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author | Ingo Molnar <mingo@kernel.org> | 2018-04-05 09:20:34 +0200 |
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committer | Ingo Molnar <mingo@kernel.org> | 2018-04-05 09:20:34 +0200 |
commit | ea2a6af517714c52a1209795a03e863e96b460bb (patch) | |
tree | 3bd443bc9b23ceeaf3743eaf2d6d35ec63c620c9 /tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+mbonceonce.litmus | |
parent | 1b5d43cfb69759d8ef8d30469cea31d0c037aed5 (diff) | |
parent | 642e7fd23353e22290e3d51719fcb658dc252342 (diff) | |
download | talos-obmc-linux-ea2a6af517714c52a1209795a03e863e96b460bb.tar.gz talos-obmc-linux-ea2a6af517714c52a1209795a03e863e96b460bb.zip |
Merge branch 'linus' into sched/urgent, to pick up fixes and updates
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+mbonceonce.litmus')
-rw-r--r-- | tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+mbonceonce.litmus | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+mbonceonce.litmus b/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+mbonceonce.litmus new file mode 100644 index 000000000000..a20fc3fafb53 --- /dev/null +++ b/tools/memory-model/litmus-tests/Z6.0+pooncerelease+poacquirerelease+mbonceonce.litmus @@ -0,0 +1,42 @@ +C Z6.0+pooncerelease+poacquirerelease+mbonceonce + +(* + * 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) |