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Date: Tue, 16 Jul 2002 20:00:43 -0700
To: Thunder from the hill <thunder@ngforever.de>
Cc: Elladan <elladan@eskimo.com>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
       Zack Weinberg <zack@codesourcery.com>, linux-kernel@vger.kernel.org
Subject: Re: close return value (was Re: [ANNOUNCE] Ext3 vs Reiserfs benchmarks)
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On Tue, Jul 16, 2002 at 08:54:54PM -0600, Thunder from the hill wrote:
> Hi,
> 
> On Tue, 16 Jul 2002, Elladan wrote:
> > Two threads share the file descriptor table.  
> > 
> >   1. Thread 1 performs close() on a file descriptor.  close fails.
> >   2. Thread 2 performs open().
> > * 3. Thread 1 performs close() again, just to make sure.
> 
> Thread 2 shouldn't be able to reuse a currently open fd. This application 
> design is seriously broken.

No.

Thread 2 doesn't manage the file descriptor table, the kernel does.
Whether the kernel may re-use the descriptor or not depends on whether
the descriptor is closed or not.  The kernel knows, but unless close()
behaves in a defined way, the application does not at this point.  Thus,
step 3 may either be required, forbidden, or undefined.

-J
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