On Fri, Jun 21, 2024 at 05:02:24PM +0200, Harald Freudenberger wrote:
> When there are rng sources registering at the hwrng core via
> hwrng_register() a struct hwrng is delivered. There is a quality
> field in there which is used to decide which of the registered
> hw rng sources will be used by the hwrng core.
>
> With commit 16bdbae39428 ("hwrng: core - treat default_quality as
> a maximum and default to 1024") there came in a new default of
> 1024 in case this field is empty and all the known hw rng sources
> at that time had been reworked to not fill this field and thus
> use the default of 1024.
>
> The code choosing the 'better' hw rng source during registration
> of a new hw rng source has never been adapted to this and thus
> used 0 if the hw rng implementation does not fill the quality field.
> So when two rng sources register, one with 0 (meaning 1024) and
> the other one with 999, the 999 hw rng will be chosen.
>
> As the later invoked function hwrng_init() anyway adjusts the
> quality field of the hw rng source, this adjustment is now done
> during registration of this new hw rng source.
>
> Tested on s390 with two hardware rng sources: crypto cards and
> trng true random generator device driver.
>
> Fixes: 16bdbae39428 ("hwrng: core - treat default_quality as a maximum and default to 1024")
> Reported-by: Christian Rund <Christian.Rund@xxxxxxxxxx>
> Suggested-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Harald Freudenberger <freude@xxxxxxxxxxxxx>
> ---
> drivers/char/hw_random/core.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
Patch applied. Thanks.
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
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