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linux-next/tools/memory-model/litmus-tests/MP+porevlocks.litmus
Paul E. McKenney 8f32543b61 EXP litmus_tests: Add comments explaining tests' purposes
This commit adds comments to the litmus tests summarizing what these
tests are intended to demonstrate.

[ paulmck: Apply Andrea's and Alan's feedback. ]
Suggested-by: Ingo Molnar <mingo@kernel.org>
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: stern@rowland.harvard.edu
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1519169112-20593-4-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-21 09:58:13 +01:00

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Plaintext

C MP+porevlocks
(*
* Result: Never
*
* This litmus test demonstrates how lock acquisitions and releases can
* stand in for smp_load_acquire() and smp_store_release(), respectively.
* In other words, when holding a given lock (or indeed after releasing a
* given lock), a CPU is not only guaranteed to see the accesses that other
* CPUs made while previously holding that lock, it is also guaranteed to
* see all prior accesses by those other CPUs.
*)
{}
P0(int *x, int *y, spinlock_t *mylock)
{
int r0;
int r1;
r0 = READ_ONCE(*y);
spin_lock(mylock);
r1 = READ_ONCE(*x);
spin_unlock(mylock);
}
P1(int *x, int *y, spinlock_t *mylock)
{
spin_lock(mylock);
WRITE_ONCE(*x, 1);
spin_unlock(mylock);
WRITE_ONCE(*y, 1);
}
exists (0:r0=1 /\ 0:r1=0)