Locking the output queue prior to TX is needed on OSA devices,
to synchronize against a packing flush from the TX completion code
(via qeth_check_outbound_queue()).
But send_packet_fast() is only used for IQDs, which don't do packing.
So remove the locking, and apply some easy cleanups.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

HiperSockets allow configuring so called VNIC Characteristics (VNICC)
that influence how the underlying hardware handles packets. For VNICCs,
additional commands for getting and setting timeouts are available.
Currently, the learning VNICC uses these commands.

* Learning VNICC: If learning is enabled on a qeth device, the device
  learns the source MAC addresses of outgoing packets and incoming
  packets to those learned MAC addresses are received.

For learning, the timeout specifies the idle period in seconds, after
which the underlying hardware removes a learned MAC address again.

This patch adds support for the IPA commands that are required to get
and set the current timeout values for the learning VNIC characteristic.
Also, it introduces the sysfs interface that allows users to configure
the timeout.
Signed-off-by: NHans Wippel <hwippel@linux.vnet.ibm.com>
Reviewed-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

HiperSocket devices allow enabling and disabling so called VNIC
Characteristics (VNICC) that influence how the underlying hardware
handles packets. These VNICCs are:

* Flooding VNICC: Flooding allows specifying if packets to unknown
  destination MAC addresses are received by the qeth device.

* Multicast flooding VNICC: Multicast flooding allows specifying if
  packets to multicast MAC addresses are received by the qeth device.

* Learning VNICC: If learning is enabled on a qeth device, the device
  learns the source MAC addresses of outgoing packets and incoming
  packets to those learned MAC addresses are received.

* Takeover setvmac VNICC: If takeover setvmac is configured on a qeth
  device, the MAC address of this device can be configured on a
  different qeth device with the setvmac IPA command.

* Takeover by learning VNICC: If takeover learning is enabled on a qeth
  device, the MAC address of this device can be learned (learning VNICC)
  on a different qeth device.

* BridgePort invisible VNICC: If BridgePort invisible is enabled on a
  qeth device, (1) packets from this device are not sent to a BridgePort
  enabled qeth device and (2) packets coming from a BridgePort enabled
  qeth device are not received by this device.

* Receive broadcast VNICC: Receive broadcast allows configuring if a
  qeth device receives packets with the broadcast destination MAC
  address.

This patch adds support for the IPA commands that are required to enable
and disable these VNIC characteristics on qeth devices. As a
prerequisite, it also adds the query commands IPA command.

The query commands IPA command allows requesting the supported commands
for each characteristic from the underlying hardware.

Additionally, this patch provides users with a sysfs user interface to
enable/disable the VNICCs mentioned above.
Signed-off-by: NHans Wippel <hwippel@linux.vnet.ibm.com>
Reviewed-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

VNIC Characteristics (VNICC) are features of HiperSockets that define
how packets are handled by the underlying network hardware. For example,
if the VNICC flooding is configured on a qeth device, ethernet frames to
unknown destination MAC addresses are received.

Currently, there is support for seven VNICCs: flooding, multicast
flooding, receive broadcast, learning, takeover learning, takeover
setvmac, bridge invisible. Also, six IPA commands exist for configuring
VNICCs on a qeth device: query characteristics, query commands, enable
characteristic, disable characteristic, set timeout, get timeout.

This patch adds the basic code infrastructure for VNICC support to qeth.
It allows querying VNICC support from the underlying hardware. To this
end, it adds:

* basic message formats for IPA commands
* basic data structures
* basic error handling
* query characteristics IPA command support

The query characteristics IPA command allows requesting the currently
supported and currently enabled VNIC characteristics from the underlying
hardware.

Support for the other IPA commands and for the configuration of VNICCs
is added in follow-up patches together with the respective user
interface functions.
Signed-off-by: NHans Wippel <hwippel@linux.vnet.ibm.com>
Reviewed-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Taking a full copy via skb_realloc_headroom() on every xmit is overkill
and wastes CPU time; all we actually need is to push on the qeth_hdr.
So rework the L2 OSA TX path to avoid the copy.
Minor complications arise because struct qeth_hdr must not cross a page
boundary. So add a new helper qeth_push_hdr() that catches this, and
falls back to the hdr cache that we already use for IQDs.

This change uncovered that qeth's TX completion takes rather long.
Now that we no longer free the original skb straight away and thus call
skb->destructor later than before, throughput regresses significantly.
For now, restore old behaviour by adding an explicit skb_orphan(),
and a big TODO to improve the TX completion time.
Tested-by: NNils Hoppmann <niho@de.ibm.com>
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

For TSO we need to skip the skb's qeth/IP/TCP headers when mapping
it into buffer elements. Instead of (mis)using skb_pull(), pass a
corresponding offset to fill_buffer() like we already do for IQDs.

No actual change in the resulting TSO buffers.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The TSO code already calculates the length of its header element,
no need to duplicate this in the low-level code again.

Use this opportunity to make hd_len unsigned, and for TSO match
its calculation to what tso_fill_header() does.

No functional change.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Replace some open-coded parts with their proper API calls.

Also remove two skb_[re]set_mac_header() calls in the L2
xmit paths that are clearly no longer required, since at least
commit 6d1ccff6 ("net: reset mac header in dev_start_xmit()").
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Acked-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

For some xmit paths we pass down a data offset to qeth_fill_buffer(),
to indicate that the first k bytes of the skb should be skipped when
mapping it into buffer elements.
Commit acd9776b ("s390/qeth: no ETH header for outbound AF_IUCV")
recently switched the offset for the IUCV-over-HiperSockets path
from 0 to ETH_HLEN, and now we have

	device	offset
	OSA	= 0
	IQD	> 0

for all xmit paths.

OSA would previously pass down -1 from do_send_packet(), to distinguish
between 1) OSA and 2) IQD with offset 0. That's no longer needed now,
so have it pass 0, make the offset unsigned and clean up how we apply
the offset in __qeth_fill_buffer().

No change of behaviour for any of our current xmit paths.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Acked-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When a s390 guest runs on a z/VM host that's part of a SSI cluster,
it can be migrated to a different host. In this case, the MAC address
it originally obtained on the old host may be re-assigned to a new
guest. This would result in address conflicts between the two guests.

When running as z/VM guest, use the diag26c MAC Service to obtain
a hypervisor-managed MAC address. The MAC Service is SSI-aware, and
won't re-assign the address after the guest is migrated to a new host.

This patch adds support for the z/VM MAC Service on L2 devices.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Acked-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

qeth currently supports early setup for OSM and OSN devices.
This patch adds early setup support for z/VM HiperSockets,
since they can only be coupled to L3 networks.

Based on an initial version by Dmitriy Lakhvich.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

commit b4d72c08 ("qeth: bridgeport support - basic control")
broke the support for OSM and OSN devices as follows:

As OSM and OSN are L2 only, qeth_core_probe_device() does an early
setup by loading the l2 discipline and calling qeth_l2_probe_device().
In this context, adding the l2-specific bridgeport sysfs attributes
via qeth_l2_create_device_attributes() hits a BUG_ON in fs/sysfs/group.c,
since the basic sysfs infrastructure for the device hasn't been
established yet.

Note that OSN actually has its own unique sysfs attributes
(qeth_osn_devtype), so the additional attributes shouldn't be created
at all.
For OSM, add a new qeth_l2_devtype that contains all the common
and l2-specific sysfs attributes.
When qeth_core_probe_device() does early setup for OSM or OSN, assign
the corresponding devtype so that the ccwgroup probe code creates the
full set of sysfs attributes.
This allows us to skip qeth_l2_create_device_attributes() in case
of an early setup.

Any device that can't do early setup will initially have only the
generic sysfs attributes, and when it's probed later
qeth_l2_probe_device() adds the l2-specific attributes.

If an early-setup device is removed (by calling ccwgroup_ungroup()),
device_unregister() will - using the devtype - delete the
l2-specific attributes before qeth_l2_remove_device() is called.
So make sure to not remove them twice.

What complicates the issue is that qeth_l2_probe_device() and
qeth_l2_remove_device() is also called on a device when its
layer2 attribute changes (ie. its layer mode is switched).
For early-setup devices this wouldn't work properly - we wouldn't
remove the l2-specific attributes when switching to L3.
But switching the layer mode doesn't actually make any sense;
we already decided that the device can only operate in L2!
So just refuse to switch the layer mode on such devices. Note that
OSN doesn't have a layer2 attribute, so we only need to special-case
OSM.

Based on an initial patch by Ursula Braun.

Fixes: b4d72c08 ("qeth: bridgeport support - basic control")
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

prepare() and complete() are not implemented by any discipline, so just
drop all the indirection.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Reviewed-by: NHans Wippel <hwippel@linux.vnet.ibm.com>
Reviewed-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

get_settings() is deprecated and lacks support for higher link
speeds, so implement get_link_ksettings() instead.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Reviewed-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

1. a buffer has 16 is_header flags, because that's its # of elements
2. replace the last occurrence of QETH_HEADER_SIZE, and remove it
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Acked-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

'elements_needed' is not used in qeth_do_send_packet_fast(),
so consequently remove it.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Acked-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Duplicated code.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Acked-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Identical code, we just need to call a layer-specific hook
to process any received buffer.

qeth_buffer_reclaim_work() is shuffled around to avoid a
forward declaration for qeth_queue_input_buffer().
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Acked-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There's a number of layer-independent ioctls that we can handle
in core, and reduce code duplication. For layer-specific ioctls,
add a do_ioctl() discipline hook.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Acked-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Avoid endianness warnings reported by sparse by (1) using endianness
conversions for assigning and using network packet fields, and (2)
removing unnecessary endianness conversions from qeth_l3_rebuild_skb. No
functional changes.
Signed-off-by: NHans Wippel <hwippel@linux.vnet.ibm.com>
Signed-off-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

1. options.add_hhlen is set but never used, drop it
2. clean up no longer required forward declarations
3. delete all sorts of unused defines
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Reviewed-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

qeth_qdio_output_handler() is the only caller of
qeth_handle_send_error() and doesn't care about the return value.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Reviewed-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Depending on the device type, hard_start_xmit() builds different output
buffer formats. For instance with HiperSockets, on both L2 and L3 we
strip the ETH header from the skb - L3 doesn't need it, and L2 carries
it in the buffer's header element.
For this, we pass data_offset = ETH_HLEN all the way down to
__qeth_fill_buffer(), where skb->data is then adjusted accordingly.
But the initial size calculation still considers the *full* skb length
(including the ETH header). So qeth_get_elements_no() can erroneously
reject a skb as too big, even though it would actually fit into an
output buffer once the ETH header has been trimmed off later.

Fix this by passing an additional offset to qeth_get_elements_no(),
that indicates where in the skb the on-wire data actually begins.
Since the current code uses data_offset=-1 for some special handling
on OSA, we need to clamp data_offset to 0...

On HiperSockets this helps when sending ~MTU-size skbs with weird page
alignment. No change for OSA or AF_IUCV.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

STARTLAN needs to be the first IPA command after MPC initialization
completes.
So move the qeth_send_startlan() call from the layer disciplines
into the core path, right after the MPC handshake.
While at it, replace the magic LAN OFFLINE return code
with the existing enum.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Reviewed-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Remove unused define QETH_IP_HEADER_SIZE.
Signed-off-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Reviewed-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Acked-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Rework the RX/TX checksum offloading command sequence to use
the provided function call back mechanims to return card
data to the device driver.
Signed-off-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Reviewed-by: NJulian Wiedmann <jwi@linux.vnet.ibm.com>
Reviewed-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

After device recovery, only a basic set of network device features is
enabled on the device. If features like checksum offloading or TSO were
enabled by the user before the recovery, this results in a mismatch
between the network device features, that the kernel assumes to be
enabled on the device, and the features actually enabled on the device.

This patch tries to restore previously set features, that require
changes on the device, after the recovery of a device. In case of an
error, the network device's features are changed to contain only the
features that are actually turned on.
Signed-off-by: NHans Wippel <hwippel@linux.vnet.ibm.com>
Signed-off-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch introduces a common set of fix_features and set_features
functions for layer 2 and layer 3. The RX, TX and TSO offload
functionality on the OSA card is enabled using ethtool at user's
request and not at device initialization as done before.

For layer 3 the RX checksum offloading is disabled at device
initialization time.
Signed-off-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In layer3 mode of the qeth driver, multicast IP addresses
from struct net_device and other type of IP addresses
from other sources require mapping to the OSA-card.
This patch simplifies the IP address mapping logic, and changes imple-
mentation of ndo_set_rx_mode callback and ip notifier events.
Addresses are stored in private hashtables instead of lists now.
It allows hardware registration/removal for new/deleted multicast
addresses only.
Signed-off-by: NLakhvich Dmitriy <ldmitriy@ru.ibm.com>
Signed-off-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Reviewed-by: NEvgeny Cherkashin <Eugene.Crosser@ru.ibm.com>
Reviewed-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When skb data touches too many pages, skb_linearize() is called
opportunistically in the hope that less pages will be required
for a big linear buffer than for multiple fragments. This patch
intoduces a separate counter in ethtool statistics structure
representing _failed_ linearization attempts.
Signed-off-by: NEugene Crosser <Eugene.Crosser@ru.ibm.com>
Signed-off-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Reviewed-by: NLakhvich Dmitriy <ldmitriy@ru.ibm.com>
Reviewed-by: NThomas Richter <tmricht@de.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Make conditions under which TSO is activated more stringent.
Make calculation of SBALEs required for the skb more accurate.
Signed-off-by: NEugene Crosser <Eugene.Crosser@ru.ibm.com>
Signed-off-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Rewrite the functions that calculate the required number of buffer
elements needed to represent SKB data, to make them hopefully more
comprehensible. Plus a few cleanups.
Signed-off-by: NEugene Crosser <Eugene.Crosser@ru.ibm.com>
Signed-off-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There have been 2 identical versions of function
qeth_get_setassparms_cmd() for layer 2 and layer 3.
Remove the layer 3 function qeth_l3_get_setassparms_cmd()
and call the common one named qeth_get_setassparms_cmd()
located in qeth_core_main.c
Signed-off-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Reviewed-by: NEugene Crosser <Eugene.Crosser@ru.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In layer2 mode of the qeth driver, MAC address lists
from struct net_device require mapping to the OSA-card.
The existing implementation is inefficient for lists with
more than several MAC addresses, since for every
ndo_set_rx_mode callback it removes all MAC addresses first,
and then registers the current MAC address list.
This patch changes implementation of ndo_set_rx_mode callback
in qeth, only performing hardware registration/removal for
new/deleted addresses. To shorten lookup of MAC addresses
registered addresses are kept in a hashtable instead of a
linear list.
Signed-off-by: NLakhvich Dmitriy <ldmitriy@ru.ibm.com>
Signed-off-by: NUrsula Braun <ursula.braun@de.ibm.com>
Reviewed-by: NEugene Crosser <Eugene.Crosser@ru.ibm.com>
Reviewed-by: NThomas Richter <tmricht@de.ibm.com>
Tested-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Checksum offloading for send and receive is already
supported for layer 3 (IP layer). This patch
adds support for RX and TX hardware checksum offloading
for layer 2 (MAC layer). The hardware calculates the checksum
for IP UDP and TCP packets.

This patch moves the hardware checksum offloading setup
to the set of common functions in qeth_core_main.c.
Layer 2 and layer 3 now simply call the same common functions.

Also note that TX checksum offloading is always enabled.
The device driver relies on the TCP/IP stack to make use of
this feature.
Signed-off-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: NUrsula Braun <ursula.braun@de.ibm.com>
Reviewed-by: NEugene Crosser <Eugene.Crosser@ru.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

An OSA-Express port name was required to identify a shared OSA port.
All operating system instances that shared the port had to use the
same port name. This requirement no longer applies.
Signed-off-by: NUrsula Braun <ursula.braun@de.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

OSA and HiperSocket devices do not support promiscuous mode proper,
but they support "BRIDGE PORT" mode that is functionally similar.
This update introduces sysfs attribute that, when set, makes the driver
try to "reflect" setting and resetting of the IFF_PROMISC flag on the
interface into setting and resetting PRIMARY or SECONDARY bridge port
role on the underlying OSA or HiperSocket device.
Reviewed-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: NEugene Crosser <Eugene.Crosser@ru.ibm.com>
Signed-off-by: NUrsula Braun <ursula.braun@de.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The member irq_tasklet in the qeth_channel structure
is not referenced anymore and is removed from the
structure.
Signed-off-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: NUrsula Braun <ursula.braun@de.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch makes some global functions static and removes
the prototypes from the header file.
Also function qeth_query_card_info is not exported anymore,
there is no external user for it, this function should never
have been exported in the first place.
Signed-off-by: NThomas Richter <tmricht@linux.vnet.ibm.com>
Signed-off-by: NFrank Blaschka <blaschka@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When qeth device is queried for ethtool data, hardware operation
is performed to extract the necessary information from the card.
If the card is not online at the moment (e.g. it is undergoing
recovery), this operation produces undesired effects like
temporarily freezing the system. This patch prevents execution
of the hardware query operation when the card is not online.
In such case, ioctl() operation returns error with errno ENODEV.
Reviewed-by: NUrsula Braun <ursula.braun@de.ibm.com>
Signed-off-by: NEugene Crosser <Eugene.Crosser@ru.ibm.com>
Signed-off-by: NFrank Blaschka <blaschka@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>