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Subject: Re: [RFC][PATCH 0/2] reworking cause_ipi and adding global doorbell
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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org, Michael Ellerman <mpe@ellerman.id.au>
Date: Tue, 14 Mar 2017 14:57:20 +1100
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On Tue, 2017-03-14 at 12:53 +1000, Nicholas Piggin wrote:
> >   - Load all
> >   - For each byte if set
> >      - clear byte
> >      - then call handler
> 
> Yes. I think that will be okay because we shouldn't get any load-hit-
> store
> issues. I'll do some benchmarking anyway.

We might need a sync still between clearing the byte and calling the
handler no ? Or at least a smp_wmb() to ensure that the clear is
visible before any action of the handler.

Cheers,
Ben.