Re: [PATCH v2 3/4] crypto: qcom-rng - Remove crypto_rng interface

[Dmitry Baryshkov]

On Mon, Jun 08, 2026 at 05:58:47PM +0000, Eric Biggers wrote:
> qcom-rng.c exposes the same hardware through two completely separate
> interfaces, crypto_rng and hwrng.  However, the implementation of this
> is buggy because it permits generation operations from these interfaces
> to run concurrently with each other, accessing the same registers.  That
> is, qcom_rng_generate() synchronizes with itself but not with
> qcom_hwrng_read().  This results in potential repetition of output from
> the RNG, output of non-random values, etc.
> 
> Fortunately, there's actually no point in hardware RNG drivers
> implementing the crypto_rng interface.  It's not actually used by
> anything besides the "rng" algorithm type of AF_ALG, which in turn is
> not actually used in practice.  Other crypto_rng hardware drivers are
> likewise being phased out, leaving just the hwrng support.
> 
> Thus, remove it to simplify the code and avoid conflict (and confusion)
> with the hwrng interface which is the one that actually matters.
> 
> Fixes: f29cd5bb64c2 ("crypto: qcom-rng - Add hw_random interface support")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> ---
>  drivers/crypto/Kconfig    |   1 -
>  drivers/crypto/qcom-rng.c | 158 +++++---------------------------------
>  2 files changed, 19 insertions(+), 140 deletions(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>


-- 
With best wishes
Dmitry