reading the same entropy twice

[Bob O'Neill]

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.

Thanks.
-Bob
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