Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752800Ab3FZRt5 (ORCPT ); Wed, 26 Jun 2013 13:49:57 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:53398 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751383Ab3FZRt4 (ORCPT ); Wed, 26 Jun 2013 13:49:56 -0400 Date: Wed, 26 Jun 2013 10:49:54 -0700 From: Greg KH To: Geert Uytterhoeven Cc: Maxime Ripard , Oliver Schinagl , Arnd Bergmann , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , andy.shevchenko@gmail.com, Russell King , Linus Walleij , linux-sunxi@googlegroups.com, Oliver Schinagl , rtc-linux@googlegroups.com, "kernel-janitors@vger.kernel.org" Subject: Re: [PATCH 1/2] Initial support for Allwinner's Security ID fuses Message-ID: <20130626174954.GA2222@kroah.com> References: <1371502778-15849-1-git-send-email-oliver+list@schinagl.nl> <1371502778-15849-2-git-send-email-oliver+list@schinagl.nl> <20130617225847.GA9494@kroah.com> <20130624092942.GG26008@lukather> <20130624160440.GA15201@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3615 Lines: 81 On Wed, Jun 26, 2013 at 11:22:30AM +0200, Geert Uytterhoeven wrote: > On Mon, Jun 24, 2013 at 6:04 PM, Greg KH wrote: > > On Mon, Jun 24, 2013 at 11:29:42AM +0200, Maxime Ripard wrote: > >> On Mon, Jun 17, 2013 at 03:58:47PM -0700, Greg KH wrote: > >> > On Mon, Jun 17, 2013 at 10:59:37PM +0200, Oliver Schinagl wrote: > >> > > +static int __init sunxi_sid_probe(struct platform_device *pdev) > >> > > +{ > >> > > + u8 entropy[SID_SIZE]; > >> > > + unsigned int i; > >> > > + struct resource *res; > >> > > + void __iomem *sid_reg_base; > >> > > + int ret; > >> > > + > >> > > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > >> > > + sid_reg_base = devm_ioremap_resource(&pdev->dev, res); > >> > > + if (IS_ERR(sid_reg_base)) > >> > > + return PTR_ERR(sid_reg_base); > >> > > + platform_set_drvdata(pdev, sid_reg_base); > >> > > + > >> > > + ret = device_create_bin_file(&pdev->dev, &sid_bin_attr); > >> > > + if (ret) > >> > > + return ret; > >> > > >> > You just raced with userspace, having the file show up after the device > >> > was announced to users that it was there. Please use the proper device > >> > file api to add default attributes to prevent this from happening. > >> > >> Sorry if the question looks dumb, but what kind of race can we generate > >> here? > > > > Userspace gets told about the device from the driver core, udev runs and > > reads all of the attributes, then your probe function comes along and > > adds a new attribute. Userspace will then not know about it at all. > > > >> The device_create_bin_file is the last call that we make (if we except > >> the entropy stuff, but it doesn't really matter here), so after we > >> created the file, we have everything properly initialised so that our > >> functions can be called, right? > >> > >> And another dumb question for you, what is the "proper device file API" > >> you are referring to ? :) > > > > Please read Documentation/driver_model/device.txt and see the section on > > Attributes for what to do. If you have specific questions after reading > > that, please let me know. > > Woops, then we have plenty of existing drivers to fix, e.g. all/most RTC drivers > exposing an NVRAM file through sysfs: > > $ git grep -w sysfs_create_bin_file drivers/rtc/ > drivers/rtc/rtc-cmos.c: retval = sysfs_create_bin_file(&dev->kobj, &nvram); > drivers/rtc/rtc-ds1305.c: status = > sysfs_create_bin_file(&spi->dev.kobj, &nvram); > drivers/rtc/rtc-ds1307.c: err = > sysfs_create_bin_file(&client->dev.kobj, ds1307->nvram); > drivers/rtc/rtc-ds1511.c: ret = sysfs_create_bin_file(&pdev->dev.kobj, > &ds1511_nvram_attr); > drivers/rtc/rtc-ds1553.c: ret = sysfs_create_bin_file(&pdev->dev.kobj, > &ds1553_nvram_attr); > drivers/rtc/rtc-ds1742.c: ret = sysfs_create_bin_file(&pdev->dev.kobj, > &pdata->nvram_attr); > drivers/rtc/rtc-m48t59.c: ret = sysfs_create_bin_file(&pdev->dev.kobj, > &m48t59_nvram_attr); > drivers/rtc/rtc-rp5c01.c: error = > sysfs_create_bin_file(&dev->dev.kobj, &priv->nvram_attr); > drivers/rtc/rtc-stk17ta8.c: ret = > sysfs_create_bin_file(&pdev->dev.kobj, &stk17ta8_nvram_attr); > drivers/rtc/rtc-tx4939.c: ret = sysfs_create_bin_file(&pdev->dev.kobj, > &tx4939_rtc_nvram_attr); Yes, they should all be fixed, along with any platform device that creates a sysfs file in the probe function. thanks, greg k-h -- 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/