Messages in this thread | | | Date | Mon, 14 Jul 2014 08:37:00 -0400 | From | Jason Cooper <> | Subject | Re: [RFC PATCH 1/3] hw_random: allow RNG devices to give early randomness after a delay |
| |
On Mon, Jul 14, 2014 at 10:05:19AM +0530, Amit Shah wrote: > Some RNG devices may not be ready to give early randomness at probe() > time, and hence lose out on the opportunity to contribute to system > randomness at boot- or device hotplug- time. > > This commit schedules a delayed work item for such devices, and fetches > early randomness after a delay. Currently the delay is 500ms, which is > enough for the lone device that needs such treatment: virtio-rng. > > CC: Kees Cook <keescook@chromium.org> > CC: Jason Cooper <jason@lakedaemon.net> > CC: Herbert Xu <herbert@gondor.apana.org.au> > Signed-off-by: Amit Shah <amit.shah@redhat.com> > --- > drivers/char/hw_random/core.c | 20 +++++++++++++++++++- > include/linux/hw_random.h | 8 ++++++++ > 2 files changed, 27 insertions(+), 1 deletion(-) > > diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c > index c4419ea..2a765fd 100644 > --- a/drivers/char/hw_random/core.c > +++ b/drivers/char/hw_random/core.c > @@ -63,7 +63,7 @@ static size_t rng_buffer_size(void) > return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES; > } > > -static void add_early_randomness(struct hwrng *rng) > +static void get_early_randomness(struct hwrng *rng) > { > unsigned char bytes[16]; > int bytes_read; > @@ -79,6 +79,21 @@ static void add_early_randomness(struct hwrng *rng) > add_device_randomness(bytes, bytes_read); > } > > +static void sched_init_random(struct work_struct *work) > +{ > + struct hwrng *rng = container_of(work, struct hwrng, dwork.work); > + > + get_early_randomness(rng); > +} > + > +static void add_early_randomness(struct hwrng *rng)
The add/get naming seems awkward in the above hunks.
> +{ > + if (!(rng->flags & HWRNG_DELAY_READ_AT_INIT)) > + return get_early_randomness(rng); > + > + schedule_delayed_work(&rng->dwork, msecs_to_jiffies(500)); > +} > +
Perhaps instead of rng->flags and a hardcoded delay, we could have rng->seed_delay = msecs_to_jiffies(500) in virtio-rng? Then you can just call unconditionally:
schedule_delayed_work(&rng->dwork, rng->seed_delay);
I think that would be a more extensible solution should other drivers show up with the same issue.
thx,
Jason.
| |