[PATCH] Add PRIV_TOPREQ for per "top request" / req->top state

[Poul-Henning Kamp]

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In message <54FF7412.80704 at schokola.de>, Nils Goroll writes:
>On 10/03/15 22:02, Poul-Henning Kamp wrote:
>> So how does locking of a PRIV_TOPREQ work if we implement parallel-ESI ?
>> 
>> We might have two different child-fetches running in parallel, asking for
>> a PRIV_TOPREQ at the exact same instant from the same VMOD ?
>
>I tend towards 'point out to the requirement once we get parallel ESI (if ever)
>and leave it up to the vmod'

I'm not talking about the vmod, I'm talking about the core code which
provides the PRIV variable.

And yes, it's not an issue right now, but I like to make sure we don't
paint ourselves into corners when we can avoid it, so I think it is
a worthwhile exercise to think about it.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.