diff options
| -rw-r--r-- | Documentation/atomic_t.txt | 14 | ||||
| -rw-r--r-- | Documentation/litmus-tests/atomic/Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus | 24 | ||||
| -rw-r--r-- | Documentation/litmus-tests/atomic/README | 7 |
3 files changed, 38 insertions, 7 deletions
diff --git a/Documentation/atomic_t.txt b/Documentation/atomic_t.txt index 0ab747e0d5ac..67d1d99f8589 100644 --- a/Documentation/atomic_t.txt +++ b/Documentation/atomic_t.txt @@ -85,21 +85,21 @@ smp_store_release() respectively. Therefore, if you find yourself only using the Non-RMW operations of atomic_t, you do not in fact need atomic_t at all and are doing it wrong. -A subtle detail of atomic_set{}() is that it should be observable to the RMW -ops. That is: +A note for the implementation of atomic_set{}() is that it must not break the +atomicity of the RMW ops. That is: - C atomic-set + C Atomic-RMW-ops-are-atomic-WRT-atomic_set { - atomic_set(v, 1); + atomic_t v = ATOMIC_INIT(1); } - P1(atomic_t *v) + P0(atomic_t *v) { - atomic_add_unless(v, 1, 0); + (void)atomic_add_unless(v, 1, 0); } - P2(atomic_t *v) + P1(atomic_t *v) { atomic_set(v, 0); } diff --git a/Documentation/litmus-tests/atomic/Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus b/Documentation/litmus-tests/atomic/Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus new file mode 100644 index 000000000000..49385314d911 --- /dev/null +++ b/Documentation/litmus-tests/atomic/Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus @@ -0,0 +1,24 @@ +C Atomic-RMW-ops-are-atomic-WRT-atomic_set + +(* + * Result: Never + * + * Test that atomic_set() cannot break the atomicity of atomic RMWs. + *) + +{ + atomic_t v = ATOMIC_INIT(1); +} + +P0(atomic_t *v) +{ + (void)atomic_add_unless(v, 1, 0); +} + +P1(atomic_t *v) +{ + atomic_set(v, 0); +} + +exists +(v=2) diff --git a/Documentation/litmus-tests/atomic/README b/Documentation/litmus-tests/atomic/README index ae61201a4271..a1b72410b539 100644 --- a/Documentation/litmus-tests/atomic/README +++ b/Documentation/litmus-tests/atomic/README @@ -2,3 +2,10 @@ This directory contains litmus tests that are typical to describe the semantics of our atomic APIs. For more information about how to "run" a litmus test or how to generate a kernel test module based on a litmus test, please see tools/memory-model/README. + +============ +LITMUS TESTS +============ + +Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus + Test that atomic_set() cannot break the atomicity of atomic RMWs. |