Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755803AbaDNQ1O (ORCPT ); Mon, 14 Apr 2014 12:27:14 -0400 Received: from verein.lst.de ([213.95.11.211]:49663 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755747AbaDNQ1H (ORCPT ); Mon, 14 Apr 2014 12:27:07 -0400 Date: Mon, 14 Apr 2014 18:27:03 +0200 From: Torsten Duwe To: "H. Peter Anvin" Cc: Andy Lutomirski , "Theodore Ts'o" , Greg Kroah-Hartman , Andrew Morton , Matt Mackall , Herbert Xu , Arnd Bergmann , Rusty Russell , Satoru Takeuchi , ingo.tuchscherer@de.ibm.com, linux-kernel@vger.kernel.org, Hans-Georg Markgraf , Gerald Schaefer , Martin Schwidefsky , Heiko Carstens , Joe Perches Subject: [PATCH v4 03/03]: hwrng: khwrngd derating per device Message-ID: <20140414162703.GF29351@lst.de> References: <20140321142950.GI1763@lst.de> <20140321143342.GK1763@lst.de> <533375C1.5060904@mit.edu> <158d2776-1ea4-4f32-a9e9-0488047e6b70@email.android.com> <20140414160211.GE711@lst.de> <7b22b881-9359-42c9-a632-6a8cbdb13b71@email.android.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7b22b881-9359-42c9-a632-6a8cbdb13b71@email.android.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch introduces a derating factor to struct hwrng for the random bits going into the kernel input pool, and a common default derating for drivers which do not specify one. Signed-off-by: Torsten Duwe --- drivers/char/hw_random/core.c | 11 ++++++++++- include/linux/hw_random.h | 3 +++ 2 files changed, 13 insertions(+), 1 deletion(-) --- linux/include/linux/hw_random.h.orig +++ linux/include/linux/hw_random.h @@ -29,6 +29,8 @@ * @read: New API. drivers can fill up to max bytes of data * into the buffer. The buffer is aligned for any type. * @priv: Private data, for use by the RNG driver. + * @derating: Estimation of true entropy in RNG's bitstream + * (per mill). */ struct hwrng { const char *name; @@ -38,6 +39,7 @@ struct hwrng { int (*data_read)(struct hwrng *rng, u32 *data); int (*read)(struct hwrng *rng, void *data, size_t max, bool wait); unsigned long priv; + unsigned short derating; /* internal. */ struct list_head list; --- linux/drivers/char/hw_random/core.c.orig +++ linux/drivers/char/hw_random/core.c @@ -56,11 +56,15 @@ static LIST_HEAD(rng_list); static DEFINE_MUTEX(rng_mutex); static int data_avail; static u8 *rng_buffer, *rng_fillbuf; -static unsigned short derating_current = 700; /* an arbitrary 70% */ +static unsigned short derating_current; +static unsigned short derating_default = 0; /* default to "off" */ module_param(derating_current, ushort, 0644); MODULE_PARM_DESC(derating_current, "current hwrng entropy estimation per mill"); +module_param(derating_default, ushort, 0644); +MODULE_PARM_DESC(derating_default, + "default entropy content of hwrng per mill"); static void start_khwrngd(void); @@ -79,6 +83,11 @@ static inline int hwrng_init(struct hwrn if (err) return err; + derating_current = rng->derating ? : derating_default; + derating_current &= 1023; + + if (derating_current == 0 && hwrng_fill) + kthread_stop(hwrng_fill); if (derating_current > 0 && !hwrng_fill) start_khwrngd(); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/