Re: x86, microcode: Conversion from sysdev class caused regression

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Apr 11, 2012 at 06:38:50PM +0200, Andreas Herrmann wrote:
> Hi,
> 
> commit 8a25a2fd126c621f44f3aeaef80d51f00fc11639 (cpu: convert 'cpu'
> and 'machinecheck' sysdev_class to a regular subsystem) causes a
> regression in the CPU microcode loader.
> 
> Previous behaviour was that module loading failed if no appropriate
> CPU was found. Now we get
> 
>  [  131.717212] WARNING: at fs/sysfs/group.c:138 mc_device_remove+0x5f/0x70 [microcode]()
>  [  131.717218] Hardware name: 01972NG
>  [  131.717223] sysfs group ffffffffa00013d0 not found for kobject 'cpu0'
>  [  131.717228] Modules linked in: snd_hda_codec_hdmi snd_hda_codec_conexant snd_hda_intel
>                 btusb snd_hda_codec bluetooth thinkpad_acpi rfkill microcode(-) [last unloaded: cfg80211]
>  [  131.717254] Pid: 4560, comm: modprobe Not tainted 3.4.0-rc2-00002-g258f742 #5
>  [  131.717260] Call Trace:
>  [  131.717277]  [<ffffffff8103113b>] ? warn_slowpath_common+0x7b/0xc0
>  [  131.717287]  [<ffffffff81031235>] ? warn_slowpath_fmt+0x45/0x50
>  [  131.717300]  [<ffffffff81120e74>] ? sysfs_remove_group+0x34/0x120
>  [  131.717311]  [<ffffffffa00000ef>] ? mc_device_remove+0x5f/0x70 [microcode]
>  [  131.717325]  [<ffffffff81331eb9>] ? subsys_interface_unregister+0x69/0xa0
>  [  131.717336]  [<ffffffff81563526>] ? mutex_lock+0x16/0x40
>  [  131.717346]  [<ffffffffa0000c3e>] ? microcode_exit+0x50/0x92 [microcode]
>  [  131.717357]  [<ffffffff8107051d>] ? sys_delete_module+0x16d/0x260
>  [  131.717369]  [<ffffffff810a0065>] ? wait_iff_congested+0x45/0x110
>  [  131.717379]  [<ffffffff815656af>] ? page_fault+0x1f/0x30
>  [  131.717389]  [<ffffffff81565ba2>] ? system_call_fastpath+0x16/0x1b
> 
> 
> after loading the driver on an unsupported CPU and the subsequent
> attempt to unload the driver.

That's not nice, but why is the driver getting loaded for a CPU that it
doesn't control?  Startup scripts?

It's just a "warning", everything else still works properly, right?

Patches to fix this up are always gladly accepted :)

thanks,

greg k-h