| Message ID | 20201025214842.5924-2-linux@rasmusvillemoes.dk (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | deterministic random testing | expand |
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 <linux@rasmusvillemoes.dk> > --- > 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 <pmladek@suse.com> Well, I guess that we need ack from Willy. Best Regards, Petr
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 */
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 <linux@rasmusvillemoes.dk> --- include/linux/prandom.h | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+)