Re: [PATCH] random: mix hwgenerator randomness before sleeping

From: Dominik Brodowski
Date: Tue May 03 2022 - 15:56:34 EST


Am Tue, May 03, 2022 at 09:51:41PM +0200 schrieb Jason A. Donenfeld:
> The add_hwgenerator_randomness() function is called in a loop from a
> kthread by the hwgenerator core. It's supposed to sleep when there's
> nothing to do, and wake up periodically for more entropy. Right now it
> receives entropy, sleeps, and then mixes it in. This commit reverses the
> order, so that it always mixes in entropy sooner and sleeps after. This
> way the entropy is more fresh.

... however, the hwgenerator may take quite some time to accumulate entropy
after wakeup. So now we might have a delay between a wakeup ("we need more
entropy!") and that entropy becoming available. Beforehand, the thread only
went to sleep when there is no current need for "fresh" entropy.

Thanks,
Dominik