Received: by 2002:a25:824b:0:0:0:0:0 with SMTP id d11csp1667989ybn; Wed, 25 Sep 2019 23:46:55 -0700 (PDT) X-Google-Smtp-Source: APXvYqwsgU6DB6KryGXFEcbyOmuWhKVth5qbav+ADEyTGK3+BRFG1hB0bQLD3mVDl7TDv3ikx1xR X-Received: by 2002:a50:9e0a:: with SMTP id z10mr1916886ede.202.1569480415153; Wed, 25 Sep 2019 23:46:55 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1569480415; cv=none; d=google.com; s=arc-20160816; b=SADtaWv314oRiTCfaWNGa/QBWruJPsxs+1grTdu5hYh+EOy4cP8TGBOZptpqM8c3jD nfToksnmoz9+w7NXNnZwWGQWSE6tiDQ6assWHD/9/uzgxOtKXgo07aQy+0hG2EX+KVYp CvX35R8GlFJCpBShe0Qmw1HyycJbYArJmAtZpM0EHK8jMpc/hvGaV/ehkl83IKF8mPuv aN7705cGDPfsNMyxhDh1EWnb9XBovJA1R0tvYZrAdvTAaswEQUTNt25wplXg+wfBMeb1 v8pPlG2j1tu3p/kAaR201fjiepuk4XvFNSO+ga6EUyLsIH/sQ15dojHY+/xd+HOKwyMx frZg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:user-agent:in-reply-to :content-disposition:mime-version:references:message-id:subject:cc :to:from:date:dkim-signature; bh=RuU5DS5hKVQNOmOR9I7QRwouMi4bVHIwpfJxJm3OkRA=; b=yjxy7h4HIwmUtgA6fuNXVcGYz0xScO1YnGJ0/xkaT/gTTtb5d5KtYOsupxffSSNwUM qeJy8Y8p/yzalfnQfYQDiqA+uFPOancjVVZ1Q9EcLDePVtXnJFF6hWw5BeFu7aoNz2f4 R9xvcbDJCTEk3C/iuOCo2jbXMOU7vLZhjhfKFGAL5Tj6AB7luC1DC075MVks8YRuDrdQ 7aL5lM2D4QKP7+r13QbpID3CJVeUWBBtPIQL2FBpm5QbxPeIqBz6w8O9BNbFE9iEdbiM R8KjrYy4VqWaFE8Rz1ZDnMTVfQjT+P0CAwPl8cvH4WHOWDe3z/12XHmLrXiuOALWsFk1 M1kQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=AywdPsON; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id y44si804056edb.251.2019.09.25.23.46.29; Wed, 25 Sep 2019 23:46:55 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=AywdPsON; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2503074AbfIXBKZ (ORCPT + 99 others); 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-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