Fences
20smp_mb() { __fence{mb} ; }
21smp_rmb() { __fence{rmb} ; }
22smp_wmb() { __fence{wmb} ; }
23smp_read_barrier_depends() { __fence{rb_dep}; }
24smp_mb__before_atomic() { __fence{before-atomic} ; }
25smp_mb__after_atomic() { __fence{after-atomic} ; }
26smp_mb__after_spinlock() { __fence{after-spinlock} ; }
27
28// Exchange
29xchg(X,V)  __xchg{mb}(X,V)
30xchg_relaxed(X,V) __xchg{once}(X,V)
31xchg_release(X,V) __xchg{release}(X,V)
32xchg_acquire(X,V) __xchg{acquire}(X,V)
33cmpxchg(X,V,W) __cmpxchg{mb}(X,V,W)
34cmpxchg_relaxed(X,V,W) __cmpxchg{once}(X,V,W)
35cmpxchg_acquire(X,V,W) __cmpxchg{acquire}(X,V,W)
36cmpxchg_release(X,V,W) __cmpxchg{release}(X,V,W)
37
38// Spinlocks
39spin_lock(X) { __lock(X) ; }
40spin_unlock(X) { __unlock(X) ; }
41spin_trylock(X) __trylock(X)
42
43// RCU
44rcu_read_lock() { __fence{rcu-lock}; }
45rcu_read_unlock() { __fence{rcu-unlock};}
46synchronize_rcu() { __fence{sync-rcu}; }
47synchronize_rcu_expedited() { __fence{sync-rcu}; }
48
49// Atomic
50atomic_read(X) READ_ONCE(*X)
51atomic_set(X,V) { WRITE_ONCE(*X,V) ; }
52atomic_read_acquire(X) smp_load_acquire(X)
53atomic_set_release(X,V) { smp_store_release(X,V); }
54
55atomic_add(V,X) { __atomic_op(X,+,V) ; }
56atomic_sub(V,X) { __atomic_op(X,-,V) ; }
57atomic_inc(X)   { __atomic_op(X,+,1) ; }
58atomic_dec(X)   { __atomic_op(X,-,1) ; }
59
60atomic_add_return(V,X) __atomic_op_return{mb}(X,+,V)
61atomic_add_return_relaxed(V,X) __atomic_op_return{once}(X,+,V)
62atomic_add_return_acquire(V,X) __atomic_op_return{acquire}(X,+,V)
63atomic_add_return_release(V,X) __atomic_op_return{release}(X,+,V)
64atomic_fetch_add(V,X) __atomic_fetch_op{mb}(X,+,V)
65atomic_fetch_add_relaxed(V,X) __atomic_fetch_op{once}(X,+,V)
66atomic_fetch_add_acquire(V,X) __atomic_fetch_op{acquire}(X,+,V)
67atomic_fetch_add_release(V,X) __atomic_fetch_op{release}(X,+,V)
68
69atomic_inc_return(X) __atomic_op_return{mb}(X,+,1)
70atomic_inc_return_relaxed(X) __atomic_op_return{once}(X,+,1)
71atomic_inc_return_acquire(X) __atomic_op_return{acquire}(X,+,1)
72atomic_inc_return_release(X) __atomic_op_return{release}(X,+,1)
73atomic_fetch_inc(X) __atomic_fetch_op{mb}(X,+,1)
74atomic_fetch_inc_relaxed(X) __atomic_fetch_op{once}(X,+,1)
75atomic_fetch_inc_acquire(X) __atomic_fetch_op{acquire}(X,+,1)
76atomic_fetch_inc_release(X) __atomic_fetch_op{release}(X,+,1)
77
78atomic_sub_return(V,X) __atomic_op_return{mb}(X,-,V)
79atomic_sub_return_relaxed(V,X) __atomic_op_return{once}(X,-,V)
80atomic_sub_return_acquire(V,X) __atomic_op_return{acquire}(X,-,V)
81atomic_sub_return_release(V,X) __atomic_op_return{release}(X,-,V)
82atomic_fetch_sub(V,X) __atomic_fetch_op{mb}(X,-,V)
83atomic_fetch_sub_relaxed(V,X) __atomic_fetch_op{once}(X,-,V)
84atomic_fetch_sub_acquire(V,X) __atomic_fetch_op{acquire}(X,-,V)
85atomic_fetch_sub_release(V,X) __atomic_fetch_op{release}(X,-,V)
86
87atomic_dec_return(X) __atomic_op_return{mb}(X,-,1)
88atomic_dec_return_relaxed(X) __atomic_op_return{once}(X,-,1)
89atomic_dec_return_acquire(X) __atomic_op_return{acquire}(X,-,1)
90atomic_dec_return_release(X) __atomic_op_return{release}(X,-,1)
91atomic_fetch_dec(X) __atomic_fetch_op{mb}(X,-,1)
92atomic_fetch_dec_relaxed(X) __atomic_fetch_op{once}(X,-,1)
93atomic_fetch_dec_acquire(X) __atomic_fetch_op{acquire}(X,-,1)
94atomic_fetch_dec_release(X) __atomic_fetch_op{release}(X,-,1)
95
96atomic_xchg(X,V) __xchg{mb}(X,V)
97atomic_xchg_relaxed(X,V) __xchg{once}(X,V)
98atomic_xchg_release(X,V) __xchg{release}(X,V)
99atomic_xchg_acquire(X,V) __xchg{acquire}(X,V)
100atomic_cmpxchg(X,V,W) __cmpxchg{mb}(X,V,W)
101atomic_cmpxchg_relaxed(X,V,W) __cmpxchg{once}(X,V,W)
102atomic_cmpxchg_acquire(X,V,W) __cmpxchg{acquire}(X,V,W)
103atomic_cmpxchg_release(X,V,W) __cmpxchg{release}(X,V,W)
104
105atomic_sub_and_test(V,X) __atomic_op_return{mb}(X,-,V) == 0
106atomic_dec_and_test(X)  __atomic_op_return{mb}(X,-,1) == 0
107atomic_inc_and_test(X)  __atomic_op_return{mb}(X,+,1) == 0
108atomic_add_negative(V,X) __atomic_op_return{mb}(X,+,V) < 0
109