From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.7 required=3.0 tests=DATE_IN_PAST_96_XX, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DD7B8C2D0EB for ; Sat, 28 Mar 2020 16:44:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BE90E206F6 for ; Sat, 28 Mar 2020 16:44:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727999AbgC1QoP (ORCPT ); Sat, 28 Mar 2020 12:44:15 -0400 Received: from mx.sdf.org ([205.166.94.20]:49806 "EHLO mx.sdf.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727957AbgC1QoN (ORCPT ); Sat, 28 Mar 2020 12:44:13 -0400 Received: from sdf.org (IDENT:lkml@sdf.lonestar.org [205.166.94.16]) by mx.sdf.org (8.15.2/8.14.5) with ESMTPS id 02SGhHat008785 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256 bits) verified NO); Sat, 28 Mar 2020 16:43:17 GMT Received: (from lkml@localhost) by sdf.org (8.15.2/8.12.8/Submit) id 02SGhHox023138; Sat, 28 Mar 2020 16:43:17 GMT Message-Id: <202003281643.02SGhHox023138@sdf.org> From: George Spelvin Date: Wed, 20 Mar 2019 22:50:00 -0400 Subject: [RFC PATCH v1 26/50] drivers/nfc/nfcsim: use prandom_32() for time delay To: linux-kernel@vger.kernel.org, lkml@sdf.org Cc: Thierry Escande , Samuel Ortiz , linux-nfc@lists.01.org Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org get_random_bytes() is expensive crypto-quality seed material. That's not needed for a simple simulation. (Also, a 3-10 ms delay, when converted to jiffies, isn't a lot of granularity. It's 1 jiffy at HZ=100 and 3 jiffies at HZ=250 or HZ=300.) Signed-off-by: George Spelvin Cc: Thierry Escande Cc: Samuel Ortiz Cc: linux-nfc@lists.01.org --- drivers/nfc/nfcsim.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/nfc/nfcsim.c b/drivers/nfc/nfcsim.c index a9864fcdfba6b..eb0a909a25487 100644 --- a/drivers/nfc/nfcsim.c +++ b/drivers/nfc/nfcsim.c @@ -229,8 +229,7 @@ static int nfcsim_send(struct nfc_digital_dev *ddev, struct sk_buff *skb, dev->mode); /* Add random delay (between 3 and 10 ms) before sending data */ - get_random_bytes(&delay, 1); - delay = 3 + (delay & 0x07); + delay = 3 + prandom_u32_max(8); schedule_delayed_work(&dev->send_work, msecs_to_jiffies(delay)); } -- 2.26.0