1 ============ 1 ============
2 LITMUS TESTS 2 LITMUS TESTS
3 ============ 3 ============
4 4
5 Each subdirectory contains litmus tests that a 5 Each subdirectory contains litmus tests that are typical to describe the
6 semantics of respective kernel APIs. 6 semantics of respective kernel APIs.
7 For more information about how to "run" a litm 7 For more information about how to "run" a litmus test or how to generate
8 a kernel test module based on a litmus test, p 8 a kernel test module based on a litmus test, please see
9 tools/memory-model/README. 9 tools/memory-model/README.
10 10
11 11
12 atomic (/atomic directory) 12 atomic (/atomic directory)
13 -------------------------- 13 --------------------------
14 14
15 Atomic-RMW+mb__after_atomic-is-stronger-than-a 15 Atomic-RMW+mb__after_atomic-is-stronger-than-acquire.litmus
16 Test that an atomic RMW followed by a smp_ 16 Test that an atomic RMW followed by a smp_mb__after_atomic() is
17 stronger than a normal acquire: both the r 17 stronger than a normal acquire: both the read and write parts of
18 the RMW are ordered before the subsequenti 18 the RMW are ordered before the subsequential memory accesses.
19 19
20 Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmu 20 Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus
21 Test that atomic_set() cannot break the at 21 Test that atomic_set() cannot break the atomicity of atomic RMWs.
22 NOTE: Require herd7 7.56 or later which su 22 NOTE: Require herd7 7.56 or later which supports "(void)expr".
23 23
24 cmpxchg-fail-ordered-1.litmus <<
25 Demonstrate that a failing cmpxchg() opera <<
26 when followed by smp_mb__after_atomic(). <<
27 <<
28 cmpxchg-fail-ordered-2.litmus <<
29 Demonstrate that a failing cmpxchg() opera <<
30 operation when followed by smp_mb__after_a <<
31 <<
32 cmpxchg-fail-unordered-1.litmus <<
33 Demonstrate that a failing cmpxchg() opera <<
34 full barrier. <<
35 <<
36 cmpxchg-fail-unordered-2.litmus <<
37 Demonstrate that a failing cmpxchg() opera <<
38 acquire operation. <<
39 <<
40 <<
41 locking (/locking directory) <<
42 ---------------------------- <<
43 <<
44 DCL-broken.litmus <<
45 Demonstrates that double-checked locking n <<
46 the obvious lock acquisitions and releases <<
47 <<
48 DCL-fixed.litmus <<
49 Demonstrates corrected double-checked lock <<
50 smp_store_release() and smp_load_acquire() <<
51 obvious lock acquisitions and releases. <<
52 <<
53 RM-broken.litmus <<
54 Demonstrates problems with "roach motel" l <<
55 freely moved into lock-based critical sect <<
56 shows how to use the "filter" clause to di <<
57 would be excluded by other code not modele <<
58 Note also that this "roach motel" optimiza <<
59 physically moving P1()'s two reads from x <<
60 <<
61 What is a roach motel? This is from an ol <<
62 a cockroach trap, much later featured in o <<
63 Black" movies. "The roaches check in. Th <<
64 <<
65 RM-fixed.litmus <<
66 The counterpart to RM-broken.litmus, showi <<
67 x safely outside of the critical section. <<
68 <<
69 24
70 RCU (/rcu directory) 25 RCU (/rcu directory)
71 -------------------- 26 --------------------
72 27
73 MP+onceassign+derefonce.litmus (under tools/me 28 MP+onceassign+derefonce.litmus (under tools/memory-model/litmus-tests/)
74 Demonstrates the use of rcu_assign_pointer 29 Demonstrates the use of rcu_assign_pointer() and rcu_dereference() to
75 ensure that an RCU reader will not see pre 30 ensure that an RCU reader will not see pre-initialization garbage.
76 31
77 RCU+sync+read.litmus 32 RCU+sync+read.litmus
78 RCU+sync+free.litmus 33 RCU+sync+free.litmus
79 Both the above litmus tests demonstrate th 34 Both the above litmus tests demonstrate the RCU grace period guarantee
80 that an RCU read-side critical section can 35 that an RCU read-side critical section can never span a grace period.
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