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_HELO_NONE,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 EBAADC31E51 for ; Tue, 18 Jun 2019 04:55:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B66E82085A for ; Tue, 18 Jun 2019 04:55:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="BCgORY8f" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728293AbfFREvW (ORCPT ); Tue, 18 Jun 2019 00:51:22 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:37002 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725870AbfFREvW (ORCPT ); Tue, 18 Jun 2019 00:51:22 -0400 Received: by mail-pf1-f196.google.com with SMTP id 19so6903962pfa.4 for ; Mon, 17 Jun 2019 21:51:22 -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=GcQlY8S/p+kxFAnMkubPgYwK7VdqjVATnBI9h9/SPA8=; b=BCgORY8fG3p2oZw4qFVaCKNKF/8FqPeWfMM2TL82ob4r8YP15GX8hY1rRi6tjCHne0 6/p5Tp4P33PsKTtiG8glwrn63CWlEDeK7z//GlWuLn/bz9n8lpQ89oss+iskkNCc+O1A A6ZA0M+jt149ybUbHdSlhJqSk+DlwugQxYeivu7pcDMa9h/ch4aDl9TNhG8OaRpUmWQ+ h60lxa2M9X4uvJcPIBqAGFnBitHlZTwuLhOhU8wLF0vuf1/DTgjV1/moZwpu0zOw6gts YWBO7DzOOr7UnnWe6Injlrgx+BlIhdOAybooB7Y0IYCs4944Uw8OgNxX7Fl+8v6M9+WR zKxg== 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=GcQlY8S/p+kxFAnMkubPgYwK7VdqjVATnBI9h9/SPA8=; b=GAPgHwbRrl3GcghCgPtN1pjMW1dUIznto9iW/dOHVmbYdvbJ6fvGjZ14nAVuscQUI/ W3E7aGqp5jpC8UCDl70a0RTggCZPv6NcMdvh7YEOCV6hlyQqJWxBa1E7WtSfP27yLZJn Zb7cGZZMx9agX81rbQQ7MFKpuPE+BzN/gQufN+Ju81p6/+CJc2jRL6YIxFQPglAUdZpk 4FQ8s/1U5jXGDbrWUYfWy3YcGu7kMxRU1kBBTpcr7QiLIscmkzC3qZlYXtSiQwNTV/OC mOvFt64qiALic1YxSQlRqWrUA2G0+XWuOcbv8hPvRidszFjVUlmFIBb1kWgbDo/qjoBw 1Nuw== X-Gm-Message-State: APjAAAUISco5jIzPQfYOTCCXkGsEHWEVpy1JMZXqHNhF6zpcTotI5Awy jlGqcsUTiCYYXRoj6UUOpnM= X-Google-Smtp-Source: APXvYqzEDDQ/Tq39/8bkhp/hHoPl7qt/cst7WCob3xQfRP8I7Bffo+94PULeO/aAJi0RBlFSAruRQQ== X-Received: by 2002:a17:90a:db44:: with SMTP id u4mr2965916pjx.52.1560833481851; Mon, 17 Jun 2019 21:51:21 -0700 (PDT) Received: from localhost ([175.223.20.188]) by smtp.gmail.com with ESMTPSA id e184sm18115681pfa.169.2019.06.17.21.51.20 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 17 Jun 2019 21:51:20 -0700 (PDT) Date: Tue, 18 Jun 2019 13:51:17 +0900 From: Sergey Senozhatsky To: John Ogness Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Linus Torvalds , Greg Kroah-Hartman , Andrea Parri , Thomas Gleixner , Sergey Senozhatsky Subject: Re: [RFC PATCH v2 1/2] printk-rb: add a new printk ringbuffer implementation Message-ID: <20190618045117.GA7419@jagdpanzerIV> References: <20190607162349.18199-1-john.ogness@linutronix.de> <20190607162349.18199-2-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190607162349.18199-2-john.ogness@linutronix.de> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello John, On (06/07/19 18:29), John Ogness wrote: [..] > + struct prb_reserved_entry e; > + char *s; > + > + s = prb_reserve(&e, &rb, 32); > + if (s) { > + sprintf(s, "Hello, world!"); > + prb_commit(&e); > + } A nit: snprintf(). sprintf() is tricky, it may write "slightly more than was anticipated" bytes - all those string_nocheck(" disabled"), error_string("pK-error"), etc. [..] > +Sample reader code:: > + > + DECLARE_PRINTKRB_ENTRY(entry, 128); > + DECLARE_PRINTKRB_ITER(iter, &test_rb, &entry); > + u64 last_seq = 0; > + int len; > + char *s; > + > + prb_for_each_entry(&iter, len) { > + if (entry.seq - last_seq != 1) { > + printf("LOST %llu ENTRIES\n", > + entry.seq - (last_seq + 1)); > + } > + last_seq = entry.seq; > + > + s = (char *)&entry.buffer[0]; > + if (len >= 128) > + s[128 - 1] = 0; > + printf("data: %s\n", s); > + } How are we going to handle pr_cont() loops? print_modules() preempt_disable(); list_for_each_entry_rcu(mod, &modules, list) { pr_cont(" %s%s", mod->name, module_flags(mod, buf)); } preempt_enable(); -ss