On Wed, Jul 02, 2014 at 03:58:15PM +0530, Amit Shah wrote:
> Commit d9e7972619334 "hwrng: add randomness to system from rng sources"
> added a call to rng_get_data() from the hwrng_register() function.
> However, some rng devices need initialization before data can be read
> from them.
>
> Also, the virtio-rng device does not behave properly when this call is
> made in its probe() routine - the virtio core sets the DRIVER_OK status
> bit only on a successful probe, which means the host ignores all
> communication from the guest, and the guest insmod or boot process just
> sits there doing nothing.
>
> This commit makes the call to rng_get_data() depend on no init fn
> pointer being registered by the device. If an init function is
> registered, this call isn't made.
>
> CC: Kees Cook <keescook@xxxxxxxxxxxx>
> CC: Jason Cooper <jason@xxxxxxxxxxxxxx>
> CC: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> CC: <stable@xxxxxxxxxxxxxxx> # For 3.15 only
# v3.15+ should be fine here.
> Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx>
> ---
> drivers/char/hw_random/core.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
> index 334601c..3f3941d 100644
> --- a/drivers/char/hw_random/core.c
> +++ b/drivers/char/hw_random/core.c
> @@ -347,9 +347,11 @@ int hwrng_register(struct hwrng *rng)
> INIT_LIST_HEAD(&rng->list);
> list_add_tail(&rng->list, &rng_list);
>
> - bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1);
> - if (bytes_read > 0)
> - add_device_randomness(bytes, bytes_read);
> + if (!rng->init) {
> + bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1);
> + if (bytes_read > 0)
> + add_device_randomness(bytes, bytes_read);
> + }
afaict, this is redundant at initialization time. current_rng shouldn't
be set yet, so hwrng_init(rng) will get called at line 333. Or, am I
missing something?
thx,
Jason.
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