This patch adds a separate pool for use with /dev/urandom.  This prevents a
/dev/urandom read from being able to completely drain the entropy in the
/dev/random pool, and also makes it much more difficult for an attacker to
carry out a state extension attack.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>