xref: /linux/tools/memory-model/linux-kernel.def (revision 2da68a77) 
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}; }
27barrier() { __fence{barrier}; }
28
29// Exchange
30xchg(X,V)  __xchg{mb}(X,V)
31xchg_relaxed(X,V) __xchg{once}(X,V)
32xchg_release(X,V) __xchg{release}(X,V)
33xchg_acquire(X,V) __xchg{acquire}(X,V)
34cmpxchg(X,V,W) __cmpxchg{mb}(X,V,W)
35cmpxchg_relaxed(X,V,W) __cmpxchg{once}(X,V,W)
36cmpxchg_acquire(X,V,W) __cmpxchg{acquire}(X,V,W)
37cmpxchg_release(X,V,W) __cmpxchg{release}(X,V,W)
38
39// Spinlocks
40spin_lock(X) { __lock(X); }
41spin_unlock(X) { __unlock(X); }
42spin_trylock(X) __trylock(X)
43spin_is_locked(X) __islocked(X)
44
45// RCU
46rcu_read_lock() { __fence{rcu-lock}; }
47rcu_read_unlock() { __fence{rcu-unlock}; }
48synchronize_rcu() { __fence{sync-rcu}; }
49synchronize_rcu_expedited() { __fence{sync-rcu}; }
50
51// SRCU
52srcu_read_lock(X)  __srcu{srcu-lock}(X)
53srcu_read_unlock(X,Y) { __srcu{srcu-unlock}(X,Y); }
54synchronize_srcu(X)  { __srcu{sync-srcu}(X); }
55synchronize_srcu_expedited(X)  { __srcu{sync-srcu}(X); }
56
57// Atomic
58atomic_read(X) READ_ONCE(*X)
59atomic_set(X,V) { WRITE_ONCE(*X,V); }
60atomic_read_acquire(X) smp_load_acquire(X)
61atomic_set_release(X,V) { smp_store_release(X,V); }
62
63atomic_add(V,X) { __atomic_op(X,+,V); }
64atomic_sub(V,X) { __atomic_op(X,-,V); }
65atomic_inc(X)   { __atomic_op(X,+,1); }
66atomic_dec(X)   { __atomic_op(X,-,1); }
67
68atomic_add_return(V,X) __atomic_op_return{mb}(X,+,V)
69atomic_add_return_relaxed(V,X) __atomic_op_return{once}(X,+,V)
70atomic_add_return_acquire(V,X) __atomic_op_return{acquire}(X,+,V)
71atomic_add_return_release(V,X) __atomic_op_return{release}(X,+,V)
72atomic_fetch_add(V,X) __atomic_fetch_op{mb}(X,+,V)
73atomic_fetch_add_relaxed(V,X) __atomic_fetch_op{once}(X,+,V)
74atomic_fetch_add_acquire(V,X) __atomic_fetch_op{acquire}(X,+,V)
75atomic_fetch_add_release(V,X) __atomic_fetch_op{release}(X,+,V)
76
77atomic_inc_return(X) __atomic_op_return{mb}(X,+,1)
78atomic_inc_return_relaxed(X) __atomic_op_return{once}(X,+,1)
79atomic_inc_return_acquire(X) __atomic_op_return{acquire}(X,+,1)
80atomic_inc_return_release(X) __atomic_op_return{release}(X,+,1)
81atomic_fetch_inc(X) __atomic_fetch_op{mb}(X,+,1)
82atomic_fetch_inc_relaxed(X) __atomic_fetch_op{once}(X,+,1)
83atomic_fetch_inc_acquire(X) __atomic_fetch_op{acquire}(X,+,1)
84atomic_fetch_inc_release(X) __atomic_fetch_op{release}(X,+,1)
85
86atomic_sub_return(V,X) __atomic_op_return{mb}(X,-,V)
87atomic_sub_return_relaxed(V,X) __atomic_op_return{once}(X,-,V)
88atomic_sub_return_acquire(V,X) __atomic_op_return{acquire}(X,-,V)
89atomic_sub_return_release(V,X) __atomic_op_return{release}(X,-,V)
90atomic_fetch_sub(V,X) __atomic_fetch_op{mb}(X,-,V)
91atomic_fetch_sub_relaxed(V,X) __atomic_fetch_op{once}(X,-,V)
92atomic_fetch_sub_acquire(V,X) __atomic_fetch_op{acquire}(X,-,V)
93atomic_fetch_sub_release(V,X) __atomic_fetch_op{release}(X,-,V)
94
95atomic_dec_return(X) __atomic_op_return{mb}(X,-,1)
96atomic_dec_return_relaxed(X) __atomic_op_return{once}(X,-,1)
97atomic_dec_return_acquire(X) __atomic_op_return{acquire}(X,-,1)
98atomic_dec_return_release(X) __atomic_op_return{release}(X,-,1)
99atomic_fetch_dec(X) __atomic_fetch_op{mb}(X,-,1)
100atomic_fetch_dec_relaxed(X) __atomic_fetch_op{once}(X,-,1)
101atomic_fetch_dec_acquire(X) __atomic_fetch_op{acquire}(X,-,1)
102atomic_fetch_dec_release(X) __atomic_fetch_op{release}(X,-,1)
103
104atomic_xchg(X,V) __xchg{mb}(X,V)
105atomic_xchg_relaxed(X,V) __xchg{once}(X,V)
106atomic_xchg_release(X,V) __xchg{release}(X,V)
107atomic_xchg_acquire(X,V) __xchg{acquire}(X,V)
108atomic_cmpxchg(X,V,W) __cmpxchg{mb}(X,V,W)
109atomic_cmpxchg_relaxed(X,V,W) __cmpxchg{once}(X,V,W)
110atomic_cmpxchg_acquire(X,V,W) __cmpxchg{acquire}(X,V,W)
111atomic_cmpxchg_release(X,V,W) __cmpxchg{release}(X,V,W)
112
113atomic_sub_and_test(V,X) __atomic_op_return{mb}(X,-,V) == 0
114atomic_dec_and_test(X)  __atomic_op_return{mb}(X,-,1) == 0
115atomic_inc_and_test(X)  __atomic_op_return{mb}(X,+,1) == 0
116atomic_add_negative(V,X) __atomic_op_return{mb}(X,+,V) < 0
117