Re: reading the same entropy twice

[Lee Revell]

On Tue, 2005-02-22 at 16:55 -0500, Bob O'Neill wrote:
> Hello.
> 
> I have noticed that it is possible on an SMP box for two processes to
> simultaneously read the same entropy out of /dev/urandom.  This
> doesn't seem right to me.  I was using the entropy value to generate a
> random number to use as a session ID, so occasionally there would be a
> collision on session IDs, causing a login failure as session IDs are
> required to be unique.  This issue does not appear to be related to
> entropy depletion.
> 
> Could you provide me with some insight into why this is the case, if
> it is intentional?  It seems like it could be addressed with a
> spinlock.

Please check the LKML archives, this was debated at length last month
IIRC.  I don't recall whether it ended conclusivelty.

Lee

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