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=-5.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 CF64FC282DD for ; Thu, 9 Jan 2020 23:41:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F3B62073A for ; Thu, 9 Jan 2020 23:41:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578613312; bh=V2TU7bmhK2rc0g3gTmxhO+8joHF8QS5c5TW8/rrWMSY=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=MBXG9Rkol5Oi4Gz5NB9x2Y2+bCSCapCDn1rBWQtr3qRRqgjSCwQZxSGeqkWzWVBjX X/ca3pecJW/kmhws9W4HEKOtNWiQB2oJnqhQhGTT8gha0goizG4T8JPmdGWj5XclG3 xZofgXmlr4eweIH8YhpET5VBcrpl3ZIBkFz8iD3I= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729537AbgAIXlv (ORCPT ); Thu, 9 Jan 2020 18:41:51 -0500 Received: from mail-lj1-f195.google.com ([209.85.208.195]:41259 "EHLO mail-lj1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725840AbgAIXlv (ORCPT ); Thu, 9 Jan 2020 18:41:51 -0500 Received: by mail-lj1-f195.google.com with SMTP id h23so159329ljc.8 for ; Thu, 09 Jan 2020 15:41:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=vfpfB0heb47nMgztDPhE6QVnvLuPdQSEP2b5ktH3qTQ=; b=JMCnPNu2FZKj4HmJcziRUk5O9yUgf94qqHvorN+sh+nwIlFA9njr0QdL7pC3p3/22w aUadfTYO3UAxVMhaO3fZYlehOasRUNSFGYP7qnx2IquOYnp2i+zuuvu6GIdGkOF22lTh KiDNWsr/WehUgh2ES9kDZ/ClZTU0gpsXokVzM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=vfpfB0heb47nMgztDPhE6QVnvLuPdQSEP2b5ktH3qTQ=; b=gpwxqskP5reHSvYOWCan1w4p0NjjxBS728gocok8j+pORlHmVuTMHiRy8w/ivEEIkS V06kLFav1mE+RKdo1503NE97ua7y0Q26dxrMTGxz4n2LPawEgxUt7waKNz3YiDlhkGC0 zHnfPHKLp0QOGKkjH4uN1oRjujVGSLGeBGBTAfupdmOEsMlxEvjd03/7c5COTZb4XQqF im5UY3a7fIi3CYuQqP4tZlkkLGccX1fPmDN8KA+2n/ncVhrvL9A3kJrqWcfnjfHWQb4C 0iLCMoRBrXrkwflwe04N01RsfHiPeNXeZNJfgSKbvNeSdH8gDTCVjnLjxpCUnmOSb2ax 3gvQ== X-Gm-Message-State: APjAAAUldJnPYeMr76cszxigRPdd91DfXwGuCuirqrdskVIpV46JMfog 4HkNolA066WnVpfhTcTJOMRzUd4eHBQ= X-Google-Smtp-Source: APXvYqzfaqwDPc7l9guChin11/i0VFJqAbdxFPQ2yBVdoiWc/00PpY20qBIAwVUYR/ii7FSeO5jo+A== X-Received: by 2002:a2e:548:: with SMTP id 69mr352956ljf.67.1578613309208; Thu, 09 Jan 2020 15:41:49 -0800 (PST) Received: from mail-lj1-f178.google.com (mail-lj1-f178.google.com. [209.85.208.178]) by smtp.gmail.com with ESMTPSA id w20sm64349ljo.33.2020.01.09.15.41.47 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 09 Jan 2020 15:41:48 -0800 (PST) Received: by mail-lj1-f178.google.com with SMTP id r19so183900ljg.3 for ; Thu, 09 Jan 2020 15:41:47 -0800 (PST) X-Received: by 2002:a2e:8946:: with SMTP id b6mr367415ljk.1.1578613307533; Thu, 09 Jan 2020 15:41:47 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Linus Torvalds Date: Thu, 9 Jan 2020 15:41:31 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [GIT PULL] HID fixes To: Jiri Kosina Cc: Marcel Holtmann , Dmitry Torokhov , Linux Kernel Mailing List , Benjamin Tissoires Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 9, 2020 at 3:36 PM 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.. Linus