From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754842AbcIPGH3 (ORCPT ); Fri, 16 Sep 2016 02:07:29 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:55779 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751690AbcIPGHV (ORCPT ); Fri, 16 Sep 2016 02:07:21 -0400 Date: Fri, 16 Sep 2016 08:07:18 +0200 From: Pavel Machek To: David Lechner Cc: Jacek Anaszewski , Richard Purdie , linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org, Marcel Holtmann Subject: Re: [PATCH v3] leds: Introduce userspace leds driver Message-ID: <20160916060718.GD13205@amd> References: <1473439776-15655-1-git-send-email-david@lechnology.com> <80597ded-f4b4-2990-3eae-e72276296d1a@samsung.com> <20160915130831.GJ13132@amd> <313cbae5-fd66-f0ae-79a9-a3f4273d6f9c@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! +static ssize_t uleds_read(struct file *file, char __user *buffer, size_t count, + loff_t *ppos) +{ + struct uleds_device *udev = file->private_data; + ssize_t retval; + + if (count == 0) + return 0; + + if (count != 1) + return -EINVAL; This is quite anti-social. You are free to return 1 byte on any read (short read), but please allow reads with bigger buffers. Thanks, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html