tree 97c4a18e6a60024256fc92fffed0cae95d0b4ef7
parent bfa76d49576599a4b9f9b7a71f23d73d6dcff735
author George Spelvin <linux@horizon.com> 1423287126 -0500
committer Linus Torvalds <torvalds@linux-foundation.org> 1423513722 -0800

random: Fix fast_mix() function

There was a bad typo in commit 43759d4f429c ("random: use an improved
fast_mix() function") and I didn't notice because it "looked right", so
I saw what I expected to see when I reviewed it.

Only months later did I look and notice it's not the Threefish-inspired
mix function that I had designed and optimized.

Mea Culpa.  Each input bit still has a chance to affect each output bit,
and the fast pool is spilled *long* before it fills, so it's not a total
disaster, but it's definitely not the intended great improvement.

I'm still working on finding better rotation constants.  These are good
enough, but since it's unrolled twice, it's possible to get better
mixing for free by using eight different constants rather than repeating
the same four.

Signed-off-by: George Spelvin <linux@horizon.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org  # v3.16+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>