Re: FastPathStrongRelationLocks still has an issue in HEAD

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Andres Freund <andres(at)2ndquadrant(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: FastPathStrongRelationLocks still has an issue in HEAD
Date: 2014-04-07 14:45:51
Message-ID: CA+TgmoZ9GLoOQugqhF=x_H7U9h_yYi1J649DNgswvfqyW+Zr_A@mail.gmail.com
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On Mon, Apr 7, 2014 at 10:20 AM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> On 2014-04-07 10:06:07 -0400, Robert Haas wrote:
>> I'm a bit suspicious of the patches to
>> static-ify stuff, since that might cause the compiler to think it
>> could move things across function calls that it hadn't thought
>> move-able before, but FastPathStrongLocks references would seem to be
>> the obvious candidate for that, and volatile-izing it ought to have
>> fixed it. I would think.
>
> Hm. It generally might be interesting to get a few !X86 buildfarms
> running builds with LTO enabled. That might expose some dangerous
> assumptions more easily.

I strongly suspect that will break stuff all over the place. We can
either get compiler barriers working for real, or we can start
volatile-izing every reference in an LWLock-protected critical
section. Hint: the second one is insane.

That might be off-topic for this issue at hand, though...

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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