From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932258Ab2HOT4x (ORCPT ); Wed, 15 Aug 2012 15:56:53 -0400 Received: from mail.windriver.com ([147.11.1.11]:37423 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932104Ab2HOTxA (ORCPT ); Wed, 15 Aug 2012 15:53:00 -0400 From: Paul Gortmaker To: , CC: Tony Luck , "Theodore Ts'o" , Paul Gortmaker Subject: [v2.6.34-stable 162/165] random: Add comment to random_initialize() Date: Wed, 15 Aug 2012 15:48:26 -0400 Message-ID: <1345060109-9187-163-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.7.12.rc2 In-Reply-To: <1345060109-9187-1-git-send-email-paul.gortmaker@windriver.com> References: <1345060109-9187-1-git-send-email-paul.gortmaker@windriver.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tony Luck ------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. ------------------- commit cbc96b7594b5691d61eba2db8b2ea723645be9ca upstream. Many platforms have per-machine instance data (serial numbers, asset tags, etc.) squirreled away in areas that are accessed during early system bringup. Mixing this data into the random pools has a very high value in providing better random data, so we should allow (and even encourage) architecture code to call add_device_randomness() from the setup_arch() paths. However, this limits our options for internal structure of the random driver since random_initialize() is not called until long after setup_arch(). Add a big fat comment to rand_initialize() spelling out this requirement. Suggested-by: Theodore Ts'o Signed-off-by: Tony Luck Signed-off-by: Theodore Ts'o Signed-off-by: Paul Gortmaker --- drivers/char/random.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/char/random.c b/drivers/char/random.c index 1644b8e..7e19406 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1088,6 +1088,16 @@ static void init_std_data(struct entropy_store *r) mix_pool_bytes(r, utsname(), sizeof(*(utsname())), NULL); } +/* + * Note that setup_arch() may call add_device_randomness() + * long before we get here. This allows seeding of the pools + * with some platform dependent data very early in the boot + * process. But it limits our options here. We must use + * statically allocated structures that already have all + * initializations complete at compile time. We should also + * take care not to overwrite the precious per platform data + * we were given. + */ static int rand_initialize(void) { init_std_data(&input_pool); -- 1.7.12.rc2