2021-05-27 00:09:36 +05:00
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C MP+fencewmbonceonce+fencermbonceonce
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(*
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* Result: Never
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*
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* This litmus test demonstrates that smp_wmb() and smp_rmb() provide
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* sufficient ordering for the message-passing pattern. However, it
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* is usually better to use smp_store_release() and smp_load_acquire().
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*)
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{}
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2021-10-02 21:09:28 +05:00
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P0(int *buf, int *flag) // Producer
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2021-05-27 00:09:36 +05:00
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{
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2021-10-02 21:09:28 +05:00
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WRITE_ONCE(*buf, 1);
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2021-05-27 00:09:36 +05:00
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smp_wmb();
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2021-10-02 21:09:28 +05:00
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WRITE_ONCE(*flag, 1);
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2021-05-27 00:09:36 +05:00
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}
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2021-10-02 21:09:28 +05:00
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P1(int *buf, int *flag) // Consumer
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2021-05-27 00:09:36 +05:00
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{
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int r0;
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int r1;
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2021-10-02 21:09:28 +05:00
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r0 = READ_ONCE(*flag);
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2021-05-27 00:09:36 +05:00
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smp_rmb();
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2021-10-02 21:09:28 +05:00
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r1 = READ_ONCE(*buf);
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2021-05-27 00:09:36 +05:00
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}
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2021-10-02 21:09:28 +05:00
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exists (1:r0=1 /\ 1:r1=0) (* Bad outcome. *)
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