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 2C63DC48BD5 for ; Tue, 25 Jun 2019 06:45:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EEE642085A for ; Tue, 25 Jun 2019 06:45:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="sTuszrkc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729584AbfFYGpt (ORCPT ); Tue, 25 Jun 2019 02:45:49 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:41725 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726551AbfFYGpt (ORCPT ); Tue, 25 Jun 2019 02:45:49 -0400 Received: by mail-pg1-f195.google.com with SMTP id y72so8430478pgd.8 for ; Mon, 24 Jun 2019 23:45:48 -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=CAifnpJEO2ZMcI2CGYepWiuJi+SsX7+yIHhOSV88sqY=; b=sTuszrkcp+SlrQ+SCcJ+X7Xy8O/avyX6FScMpy8MoB341G0m8jH3c4Po+dDoRo9KwT yhW2ybt9aVuJW/tJyS+wvOaIzLV6BgPisDUGF1adW9y85hL1JWleJx2OMMCjw9URNT4t /X5gIHdfIAn/9kEEUZzFKYZXcc4C0YjqgKUpg07PP6uXLXrVVyYrfIvxPZ/ZeaniUqDc 0vOKm4GqPr0sHcs2vf65dtRqtH7SvQTRTgpDqREP5YO0od01pTt/sbrL6sj4Jfcngb0a r7nkl/HiKorDjL7CIZ8Z583Lot39dplPAHoQf1ZfFitWKLVE8oj/0VrXp1OUplL16Lwv Qc7w== 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=CAifnpJEO2ZMcI2CGYepWiuJi+SsX7+yIHhOSV88sqY=; b=NONrSW92iBR4eU4dnCC0vIjqoamD6Ul/WQBgfVhqCTcMjHHpW88wzi/7gm2J4nkaVZ WumDAofe920pKjZoCnh5ew4Jg09/xZvl6w9Zj25YkdkYmxVQuJq6ay8RoQXrc6AnKRXP l/D9vXXbfTQIa9wk+VceN42KCRuEcUNPlxlP3G2QAiQ/Y7eGRVwGz5OYvUE/bzj/Eq8H qGu91b7PVWcXpNBvNe0Iwasc64RKfCIQskWofW8yF/czFWLcBusA+/17zATlrR5j0qWp 4Qc5O9OaBTw57cEOf9Eq35IQfuqomDw0BjSW0GcXDHws3LOkhKkeydmtuRtxrSs3WmV1 3gqA== X-Gm-Message-State: APjAAAWSF2yT0weu8dfSM2TXBLp1skV9Yex0VF5K/C37vLXtczIeArbh vMeiPmcp1Ln783WLVQr+NG0= X-Google-Smtp-Source: APXvYqwh1E4uziir/9Y2AHlTpJYc8vgrFWWKVZUDasoTciXkNv1oNoktXcqISbo4pxdreleHfpgtPw== X-Received: by 2002:a63:490a:: with SMTP id w10mr36637630pga.6.1561445148568; Mon, 24 Jun 2019 23:45:48 -0700 (PDT) Received: from localhost ([175.223.22.38]) by smtp.gmail.com with ESMTPSA id y12sm12446187pgi.10.2019.06.24.23.45.46 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Mon, 24 Jun 2019 23:45:47 -0700 (PDT) Date: Tue, 25 Jun 2019 15:45:43 +0900 From: Sergey Senozhatsky To: John Ogness Cc: Sergey Senozhatsky , linux-kernel@vger.kernel.org, Peter Zijlstra , Petr Mladek , 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: <20190625064543.GA19050@jagdpanzerIV> References: <20190607162349.18199-1-john.ogness@linutronix.de> <20190607162349.18199-2-john.ogness@linutronix.de> <20190618045117.GA7419@jagdpanzerIV> <87imt2bl0k.fsf@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87imt2bl0k.fsf@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 On (06/19/19 00:12), John Ogness wrote: > On 2019-06-18, Sergey Senozhatsky 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. > > Agreed. Documentation should show good examples. In vprintk_emit(), are we going to always reserve 1024-byte records, since we don't know the size in advance, e.g. printk("%pS %s\n", regs->ip, current->name) prb_reserve(&e, &rb, ????); or are we going to run vscnprintf() on a NULL buffer first, then reserve the exactly required number of bytes and afterwards vscnprintf(s) -> prb_commit(&e)? -ss