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=-7.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 A4BC3C282DD for ; Fri, 10 Jan 2020 14:31:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6D93E2080D for ; Fri, 10 Jan 2020 14:31:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578666676; bh=HgPahpXdshZgo/Yb5Xs234RcEyVF4p1fdHTEKPXXC+A=; h=Date:From:To:cc:Subject:In-Reply-To:References:List-ID:From; b=avfsxbEcu2F8nH+eEH+R1i7XExFI4pIiqN0Np97AdHcu++p/uzCvoUvyilX0gbh21 aUbzOk8AhP/66Y3/2X37GDI10tOS9BvMrnKxI2P8pAHf+qPK6OxmRtM/FhrkbQAYKa iswqV9/exJB2+UgmifVL58NQLarIsewVl7X7XPmA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727753AbgAJObP (ORCPT ); Fri, 10 Jan 2020 09:31:15 -0500 Received: from mail.kernel.org ([198.145.29.99]:58248 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726773AbgAJObP (ORCPT ); Fri, 10 Jan 2020 09:31:15 -0500 Received: from pobox.suse.cz (prg-ext-pat.suse.com [213.151.95.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7ED0C2077C; Fri, 10 Jan 2020 14:31:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578666674; bh=HgPahpXdshZgo/Yb5Xs234RcEyVF4p1fdHTEKPXXC+A=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=lS8xc2Q2D11wQrtJIm28CF2qqKfz4e3KiC3sYg0ZJ+ljp2QwIZt9Q/sOzi4ezn5Oh MQbOkgJWEWhw0NBLi9D/nERGeL6GkhdZn2RpJAjNclZVoG7XAFnY8EhVdQuqGIvVJU 9+Upe3RLWUbSE/EDzsxYU8KNb0HiCTvUwwf0tt9c= Date: Fri, 10 Jan 2020 15:31:10 +0100 (CET) From: Jiri Kosina To: Linus Torvalds cc: Marcel Holtmann , Dmitry Torokhov , Linux Kernel Mailing List , Benjamin Tissoires Subject: Re: [GIT PULL] HID fixes In-Reply-To: Message-ID: References: User-Agent: Alpine 2.21 (LSU 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 9 Jan 2020, Linus Torvalds wrote: > > Now, good source code presumably notices EPOLLERR and handles it. So > > it _shouldn't_ matter what the kernel does if an error occurs. I > > haven't checked what people _actually_ do, tnough. I worry sometimes > > that user space just looks at EPOLLIN sees it not being set, and gets > > stuck in a busy loop polling in case of errors. > > Googling around for it, I find this, for example: > > https://github.com/scylladb/seastar/issues/309 > > and yes, I think that's technically a user space bug, but it's very > much an example of this: they expect to get errors through read() or > write() calls, and get confused when poll() does not say that the fd > is readable or writable. > > I don't know how common this is, but it didn't take a _lot_ of > googling for me to find that one.. Right, I think it's quite a convicing argument, and the issue is rather easy to avoid. I'll fix that up in the patch and send a fixup pull request to you later today. Marcel, please speak up if you have other plans. -- Jiri Kosina SUSE Labs