From: Stephan Mueller Subject: Re: [PATCH] crypto: sun4i-ss: support the Security System PRNG Date: Tue, 18 Oct 2016 16:24:22 +0200 Message-ID: <1722218.eZlGktOxfL@tauon.atsec.com> References: <1476794067-28563-1-git-send-email-clabbe.montjoie@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: herbert@gondor.apana.org.au, davem@davemloft.net, maxime.ripard@free-electrons.com, wens@csie.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org To: Corentin Labbe Return-path: Received: from mail.eperm.de ([89.247.134.16]:53648 "EHLO mail.eperm.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758891AbcJROY3 (ORCPT ); Tue, 18 Oct 2016 10:24:29 -0400 In-Reply-To: <1476794067-28563-1-git-send-email-clabbe.montjoie@gmail.com> Sender: linux-crypto-owner@vger.kernel.org List-ID: Am Dienstag, 18. Oktober 2016, 14:34:27 CEST schrieb Corentin Labbe: Hi Corentin, > diff --git a/drivers/crypto/sunxi-ss/sun4i-ss-hwrng.c > b/drivers/crypto/sunxi-ss/sun4i-ss-hwrng.c new file mode 100644 > index 0000000..95fadb7 > --- /dev/null > +++ b/drivers/crypto/sunxi-ss/sun4i-ss-hwrng.c > @@ -0,0 +1,70 @@ > +#include "sun4i-ss.h" > + > +static int sun4i_ss_hwrng_init(struct hwrng *hwrng) > +{ > + struct sun4i_ss_ctx *ss; > + > + ss = container_of(hwrng, struct sun4i_ss_ctx, hwrng); > + get_random_bytes(ss->seed, SS_SEED_LEN); Is it wise to call get_random_bytes once in the init function and never thereafter? This init function may be called during boot time of the kernel at which the input_pool may not yet have received sufficient amounts of entropy. What about registering a callback with add_random_ready_callback and seed again when sufficient entropy was collected? Ciao Stephan