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=-2.2 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_SANE_1 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 7DC70C432C1 for ; Tue, 24 Sep 2019 01:10:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 40DB420673 for ; Tue, 24 Sep 2019 01:10:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="AywdPsON" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2503711AbfIXBKZ (ORCPT ); Mon, 23 Sep 2019 21:10:25 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:43002 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388676AbfIXBKY (ORCPT ); Mon, 23 Sep 2019 21:10:24 -0400 Received: by mail-pl1-f195.google.com with SMTP id e5so146387pls.9 for ; Mon, 23 Sep 2019 18:10:23 -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=RuU5DS5hKVQNOmOR9I7QRwouMi4bVHIwpfJxJm3OkRA=; b=AywdPsONcoTFzd5M+ALTAVQ97uLpYfsaV/jDdSwr9LWXCg3PzzKUAntPuWCBMmrocK IGJyhs7gVtvNWPfkTch5ETh8ZyZA8eSZMi0s1Q+mcxRP5b//L7oMhAkvvLRFU7h72449 M1NR6ynqJC+HjW0k4K1R82AX+tCii6y8ObqmEOpBaYyvUd/SRgBIptVqwIskq7VMKJ+o HFdRSvYsrICgYNP9/WhTKDYhNmGhPhMUarsQVhwh9uBerwp1K1kqp+iK+MpGakbFlrkP XvxII8Rk/3krtzcFQM7dvwWW6ZbWvJp7cCrbPALFZwv04PAwvkcV9mngTqf9pboXRZrd SVdQ== 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=RuU5DS5hKVQNOmOR9I7QRwouMi4bVHIwpfJxJm3OkRA=; b=SFXETujWgvrV2OHDa4mv1zhyjAsd6VzgKp08Q74JNZXno3aiYGF/h1+2ixL7pAg6Oz gUAOs/et2JaGrk5FHjcLJiMSxZMc+78hr2AU0HpaC2NJczRqY7z0OD8Y/1c/WBo3BzOS Z6M/NZYv7AVbh6HZQfEsUpk7fGBoftTQHEDgg7hPNWleVDGmxodyzsIb5X3q3kzeoCcL we25JeGkT+JkUt6Ykq+/twIFw6sF6EhW67dyiiGxDTYdUIKaRGM4c6BxjAV02TdpzqIm 5qCITdsWz5XYT5kbQgniLt0MiO1PzxN7i3ooeLNMWznkf+ThWueh3OPSSMWAUjXBYEya bnHw== X-Gm-Message-State: APjAAAXNovXgsyC91Jmf1mvDLiAA1EInZgv1/ad3ssE6q+sy4fzArPrP 5U2hmSNnennTiJHXDBuJDmE= X-Google-Smtp-Source: APXvYqx/J5YdTZCHbrM1AgxVmNN74siiz7UEiiPSiF0tBD8eSYjpGAs7onSfVbUF8zeY6X/UyW6qrg== X-Received: by 2002:a17:902:aa08:: with SMTP id be8mr354920plb.82.1569287422748; Mon, 23 Sep 2019 18:10:22 -0700 (PDT) Received: from localhost ([110.70.15.91]) by smtp.gmail.com with ESMTPSA id e4sm108590pgn.88.2019.09.23.18.10.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Sep 2019 18:10:21 -0700 (PDT) Date: Tue, 24 Sep 2019 10:10:18 +0900 From: Sergey Senozhatsky To: He Zhe Cc: Sergey Senozhatsky , pmladek@suse.com, sergey.senozhatsky@gmail.com, rostedt@goodmis.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] printk: Fix unnecessary returning broken pipe error from devkmsg_read Message-ID: <20190924011018.GA3864@jagdpanzerIV> References: <1568813503-420025-1-git-send-email-zhe.he@windriver.com> <20190923100513.GA51932@jagdpanzerIV> <027b2f0d-b7dc-4e76-22a7-ce80c9a0aade@windriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <027b2f0d-b7dc-4e76-22a7-ce80c9a0aade@windriver.com> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (09/23/19 18:45), He Zhe wrote: > I think it is NOT necessary to inform user-space, when it just wants to read > from the beginning of the buffer, that the buffer has changed since the time > point when it issues the action of reading. The point here is not to notify user space that the logbuf has changed, but to notify user space that unseen messages are gone, we lost them, user space will never read them. -ss