It is useful for test modules that make use of random numbers to allow
the exact same series of test cases to be repeated (e.g., after fixing
a bug in the code being tested). For that, the test module needs to
obtain its random numbers from a private state that can be seeded by a
known seed, e.g. given as a module parameter (and using a random seed
when that parameter is not given).
There's a few test modules I'm going to modify to follow that
scheme. As preparation, add a _state variant of the existing
prandom_u32_max(), and for convenience, also add a variant that
produces a value in a given range.
Signed-off-by: Rasmus Villemoes <[email protected]>
---
include/linux/prandom.h | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/include/linux/prandom.h b/include/linux/prandom.h
index aa16e6468f91e79e1f31..58ffcd56c705be34fb98 100644
--- a/include/linux/prandom.h
+++ b/include/linux/prandom.h
@@ -46,6 +46,35 @@ static inline u32 prandom_u32_max(u32 ep_ro)
return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
}
+/**
+ * prandom_u32_max_state - get pseudo-random number in internal [0, hi)
+ *
+ * Like prandom_u32_max, but use the given state structure.
+ * @state: pointer to state structure
+ * @hi: (exclusive) upper bound
+ *
+ * Exception: If @hi == 0, this returns 0.
+ */
+static inline u32 prandom_u32_max_state(struct rnd_state *state, u32 hi)
+{
+ return ((u64)prandom_u32_state(state) * hi) >> 32;
+}
+
+/**
+ * prandom_u32_range_state - get pseudo-random number in internal [lo, hi)
+ *
+ * @state: pointer to state structure
+ * @lo: (inclusive) lower bound
+ * @hi: (exclusive) upper bound
+ *
+ * Exception: If @lo == @hi, this returns @lo. Results are unspecified
+ * for @lo > @hi.
+ */
+static inline u32 prandom_u32_range_state(struct rnd_state *state, u32 lo, u32 hi)
+{
+ return lo + prandom_u32_max_state(state, hi - lo);
+}
+
/*
* Handle minimum values for seeds
*/
--
2.23.0
On Sun 2020-10-25 22:48:39, Rasmus Villemoes wrote:
> It is useful for test modules that make use of random numbers to allow
> the exact same series of test cases to be repeated (e.g., after fixing
> a bug in the code being tested). For that, the test module needs to
> obtain its random numbers from a private state that can be seeded by a
> known seed, e.g. given as a module parameter (and using a random seed
> when that parameter is not given).
>
> There's a few test modules I'm going to modify to follow that
> scheme. As preparation, add a _state variant of the existing
> prandom_u32_max(), and for convenience, also add a variant that
> produces a value in a given range.
>
> Signed-off-by: Rasmus Villemoes <[email protected]>
> ---
> include/linux/prandom.h | 29 +++++++++++++++++++++++++++++
> 1 file changed, 29 insertions(+)
>
> diff --git a/include/linux/prandom.h b/include/linux/prandom.h
> index aa16e6468f91e79e1f31..58ffcd56c705be34fb98 100644
> --- a/include/linux/prandom.h
> +++ b/include/linux/prandom.h
> @@ -46,6 +46,35 @@ static inline u32 prandom_u32_max(u32 ep_ro)
> return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
> }
>
> +/**
> + * prandom_u32_max_state - get pseudo-random number in internal [0, hi)
s/internal/interval/
> + *
> + * Like prandom_u32_max, but use the given state structure.
> + * @state: pointer to state structure
> + * @hi: (exclusive) upper bound
> + *
> + * Exception: If @hi == 0, this returns 0.
> + */
> +static inline u32 prandom_u32_max_state(struct rnd_state *state, u32 hi)
> +{
> + return ((u64)prandom_u32_state(state) * hi) >> 32;
> +}
> +
> +/**
> + * prandom_u32_range_state - get pseudo-random number in internal [lo, hi)
same here
> + *
> + * @state: pointer to state structure
> + * @lo: (inclusive) lower bound
> + * @hi: (exclusive) upper bound
> + *
> + * Exception: If @lo == @hi, this returns @lo. Results are unspecified
> + * for @lo > @hi.
> + */
> +static inline u32 prandom_u32_range_state(struct rnd_state *state, u32 lo, u32 hi)
> +{
> + return lo + prandom_u32_max_state(state, hi - lo);
> +}
With the above typo fixes:
Reviewed-by: Petr Mladek <[email protected]>
Well, I guess that we need ack from Willy.
Best Regards,
Petr