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e30d023555
We already use a litmus test in atomic_t.txt to describe atomic RMW + smp_mb__after_atomic() is stronger than acquire (both the read and the write parts are ordered). So make it a litmus test in atomic-tests directory, so that people can access the litmus easily. Additionally, change the processor numbers "P1, P2" to "P0, P1" in atomic_t.txt for the consistency with the processor numbers in the litmus test, which herd can handle. Acked-by: Alan Stern <stern@rowland.harvard.edu> Acked-by: Andrea Parri <parri.andrea@gmail.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
32 lines
508 B
Text
32 lines
508 B
Text
C Atomic-RMW+mb__after_atomic-is-stronger-than-acquire
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(*
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* Result: Never
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*
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* Test that an atomic RMW followed by a smp_mb__after_atomic() is
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* stronger than a normal acquire: both the read and write parts of
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* the RMW are ordered before the subsequential memory accesses.
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*)
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{
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}
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P0(int *x, atomic_t *y)
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{
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int r0;
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int r1;
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r0 = READ_ONCE(*x);
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smp_rmb();
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r1 = atomic_read(y);
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}
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P1(int *x, atomic_t *y)
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{
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atomic_inc(y);
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smp_mb__after_atomic();
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WRITE_ONCE(*x, 1);
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}
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exists
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(0:r0=1 /\ 0:r1=0)
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