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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>
40 lines
658 B
Text
40 lines
658 B
Text
C Z6.0+pooncelock+pooncelock+pombonce
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(*
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* Result: Sometimes
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*
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* This example demonstrates that a pair of accesses made by different
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* processes each while holding a given lock will not necessarily be
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* seen as ordered by a third process not holding that lock.
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*)
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{}
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P0(int *x, int *y, spinlock_t *mylock)
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{
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spin_lock(mylock);
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WRITE_ONCE(*x, 1);
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WRITE_ONCE(*y, 1);
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spin_unlock(mylock);
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}
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P1(int *y, int *z, spinlock_t *mylock)
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{
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int r0;
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spin_lock(mylock);
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r0 = READ_ONCE(*y);
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WRITE_ONCE(*z, 1);
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spin_unlock(mylock);
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}
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P2(int *x, int *z)
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{
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int r1;
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WRITE_ONCE(*z, 2);
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smp_mb();
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r1 = READ_ONCE(*x);
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}
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exists (1:r0=1 /\ z=2 /\ 2:r1=0)
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