linux-kernel - Re: drivers/firmware/google/vpd.c: duplicate sysfs file

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Date:   Mon, 13 Nov 2017 11:04:00 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     Guenter Roeck <groeck@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Guenter Roeck <groeck@...omium.org>,
        Wei-Ning Huang <wnhuang@...gle.com>
Subject: Re: drivers/firmware/google/vpd.c: duplicate sysfs file

On Mon, Nov 13, 2017 at 10:18:35AM -0800, Randy Dunlap wrote:
> On 11/13/2017 06:41 AM, Guenter Roeck wrote:
> > 
> > 
> > On Sun, Nov 12, 2017 at 10:36 PM, Randy Dunlap <rdunlap@...radead.org <mailto:rdunlap@...radead.org>> wrote:
> > 
> >     sysfs: cannot create duplicate filename '/devices/platform/vpd'
> > 
> >     on the second load of this driver.  I.e.,
> > 
> >     modprobe vpd-sysfs
> >     rmmod vpd-sysfs
> >     modprobe vpd-sysfs
> >     [boom]
> > 
> > Neither the platform device nor the platform driver driver are ever unregistered, so this isn't entirely surprising. I'll try to reproduce and send a patch.
> 
> 
> Seems to be a common theme:
> 
> google> grep --color=never "platform.*register" *.c
> coreboot_table-acpi.c:	return platform_driver_register(&coreboot_table_acpi_driver);
> coreboot_table-of.c:	return platform_driver_register(&coreboot_table_of_driver);

These are not unloadable (for better or worse) - they do not have
module_exit() in them.

> 
> gsmi.c:	gsmi_dev.pdev = platform_device_register_full(&gsmi_dev_info);
> gsmi.c:	platform_device_unregister(gsmi_dev.pdev);
> gsmi.c:	platform_device_unregister(gsmi_dev.pdev);
> [looks good]
> 
> memconsole-coreboot.c:	pdev = platform_device_register_simple("memconsole", -1, NULL, 0);
> memconsole-coreboot.c:	platform_driver_register(&memconsole_driver);

Same here: not unloadable.

> 
> vpd.c:	pdev = platform_device_register_simple("vpd", -1, NULL, 0);
> vpd.c:	platform_driver_register(&vpd_driver);

Arguably this should not even be a platform driver, there is no hardware
behind it. I was planning on purring some notifiers into coreboot table
driver and using notifiers to attach vpd to them. -ENOTIME though.

Thanks.

-- 
Dmitry