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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 96A9AC43441 for ; Wed, 10 Oct 2018 08:21:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 44C122087D for ; Wed, 10 Oct 2018 08:21:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="cRZ2gI+7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 44C122087D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726960AbeJJPmi (ORCPT ); Wed, 10 Oct 2018 11:42:38 -0400 Received: from mail-pf1-f194.google.com ([209.85.210.194]:40014 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726468AbeJJPmi (ORCPT ); Wed, 10 Oct 2018 11:42:38 -0400 Received: by mail-pf1-f194.google.com with SMTP id s5-v6so2244695pfj.7 for ; Wed, 10 Oct 2018 01:21:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=J926Cf3AaVSnmVsVP5xY8q+xeD1gequYYjoCkCShNv0=; b=cRZ2gI+7kZQ58SOZgvetq655CWihtXnGbJoZTq6rb5D6BKzRdNIlZ4NdvZ68t7APAP a+DdCwTyY2sG8+jk/U6TIM6aFar2h7SClKqrOJpN8bsmF7DmwwN5t61ciP3JBiBKgmhY weCMUrfV+UQ2OSpmC6E0sQOnW7ayZvydSIQ134Jdqe91cLVWKyIDDTuZ1Nh2bkr0ewXx VsAheDRXFAlgm62E4lbBnpnPmTKQExU0yTpmJP74eOMkB4tOsg6ZAUlZ905XCsjxTGym z4uUulSZWLHLj8Za1wiNDcCwHq2c9ixzBBcLkZo+tkW/8VBNSlEepYlgx+ZnavzgK+Bd NNxQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=J926Cf3AaVSnmVsVP5xY8q+xeD1gequYYjoCkCShNv0=; b=jfCvJ29K44ZGdL4n9FBsWADHNULL9VX5Fr9JbJr2IkaFyztaZ9nxm9gRrOaHwpjugs KUaJLz1xFLQVi0g1hAjO0EQetN1c68fkvfsgN9p1Eo1ax2Kt/Itl+meZ86uwRRcbD65M /0VyaftRCThv8V/qglVxx97CzkrdvHA3ASOKqn9LjomSvEBLfKDrFa0vJKLEDPce9Rlk 61y+eVY7PgNJpoCRoek9p48UUb6+q0oTgsXxf+OQcU2Usu1/oYUHxYbrb74H+KJJposA NdZ4nij8+lkDnubSpZQQb2cuV83HQT1tp9/VsiwIAFzhyEFc8fc4dFo7jAVV2LH9QC7H ZUIQ== X-Gm-Message-State: ABuFfogbHixWWTx/4FvpxcU/E80f5QRSZPJSVqCGYcNzpAhC3shoX60E gxOyrcFKJAZqJ/kPaVbLs+0= X-Google-Smtp-Source: ACcGV60Sk/qgDsf0UEZSd1FYMmSpn/DB5XFHER9nZ1xg6sEVoQbs2eKnfP5nSzL2t3cnO+n7VmWA8g== X-Received: by 2002:a63:6203:: with SMTP id w3-v6mr28729367pgb.53.1539159694949; Wed, 10 Oct 2018 01:21:34 -0700 (PDT) Received: from localhost ([175.223.17.147]) by smtp.gmail.com with ESMTPSA id w2-v6sm29215173pfk.140.2018.10.10.01.21.32 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 10 Oct 2018 01:21:33 -0700 (PDT) Date: Wed, 10 Oct 2018 17:21:29 +0900 From: Sergey Senozhatsky To: Petr Mladek Cc: Sergey Senozhatsky , zhe.he@windriver.com, rostedt@goodmis.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 4/4] printk: Give error on attempt to set log buffer length to over 4G Message-ID: <20181010082129.GA631@jagdpanzerIV> References: <1538239553-81805-1-git-send-email-zhe.he@windriver.com> <1538239553-81805-4-git-send-email-zhe.he@windriver.com> <20181008135916.gg4kkmoki5bgtco5@pathway.suse.cz> <20181008145950.GA1473@tigerII.localdomain> <20181009130538.7rtd3du2d7l6m63w@pathway.suse.cz> <20181009135758.GA1419@tigerII.localdomain> <20181010080932.h6nln2qsgg4oef4l@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181010080932.h6nln2qsgg4oef4l@pathway.suse.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (10/10/18 10:09), Petr Mladek wrote: > > > +#define LOG_BUF_LEN_MAX (u32)(1 << 31) > > [..] > > > + if (size > (u64)LOG_BUF_LEN_MAX) { > > > + size = (u64)LOG_BUF_LEN_MAX; > > > + pr_err("log_buf over 2G is not supported.\n"); > > > + } > > > > Why not INT_MAX? > > INT_MAX is 0x7fffffff but we need 0x80000000. I did not find > any predefined macro. Hmm, OK. I need to think about it more. > > > + pr_info("log_buf_len: %u bytes\n", log_buf_len); > > > + pr_info("early log buf free: %u(%u%%)\n", > > > free, (free * 100) / __LOG_BUF_LEN); > > > > Can 'free * 100' overflow? > > Good question. It uses the size of the static buffer. If I count > correctly then we are on the safe side because LOG_BUF_SHIFT > is limited by > > range 12 25 I didn't know there was Kconfig "range" :) $ echo $(((1<<25)*100)) 3355443200 -ss