Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758634Ab2JSKfe (ORCPT ); Fri, 19 Oct 2012 06:35:34 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:47207 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758605Ab2JSKfc (ORCPT ); Fri, 19 Oct 2012 06:35:32 -0400 MIME-Version: 1.0 In-Reply-To: <507FD4EB.1080204@antcom.de> References: <1350477107-26512-1-git-send-email-stigge@antcom.de> <1350477107-26512-3-git-send-email-stigge@antcom.de> <20121017190520.GC25996@kroah.com> <507FD4EB.1080204@antcom.de> Date: Fri, 19 Oct 2012 12:35:31 +0200 Message-ID: Subject: Re: [PATCH RFC 02/15 v5] gpio: Add sysfs support to block GPIO API From: Linus Walleij To: Roland Stigge , Greg KH , Grant Likely Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, w.sang@pengutronix.de, jbe@pengutronix.de, plagnioj@jcrosoft.com, highguy@gmail.com, broonie@opensource.wolfsonmicro.com, daniel-gl@gmx.net, rmallon@gmail.com Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1261 Lines: 33 On Thu, Oct 18, 2012 at 12:07 PM, Roland Stigge wrote: > On 10/17/2012 09:05 PM, Greg KH wrote: >>> >>> + if (value != exported) { >>> + if (value) >>> + status = gpio_block_value_export(block); >>> + else >>> + status = gpio_block_value_unexport(block); >> >> That looks like a recipie for disaster. Why do you allow userspace to >> do this? > > Exporting for gpio blocks is done as follows: writing "1" to the > "exported" _device_ attribute of the gpio block creates the "values" > attribute and at the same time requests the whole block (including all > of its gpios) as "sysfs". To me it reads like Greg's comment is basically pinpointing a flaw in Brownell's initial design of gpio sysfs: that new sysfs files are created and destroyed by writing into sysfs */export files from userspace? See commit: d8f388d8dc8d4f36539dd37c1fff62cc404ea0fc The block GPIO stuff is just following that design pattern. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/