Re: [PATCH] [8/18] BKL-removal: Remove BKL from remote_llseek

From: Andi Kleen
Date: Sun Jan 27 2008 - 23:38:43 EST


On Monday 28 January 2008 05:13:09 Trond Myklebust wrote:
>
> On Mon, 2008-01-28 at 03:58 +0100, Andi Kleen wrote:
> > The problem is that it's not a race in who gets to do its thing first, but a
> > parallel reader can actually see a corrupted value from the two independent
> > words on 32bit (e.g. during a 4GB). And this could actually completely corrupt
> > f_pos when it happens with two racing relative seeks or read/write()s
> >
> > I would consider that a bug.
>
> I disagree. The corruption occurs because this isn't a situation that is
> allowed by either POSIX or SUSv2/v3. Exactly what spec are you referring
> to here?

No specific spec, just general quality of implementation. We normally don't have
non thread safe system calls even if it was in theory allowed by some specification.

-Andi
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