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SubjectRe: drivers/firmware/google/vpd.c: duplicate sysfs file
On Mon, Nov 13, 2017 at 12:14:41PM -0800, Guenter Roeck wrote:
> The sysfs warning, yes. However, after unbinding and rebinding the
> driver, "cat /sys/firmware/vpd/rw_raw" will result in a crash.
>
> Sequence:
>
> echo vpd > /sys/bus/platform/drivers/vpd/unbind
> echo vpd > /sys/bus/platform/drivers/vpd/bind # <-- nasty message
>
> cat /sys/firmware/vpd/rw_raw # <-- crash

I'd disable unbind (.suppress_bind_attrs = true) and commented out
unload for now. And then looked into fixing properly.

>
> Guenter
>
> On Mon, Nov 13, 2017 at 11:23 AM, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> > On Mon, Nov 13, 2017 at 11:09:21AM -0800, Guenter Roeck wrote:
> >> On Mon, Nov 13, 2017 at 11:04 AM, Dmitry Torokhov
> >> <dmitry.torokhov@gmail.com> wrote:
> >> >
> >> > 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@infradead.org <mailto:rdunlap@infradead.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.
> >> >
> >> Two options for now: clean it up and make it unloadable, or make it bool
> >> and drop the exit function. Any preference ?
> >>
> >> The problem is easy to reproduce even with the driver is built into
> >> the kernel with a simple unbind/bind sequence. And after the unbind,
> >> it is easy to crash the system since the sysfs attributes are still there.
> >
> > The kernel should not 'crash', just spit out a nasty warning, right?
> >
> > thanks,
> >
> > greg k-h

--
Dmitry

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