[ 093/167] [PATCH] x86, microcode: Fix sysfs warning during module unload onunsupported CPUs

From: Ben Hutchings
Date: Wed May 09 2012 - 01:59:54 EST

3.2-stable review patch. If anyone has any objections, please let me know.


From: Andreas Herrmann <andreas.herrmann3@xxxxxxx>

commit a956bd6f8583326b18348ab1452b4686778f785d upstream.

Loading the microcode driver on an unsupported CPU and subsequently
unloading the driver causes

WARNING: at fs/sysfs/group.c:138 mc_device_remove+0x5f/0x70 [microcode]()
Hardware name: 01972NG
sysfs group ffffffffa00013d0 not found for kobject 'cpu0'
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]
Pid: 4560, comm: modprobe Not tainted 3.4.0-rc2-00002-g258f742 #5
Call Trace:
[<ffffffff8103113b>] ? warn_slowpath_common+0x7b/0xc0
[<ffffffff81031235>] ? warn_slowpath_fmt+0x45/0x50
[<ffffffff81120e74>] ? sysfs_remove_group+0x34/0x120
[<ffffffffa00000ef>] ? mc_device_remove+0x5f/0x70 [microcode]
[<ffffffff81331eb9>] ? subsys_interface_unregister+0x69/0xa0
[<ffffffff81563526>] ? mutex_lock+0x16/0x40
[<ffffffffa0000c3e>] ? microcode_exit+0x50/0x92 [microcode]
[<ffffffff8107051d>] ? sys_delete_module+0x16d/0x260
[<ffffffff810a0065>] ? wait_iff_congested+0x45/0x110
[<ffffffff815656af>] ? page_fault+0x1f/0x30
[<ffffffff81565ba2>] ? system_call_fastpath+0x16/0x1b

on recent kernels.

This is due to commit 8a25a2fd126c ("cpu: convert 'cpu' and
'machinecheck' sysdev_class to a regular subsystem") which renders
commit 6c53cbfced04 ("x86, microcode: Correct sysdev_add error path")

See http://marc.info/?l=linux-kernel&m=133416246406478

Avoid above warning by restoring the old driver behaviour before
6c53cbfced04 ("x86, microcode: Correct sysdev_add error path").

Cc: Tigran Aivazian <tigran@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andreas Herrmann <andreas.herrmann3@xxxxxxx>
Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20120411163849.GE4794@xxxxxxxxxxxxxxxx
Signed-off-by: Borislav Petkov <borislav.petkov@xxxxxxx>
[bwh: Backported to 3.2: deleted line uses sys_dev, not dev]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
arch/x86/kernel/microcode_core.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

--- a/arch/x86/kernel/microcode_core.c
+++ b/arch/x86/kernel/microcode_core.c
@@ -419,10 +419,8 @@ static int mc_device_add(struct device *dev, struct subsys_interface *sif)
if (err)
return err;

- if (microcode_init_cpu(cpu) == UCODE_ERROR) {
- sysfs_remove_group(&sys_dev->kobj, &mc_attr_group);
+ if (microcode_init_cpu(cpu) == UCODE_ERROR)
return -EINVAL;
- }

return err;

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