From e30d02355536e9678ab8a4dfcd6e90a86479b10f Mon Sep 17 00:00:00 2001 From: Boqun Feng Date: Thu, 26 Mar 2020 10:40:22 +0800 Subject: Documentation/litmus-tests/atomic: Add a test for smp_mb__after_atomic() We already use a litmus test in atomic_t.txt to describe atomic RMW + smp_mb__after_atomic() is stronger than acquire (both the read and the write parts are ordered). So make it a litmus test in atomic-tests directory, so that people can access the litmus easily. Additionally, change the processor numbers "P1, P2" to "P0, P1" in atomic_t.txt for the consistency with the processor numbers in the litmus test, which herd can handle. Acked-by: Alan Stern Acked-by: Andrea Parri Signed-off-by: Boqun Feng Reviewed-by: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney --- ...b__after_atomic-is-stronger-than-acquire.litmus | 32 ++++++++++++++++++++++ Documentation/litmus-tests/atomic/README | 5 ++++ 2 files changed, 37 insertions(+) create mode 100644 Documentation/litmus-tests/atomic/Atomic-RMW+mb__after_atomic-is-stronger-than-acquire.litmus (limited to 'Documentation/litmus-tests') diff --git a/Documentation/litmus-tests/atomic/Atomic-RMW+mb__after_atomic-is-stronger-than-acquire.litmus b/Documentation/litmus-tests/atomic/Atomic-RMW+mb__after_atomic-is-stronger-than-acquire.litmus new file mode 100644 index 000000000000..9a8e31a44b28 --- /dev/null +++ b/Documentation/litmus-tests/atomic/Atomic-RMW+mb__after_atomic-is-stronger-than-acquire.litmus @@ -0,0 +1,32 @@ +C Atomic-RMW+mb__after_atomic-is-stronger-than-acquire + +(* + * Result: Never + * + * Test that an atomic RMW followed by a smp_mb__after_atomic() is + * stronger than a normal acquire: both the read and write parts of + * the RMW are ordered before the subsequential memory accesses. + *) + +{ +} + +P0(int *x, atomic_t *y) +{ + int r0; + int r1; + + r0 = READ_ONCE(*x); + smp_rmb(); + r1 = atomic_read(y); +} + +P1(int *x, atomic_t *y) +{ + atomic_inc(y); + smp_mb__after_atomic(); + WRITE_ONCE(*x, 1); +} + +exists +(0:r0=1 /\ 0:r1=0) diff --git a/Documentation/litmus-tests/atomic/README b/Documentation/litmus-tests/atomic/README index a1b72410b539..714cf93816ea 100644 --- a/Documentation/litmus-tests/atomic/README +++ b/Documentation/litmus-tests/atomic/README @@ -7,5 +7,10 @@ tools/memory-model/README. LITMUS TESTS ============ +Atomic-RMW+mb__after_atomic-is-stronger-than-acquire + Test that an atomic RMW followed by a smp_mb__after_atomic() is + stronger than a normal acquire: both the read and write parts of + the RMW are ordered before the subsequential memory accesses. + Atomic-RMW-ops-are-atomic-WRT-atomic_set.litmus Test that atomic_set() cannot break the atomicity of atomic RMWs. -- cgit v1.2.3