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| author |   Alan Stern <stern@rowland.harvard.edu> | 2018-02-20 15:25:10 -0800 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2018-02-21 09:58:15 +0100 |
| commit | 556bb7d252ae42d4653557325670e665087c38ad (patch) | |
| tree | e57c5bd41de47f4ff5c19f406f063bda54b163fd /tools/memory-model | |
| parent | tools/memory-model: Add required herd7 version to README file (diff) | |
| download | wireguard-linux-556bb7d252ae42d4653557325670e665087c38ad.tar.xz wireguard-linux-556bb7d252ae42d4653557325670e665087c38ad.zip | |
tools/memory-model: Add a S lock-based external-view litmus test
This commit adds a litmus test in which P0() and P1() form a lock-based S
litmus test, with the addition of P2(), which observes P0()'s and P1()'s
accesses with a full memory barrier but without the lock. This litmus
test asks whether writes carried out by two different processes under the
same lock will be seen in order by a third process not holding that lock.
The answer to this question is "yes" for all architectures supporting
the Linux kernel, but is "no" according to the current version of LKMM.
A patch to LKMM is under development.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akiyks@gmail.com
Cc: boqun.feng@gmail.com
Cc: dhowells@redhat.com
Cc: j.alglave@ucl.ac.uk
Cc: linux-arch@vger.kernel.org
Cc: luc.maranget@inria.fr
Cc: nborisov@suse.com
Cc: npiggin@gmail.com
Cc: parri.andrea@gmail.com
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1519169112-20593-10-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'tools/memory-model')
| -rw-r--r-- | tools/memory-model/litmus-tests/ISA2+pooncelock+pooncelock+pombonce.litmus | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/tools/memory-model/litmus-tests/ISA2+pooncelock+pooncelock+pombonce.litmus b/tools/memory-model/litmus-tests/ISA2+pooncelock+pooncelock+pombonce.litmus new file mode 100644 index 000000000000..7a39a0aaa976 --- /dev/null +++ b/tools/memory-model/litmus-tests/ISA2+pooncelock+pooncelock+pombonce.litmus @@ -0,0 +1,41 @@ +C ISA2+pooncelock+pooncelock+pombonce.litmus + +(* + * Result: Sometimes + * + * This test shows that the ordering provided by a lock-protected S + * litmus test (P0() and P1()) are not visible to external process P2(). + * This is likely to change soon. + *) + +{} + +P0(int *x, int *y, spinlock_t *mylock) +{ + spin_lock(mylock); + WRITE_ONCE(*x, 1); + WRITE_ONCE(*y, 1); + spin_unlock(mylock); +} + +P1(int *y, int *z, spinlock_t *mylock) +{ + int r0; + + spin_lock(mylock); + r0 = READ_ONCE(*y); + WRITE_ONCE(*z, 1); + spin_unlock(mylock); +} + +P2(int *x, int *z) +{ + int r1; + int r2; + + r2 = READ_ONCE(*z); + smp_mb(); + r1 = READ_ONCE(*x); +} + +exists (1:r0=1 /\ 2:r2=1 /\ 2:r1=0) |