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

[Andrew Morton]

On Mon, 28 Jan 2008 05:38:25 +0100 Andi Kleen <ak@xxxxxxx> wrote:

> 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.

I completely agree.  If one thread writes A and another writes B then the
kernel should record either A or B, not ((A & 0xffffffff00000000) | (B &
0xffffffff))
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/