On Wed, Mar 11, 2026 at 08:03:58AM +0100, Christoph Hellwig wrote:
> Factor out the guts of __get_random_u32_below into a new helper,
> so that callers with their own prng state can reuse this code.
>
> Signed-off-by: Christoph Hellwig <[email protected]>
I think I'd prefer that the test just uses the mod operation instead,
like many of the existing tests do:
prandom_u32_state(&rng) % ceil
Yes, when ceil isn't a power of 2 the result isn't uniformly
distributed. But that's perfectly fine for these tests, especially with
the values of ceil being used being far smaller than U32_MAX.
There's been an effort to keep the cryptographic random number generator
(drivers/char/random.c and include/linux/random.h) separate from the
non-cryptographic random number generator (lib/random32.c and
include/linux/prandom.h). This patch feels like it's going in a
slightly wrong direction, where random.c gains a function that's used
with both cryptographic and non-cryptographic random numbers.
And if someone actually needs a fully unform distribution, then they'd
probably want cryptographic random numbers as well.
So I'm not sure the proposed combination of "fully uniform
non-cryptographic random numbers" makes much sense.
Plus the '% ceil' implementation is much easier to understand.
- Eric
