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=-9.0 required=3.0 tests=BUG6152_INVALID_DATE_TZ_ABSURD,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,INVALID_DATE_TZ_ABSURD,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 833E0C433FF for ; Wed, 7 Aug 2019 22:27:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5DA4B214C6 for ; Wed, 7 Aug 2019 22:27:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389502AbfHGW13 (ORCPT ); Wed, 7 Aug 2019 18:27:29 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:51819 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388848AbfHGW12 (ORCPT ); Wed, 7 Aug 2019 18:27:28 -0400 Received: from [5.158.153.52] (helo=g2noscherz.tec.linutronix.de.) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.80) (envelope-from ) id 1hvUOg-0007mg-R5; Thu, 08 Aug 2019 00:27:08 +0200 From: John Ogness To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Linus Torvalds , Greg Kroah-Hartman , Andrea Parri , Thomas Gleixner , Sergey Senozhatsky , Brendan Higgins Subject: [RFC PATCH v4 5/9] printk-rb: remove extra data buffer size allocation Date: Thu, 8 Aug 2019 00:32:30 +0206 Message-Id: <20190807222634.1723-6-john.ogness@linutronix.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190807222634.1723-1-john.ogness@linutronix.de> References: <20190807222634.1723-1-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The buffer for the raw data storage included extra space at the end for a long. This was meant to guarantee space for the ID of a wrapping datablock. However, since datablocks are padded and the dataring is implemented such that no datablock can end at exactly the end of the data buffer: DATA_WRAPS(begin) != DATA_WRAPS(next) there will always be space available for the ID of a wrapping datablock. Signed-off-by: John Ogness --- kernel/printk/ringbuffer.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/printk/ringbuffer.h b/kernel/printk/ringbuffer.h index 462b4d3a3ee2..698d2328ea9e 100644 --- a/kernel/printk/ringbuffer.h +++ b/kernel/printk/ringbuffer.h @@ -175,8 +175,7 @@ struct dr_desc *prb_getdesc(unsigned long id, void *arg); * * descriptor 1 will be the next descriptor */ #define DECLARE_PRINTKRB(name, avgdatabits, descbits) \ -char _##name##_data[(1 << ((avgdatabits) + (descbits))) + \ - sizeof(long)] \ +char _##name##_data[1 << ((avgdatabits) + (descbits))] \ __aligned(__alignof__(long)); \ struct prb_desc _##name##_descs[1 << (descbits)] = { \ { \ -- 2.20.1