From 76cb841cb886eef6b3bee341a2266c76578724ad Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Mon, 6 May 2024 03:02:30 +0200 Subject: Adding upstream version 4.19.249. Signed-off-by: Daniel Baumann --- ...release+poacquirerelease+fencembonceonce.litmus | 42 ++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus (limited to 'tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus') diff --git a/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus b/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus new file mode 100644 index 000000000..88e70b87a --- /dev/null +++ b/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+fencembonceonce.litmus @@ -0,0 +1,42 @@ +C Z6.0+pooncerelease+poacquirerelease+fencembonceonce + +(* + * Result: Sometimes + * + * This litmus test shows that a release-acquire chain, while sufficient + * when there is but one non-reads-from (AKA non-rf) link, does not suffice + * if there is more than one. Of the three processes, only P1() reads from + * P0's write, which means that there are two non-rf links: P1() to P2() + * is a write-to-write link (AKA a "coherence" or just "co" link) and P2() + * to P0() is a read-to-write link (AKA a "from-reads" or just "fr" link). + * When there are two or more non-rf links, you typically will need one + * full barrier for each non-rf link. (Exceptions include some cases + * involving locking.) + *) + +{} + +P0(int *x, int *y) +{ + WRITE_ONCE(*x, 1); + smp_store_release(y, 1); +} + +P1(int *y, int *z) +{ + int r0; + + r0 = smp_load_acquire(y); + smp_store_release(z, 1); +} + +P2(int *x, int *z) +{ + int r1; + + WRITE_ONCE(*z, 2); + smp_mb(); + r1 = READ_ONCE(*x); +} + +exists (1:r0=1 /\ z=2 /\ 2:r1=0) -- cgit v1.2.3