Re: [Xen-devel] [PATCH 2/3] blktap: mb fixes

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 7/11/06 12:19, "Isaku Yamahata" <yamahata@xxxxxxxxxxxxx> wrote:

> Hmm.. since you don't believe any race, then please revert
> this mb patch except NULL check chunk.
> I certainly observed that tapdisk failed to get new request on IA64.
> If it is really caused by the race, I will sent a patch again.
> (or I'll sent another patch which fixes another issues)

I agreed the other barriers were needed, just not that one. If it were
required, we'd have the same race in blkback.c.

> BTW,
> why is wmb() in write_rsp_to_ring() of tools/blktap/drivers/tapdisk.c
> necessary?
> RING_PUSH_RESPONSES() of kick_responses() issues wmb() so that
> wmb() in write_rsp_to_ring() isn't needed, I think.

I agree. I'll remove it.

 -- Keir



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