Got the following oops just before reboot:

Unable to handle kernel NULL pointer dereference at virtual address 00000000
[<8028d300>] (__list_del_entry+0x44/0xac)
[<802e3320>] (__fw_load_abort.part.13+0x1c/0x50)
[<802e337c>] (fw_shutdown_notify+0x28/0x50)
[<80034f80>] (notifier_call_chain.isra.1+0x5c/0x9c)
[<800350ec>] (__blocking_notifier_call_chain+0x44/0x58)
[<80035114>] (blocking_notifier_call_chain+0x14/0x18)
[<80035d64>] (kernel_restart_prepare+0x14/0x38)
[<80035d94>] (kernel_restart+0xc/0x50)

The following race condition triggers here:

  _request_firmware_load()
  device_create_file(...)
  kobject_uevent(...)
  (schedule)
                                       (resume)
                                       firmware_loading_store(1)
                                       firmware_loading_store(0)
                                       list_del_init(&buf->pending_list)
                                       (schedule)
  (resume)
  list_add(&buf->pending_list, &pending_fw_head);
  wait_for_completion(&buf->completion);

causing an oops later when walking pending_list after the firmware has
been released.

The proposed fix is to move the list_add() before sysfs attribute
creation.
Signed-off-by: NMaxime Bizon <mbizon@freebox.fr>
Acked-by: NMing Lei <ming.lei@canonical.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Introduce help macro to_memory_block to hide the conversion(device-->memory_block),
just clean up.
Reviewed-by: NYasuaki Ishimatsu  <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: NGu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The bus_attrs field of struct bus_type is going away soon, dev_groups
should be used instead.  This converts the RBD bus code to use the
correct field.

Cc: Yehuda Sadeh <yehuda@inktank.com>
Cc: Sage Weil <sage@inktank.com>
Acked-by: NAlex Elder <elder@linaro.org>
Cc: <ceph-devel@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The dcdbas code was "hand rolling" a binary attribute group, which the
driver core now supports automatically.  So remove the "create the files
by hand" logic, and just set the proper field in the attribute group
structure, saving lots of code and headache.

Cc: Doug Warzecha <Douglas_Warzecha@dell.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

--

 Doug, I can take this through my driver-core tree if you don't object.

 drivers/firmware/dcdbas.c |   19 ++-----------------
 1 file changed, 2 insertions(+), 17 deletions(-)

This is needed to fix the build on sh systems.
Reported-by: Nkbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The dev_attrs field of struct bus_type is going away soon, dev_groups
should be used instead.  This converts the HID bus code to use
the correct field.
Acked-by: NJiri Kosina <jkosina@suse.cz>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The drv_attrs field of struct bus_type is going away soon, drv_groups
should be used instead.  This converts the serio bus code to use the
correct field.
Acked-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The drv_attrs field of struct bus_type is going away soon, drv_groups
should be used instead.  This converts the gameport bus code to use the
correct field.

Acked: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Use __ATTR_RW() instead of __ATTR() to make it more obvious what the
type of attribute is being created.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Use DEVICE_ATTR_RO() instead of a "raw" __ATTR macro, making it easier
to audit exactly what is going on with the sysfs files.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

There are two bus attributes that can better be defined using
DRIVER_ATTR_WO(), so convert them to the new macro, making it easier to
audit attribute permissions.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The dev_attrs field of struct bus_type is going away soon, dev_groups
should be used instead.  This converts the platform bus code to use
the correct field.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The dev_attrs field of struct bus_type is going away soon, dev_groups
should be used instead.  This converts the MEI bus code to use
the correct field.
Acked-by: NTomas Winkler <tomas.winkler@intel.com>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The drv_attrs field of struct bus_type is going away soon, drv_groups
should be used instead.  This converts the USB serial bus code to use
the correct field.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This moves the sysfs file creation/removal to the w1 core by using the
.groups field, saving code in the slave driver.
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Cc: Alexander Stein <alexander.stein@informatik.tu-chemnitz.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This moves the sysfs file creation/removal to the w1 core by using the
.groups field, saving code in the slave driver.
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Cc: Alexander Stein <alexander.stein@informatik.tu-chemnitz.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This moves the sysfs file creation/removal to the w1 core by using the
.groups field, saving code in the slave driver.
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Cc: Alexander Stein <alexander.stein@informatik.tu-chemnitz.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This moves the sysfs file creation/removal to the w1 core by using the
.groups field, saving code in the slave driver.
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Cc: Alexander Stein <alexander.stein@informatik.tu-chemnitz.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This moves the sysfs file creation/removal to the w1 core by using the
.groups field, saving code in the slave driver.
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Cc: Alexander Stein <alexander.stein@informatik.tu-chemnitz.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This moves the sysfs file creation/removal to the w1 core by using the
.groups field, saving code in the slave driver.
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Cc: Alexander Stein <alexander.stein@informatik.tu-chemnitz.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This moves the sysfs file creation/removal to the w1 core by using the
.groups field, saving code in the slave driver.
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Cc: Alexander Stein <alexander.stein@informatik.tu-chemnitz.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This moves the sysfs file creation/removal to the w1 core by using the
.groups field, saving code in the slave driver.
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Stein <alexander.stein@informatik.tu-chemnitz.de>
Cc: Mariusz Bialonczyk <manio@skyboo.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This moves the sysfs file creation/removal to the w1 core by using the
.groups field, saving code in the slave driver.
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Cc: Jean-Francois Dagenais <jeff.dagenais@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Stein <alexander.stein@informatik.tu-chemnitz.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This moves the sysfs file creation/removal to the w1 core by using the
.groups field, saving code in the slave driver.
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Cc: David Stevenson <david@avoncliff.com>
Cc: Alexander Stein <alexander.stein@informatik.tu-chemnitz.de>
Cc: Michael Arndt <michael@scriptkiller.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This lets w1 slave drivers declare an attribute group, and not have to
create/destroy sysfs files directly.  All w1 slave drivers will be fixed
to use this field up in follow-on patches to this one.
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

As we have 2 sysfs files for the w1 slave devices, let the driver core
create / destroy them automatically by setting the default attribute
group for them, saving code and housekeeping logic.
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

W1 slave sysfs files are created _after_ userspace is notified that the
device has been added to the system.  Fix that race by moving the
creation/remove of the files to the bus notifier that is there for doing
this type of thing.
Acked-by: NEvgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Gotta love a macro that doesn't reduce the typing you have to do.

Also, only the driver core, and one network driver uses this.  The
driver core functions will be going away soon, and I'll convert the
network driver soon to not need this as well, so delete it for now
before anyone else gets some bright ideas and wants to use it.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

No need to call sysfs_bin_attr_init, as the attribute is not dynamically
created.  Also, we renamed the attribute, so this one isn't even valid
anymore.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Cc: Len Brown <lenb@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

These functions are being open-coded in 3 different places in the driver
core, and other driver subsystems will want to start doing this as well,
so move it to the sysfs core to keep it all in one place, where we know
it is written properly.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

There are two ways to set the online/offline state for a memory block:
echo 0|1 > online and echo online|online_kernel|online_movable|offline >
state.

The state attribute can online a memory block with extra data, the
"online type", where the online attribute uses a default online type of
ONLINE_KEEP, same as echo online > state.

Currently there is a state_mutex that provides consistency between the
memory block state and the underlying memory.

The problem is that this code does a lot of things that the common
device layer can do for us, such as the serialization of the
online/offline handlers using the device lock, setting the dev->offline
field, and calling kobject_uevent().

This patch refactors the online/offline code to allow the common
device_[online|offline] functions to be used.  The result is a simpler
and more common code path for the two state setting mechanisms.  It also
removes the state_mutex from the struct memory_block as the memory block
device lock provides the state consistency.

No functional change is intended by this patch.
Signed-off-by: NSeth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Right now memory_dev_init() maintains the memory block pointer
between iterations of add_memory_section().  This is nasty.

This patch refactors add_memory_section() to become add_memory_block().
The refactoring pulls the section scanning out of memory_dev_init()
and simplifies the signature.
Signed-off-by: NSeth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The path through add_memory_section() when the memory block already
exists uses flawed refcounting logic.  A get_device() is done on a
memory block using a pointer that might not be valid as we dropped
our previous reference and didn't obtain a new reference in the
proper way.

Lets stop pretending and just remove the get/put.  The
mem_sysfs_mutex, which we hold over the entire init loop now, will
prevent the memory blocks from disappearing from under us.
Signed-off-by: NSeth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Now that add_memory_section() is only called from boot time, reduce
the logic and remove the enum.
Signed-off-by: NSeth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

add_memory_section() is currently called from both boot time and run
time via hotplug and there is a lot of nastiness to allow for shared
code including an enum parameter to convey the calling context to
add_memory_section().

This patch is the first step in breaking up the messy code sharing by
pulling the hotplug path for add_memory_section() directly into
register_new_memory().
Signed-off-by: NSeth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Use the [get|put]_device functions for ref'ing the memory block device
rather than the kobject functions which should be hidden away by the
device layer.
Signed-off-by: NSeth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The error variable is not needed.
Signed-off-by: NSeth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

There is no point in releasing the mutex for each section that is added
during boot time.  Just hold it over the entire initialization loop.
Signed-off-by: NSeth Jennings <sjenning@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Attribute groups now can handle binary sysfs attributes, so clean up the
code here by using a binary attribute array.  This saves us the extra
call to create the binary attribute at saves 6 lines overall.

Cc: Len Brown <lenb@kernel.org>
Acked-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

--
 I can take this in my driver-core tree if someone from ACPI acks it,
 otherwise, feel free to take it through the ACPI trees instead, just
 let me know.

 drivers/acpi/bgrt.c |   26 ++++++++++----------------
 1 file changed, 10 insertions(+), 16 deletions(-)

Now that attribute groups support binary attributes, use them instead of
the dev_bin_attrs field in struct class, as that is going away soon.

Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Stefan Achatz <erazor_de@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>