In the latest revision of the hardware, if a packet is spanning
across multiple BDs then only VLD bit and current data size info
is valid in each BD, and rest of the information is only valid
in the last BD of the packet. In such case we should make sure
we are fetching RX packet size from the first descriptor and
information like VLAN should be fetched from last BD.
Signed-off-by: NPeng Li <lipeng321@huawei.com>
Reviewed-by: NYisen Zhuang <yisen.zhuang@huawei.com>
Signed-off-by: NSalil Mehta <salil.mehta@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

SIMCOM are reusing a single device ID for many (all of their?)
different modems, based on different chipsets and firmwares. Newer
Qualcomm chipset generations require setting DTR to wake the QMI
function.  The SIM7600E modem is using such a chipset, making it
fail to work with this driver despite the device ID match.

Fix by unconditionally enabling the SET_DTR quirk for all SIMCOM
modems using this specific device ID.  This is similar to what
we already have done for another case of device IDs recycled over
multiple chipset generations: 14cf4a77 ("drivers: net: usb:
qmi_wwan: add QMI_QUIRK_SET_DTR for Telit PID 0x1201")

Initial testing on an older SIM7100 modem shows no immediate side
effects.
Reported-by: NSebastian Sjoholm <sebastian.sjoholm@gmail.com>
Cc: Reinhard Speyerer <rspmn@arcor.de>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Manage dwmac-4.20a version from synopsys
Signed-off-by: NChristophe Roullier <christophe.roullier@st.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Glue codes to support stm32mp157c device and stay
compatible with stm32 mcu familly
Signed-off-by: NChristophe Roullier <christophe.roullier@st.com>
Acked-by: NAlexandre TORGUE <alexandre.torgue@st.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Global variable gfar_phc_index was used to get and store
phc index through gianfar_ptp driver. However gianfar_ptp
had been renamed as ptp_qoriq for QorIQ common PTP driver.
This gfar_phc_index doesn't work any more, and the phc index
is stored in drvdata now. This patch is to support getting
phc index through ptp_qoriq drvdata.
Signed-off-by: NYangbo Lu <yangbo.lu@nxp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

gianfar_ptp was the PTP clock driver for 1588 timer
module of Freescale QorIQ eTSEC (Enhanced Three-Speed
Ethernet Controllers) platforms. Actually QorIQ DPAA
(Data Path Acceleration Architecture) platforms is
also using the same 1588 timer module in hardware.

This patch is to rework gianfar_ptp as QorIQ common
PTP driver to support both DPAA and eTSEC. Moved
gianfar_ptp.c to drivers/ptp/, renamed it as
ptp_qoriq.c, and renamed many variables. There were
not any function changes.
Signed-off-by: NYangbo Lu <yangbo.lu@nxp.com>
Acked-by: NRichard Cochran <richardcochran@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fixup the checksum for CHECKSUM_COMPLETE when pulling skbs on RX path.
Otherwise we get splats when tc mirred is used to redirect packets to ifb.

Before fix:

nic: hw csum failure
Signed-off-by: NJon Maxwell <jmaxwell37@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add RTL8211B suspend / resume callbacks.
Signed-off-by: NHeiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch enables virtio_net to switch over to a VF datapath when STANDBY
feature is enabled and a VF netdev is present with the same MAC address.
It allows live migration of a VM with a direct attached VF without the need
to setup a bond/team between a VF and virtio net device in the guest.

It uses the API that is exported by the net_failover driver to create and
and destroy a master failover netdev. When STANDBY feature is enabled, an
additional netdev(failover netdev) is created that acts as a master device
and tracks the state of the 2 lower netdevs. The original virtio_net netdev
is marked as 'standby' netdev and a passthru device with the same MAC is
registered as 'primary' netdev.

The hypervisor needs to unplug the VF device from the guest on the source
host and reset the MAC filter of the VF to initiate failover of datapath
to virtio before starting the migration. After the migration is completed,
the destination hypervisor sets the MAC filter on the VF and plugs it back
to the guest to switch over to VF datapath.

This patch is based on the discussion initiated by Jesse on this thread.
https://marc.info/?l=linux-virtualization&m=151189725224231&w=2Signed-off-by: NSridhar Samudrala <sridhar.samudrala@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This feature bit can be used by hypervisor to indicate virtio_net device to
act as a standby for another device with the same MAC address.

VIRTIO_NET_F_STANDBY is defined as bit 62 as it is a device feature bit.
Signed-off-by: NSridhar Samudrala <sridhar.samudrala@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The net_failover driver provides an automated failover mechanism via APIs
to create and destroy a failover master netdev and manages a primary and
standby slave netdevs that get registered via the generic failover
infrastructure.

The failover netdev acts a master device and controls 2 slave devices. The
original paravirtual interface gets registered as 'standby' slave netdev and
a passthru/vf device with the same MAC gets registered as 'primary' slave
netdev. Both 'standby' and 'failover' netdevs are associated with the same
'pci' device. The user accesses the network interface via 'failover' netdev.
The 'failover' netdev chooses 'primary' netdev as default for transmits when
it is available with link up and running.

This can be used by paravirtual drivers to enable an alternate low latency
datapath. It also enables hypervisor controlled live migration of a VM with
direct attached VF by failing over to the paravirtual datapath when the VF
is unplugged.
Signed-off-by: NSridhar Samudrala <sridhar.samudrala@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use the registration/notification framework supported by the generic
failover infrastructure.
Signed-off-by: NSridhar Samudrala <sridhar.samudrala@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

SCTP sockets originated in a VRF can improve their performance if CRC32c
computation is delegated to underlying devices: update device features,
setting NETIF_F_SCTP_CRC. Iterating the following command in the topology
proposed with [1],

 # ip vrf exec vrf-h2 netperf -H 192.0.2.1 -t SCTP_STREAM -- -m 10K

the measured throughput in Mbit/s improved from 2395 ± 1% to 2720 ± 1%.

[1] https://www.spinics.net/lists/netdev/msg486007.htmlSigned-off-by: NDavide Caratti <dcaratti@redhat.com>
Reviewed-by: NMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Some drivers, such as DWC EQOS on Tegra, need to perform operations that
can sleep under this lock (clk_set_rate() in tegra_eqos_fix_speed()) for
proper operation. Since there is no need for this lock to be a spinlock,
convert it to a mutex instead.

Fixes: e6ea2d16 ("net: stmmac: dwc-qos: Add Tegra186 support")
Reported-by: NJon Hunter <jonathanh@nvidia.com>
Signed-off-by: NThierry Reding <treding@nvidia.com>
Tested-by: NBhadram Varka <vbhadram@nvidia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Tx-timeout mostly happens due to some issue in the device. In such cases,
debug dump would be helpful for identifying the cause of the issue.
This patch adds support to spill debug data during the Tx timeout. Here
bnx2x_panic_dump() API is used instead of bnx2x_panic(), since we still
want to allow the Tx-timeout recovery a chance to succeed.

Changes from previous version:
-------------------------------
v2: Fixed a coding error.

Please consider applying this to "net-next".
Signed-off-by: NSudarsana Reddy Kalluru <Sudarsana.Kalluru@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Remove redundant debug prints from phy_read/write since we can trace those
calls through trace events. Enhance dynamic debug prints to print arguments
which helps figuring how what is going on at the driver level with higher level
configuration interfaces.
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The call to free_netdev() in __rtl8139_cleanup_dev() clears the network device
napi list, and explicit calls to netif_napi_del() are unnecessary.
Signed-off-by: NBo Chen <chenbo@pdx.edu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In its current state, the driver will handle backing device
login in a loop for a certain number of retries while the
device returns a partial success, indicating that the driver
may need to try again using a smaller number of resources.

The variable it checks to continue retrying may change
over the course of operations, resulting in reallocation
of resources but exits without sending the login attempt.
Guard against this by introducing a boolean variable that
will retain the state indicating that the driver needs to
reattempt login with backing device firmware.
Signed-off-by: NThomas Falcon <tlfalcon@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

With this patch, User can configure for the supported
flows to be dropped. Added a stat "gft_filter_drop"
as well to be populated in ethtool for the dropped flows.

For example -

ethtool -N p5p1 flow-type udp4 dst-port 8000 action -1
ethtool -N p5p1 flow-type tcp4 scr-ip 192.168.8.1 action -1
Signed-off-by: NManish Chopra <manish.chopra@cavium.com>
Signed-off-by: NShahed Shaikh <shahed.shaikh@cavium.com>
Signed-off-by: NAriel Elior <ariel.elior@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

With the supported classification modes [4 tuples based,
udp port based, src-ip based], flows can be classified
to the VFs as well. With this patch, flows can be re-directed
to the requested VF provided in "action" field of command.

Please note that driver doesn't really care about the queue bits
in "action" field for the VFs. Since queue will be still chosen
by FW using RSS hash. [I.e., the classification would be done
according to vport-only]

For examples -

ethtool -N p5p1 flow-type udp4 dst-port 8000 action 0x100000000
ethtool -N p5p1 flow-type tcp4 src-ip 192.16.6.10 action 0x200000000
ethtool -U p5p1 flow-type tcp4 src-ip 192.168.40.100 dst-ip \
	192.168.40.200 src-port 6660 dst-port 5550 \
	action 0x100000000
Signed-off-by: NManish Chopra <manish.chopra@cavium.com>
Signed-off-by: NShahed Shaikh <shahed.shaikh@cavium.com>
Signed-off-by: NAriel Elior <ariel.elior@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently, driver supports flow classification to PF
receive queues based on TCP/UDP 4 tuples [src_ip, dst_ip,
src_port, dst_port] only.

This patch enables to configure different flow profiles
[For example - only UDP dest port or src_ip based] on the
adapter so that classification can be done according to
just those fields as well. Although, at a time just one
type of flow configuration is supported due to limited
number of flow profiles available on the device.

For example -

ethtool -N enp7s0f0 flow-type udp4 dst-port 45762 action 2
ethtool -N enp7s0f0 flow-type tcp4 src-ip 192.16.4.10 action 1
ethtool -N enp7s0f0 flow-type udp6 dst-port 45762 action 3
Signed-off-by: NManish Chopra <manish.chopra@cavium.com>
Signed-off-by: NShahed Shaikh <shahed.shaikh@cavium.com>
Signed-off-by: NAriel Elior <ariel.elior@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Validate and prevent some of the configurations for
unsupported [by firmware] inputs [for example - mac ext,
vlans, masks/prefix, tos/tclass] via ethtool -N/-U.
Signed-off-by: NManish Chopra <manish.chopra@cavium.com>
Signed-off-by: NShahed Shaikh <shahed.shaikh@cavium.com>
Signed-off-by: NAriel Elior <ariel.elior@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch simplifies the ethtool rx flow configuration
[via ethtool -U/-N] flow code base by dividing it logically
into various APIs based on given protocols. It also separates
various validations and calculations done along the flow
in their own APIs.
Signed-off-by: NManish Chopra <manish.chopra@cavium.com>
Signed-off-by: NShahed Shaikh <shahed.shaikh@cavium.com>
Signed-off-by: NAriel Elior <ariel.elior@cavium.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We have a confusion of two different abstractions in the Common
Code:  Physical Link (Port) and Logical Network Interface (Virtual
Interface), and we haven't been properly managing the state of the
intersection of those two abstractions.
On the one hand we have the Physical state of the Link -- up or down --
and on the other we have the logical state of the VI, enabled or not.
{ethN} refers to both the Physical and Logical State. In this case,
ifconfig only affects/interrogates the Logical State of a VI,
and ethtool only deals with the Physical State. And these are different.

So, just because we disable the VI, we don't really want to change the
Physical Link Up/Down state.  Thus, the previous hack to set
"lc->link_ok = 0" when we disable a VI is completely incorrect.

Where we get into trouble is where the Physical Link State and the
Logical VI State cross swords.  And that happens in
t4_handle_get_port_info() where we need to manage/safe the Physical
Link State, but we also need to know when the Logical VI State has
changed and pass that back up to the OS-dependent Driver routine
t4_os_link_changed() which is concerned about the Logical Interface.

So we enable a VI and that causes Firmware to send us a new Port
Information message, but if none of the Physical Link State
particulars have changed, we don't call t4_os_link_changed().

This fix uses the existing OS Contract APIs for the Common Code to
inform the OS-dependent portion of the Host Driver when the "Link" (really
Logical Network Interface) is "up" or "down". A new API
t4_enable_pi_params() is added which calls t4_enable_vi_params() and,
if that is successful, then calls back to the OS Contract API
t4_os_link_changed() notifying the OS-dependent layer of the
potential Link State change.

Original Work by : Casey Leedom <leedom@chelsio.com>
Signed-off-by: NSantosh Rastapur <santosh@chelsio.com>
Signed-off-by: NArjun Vynipadath <arjun@chelsio.com>
Signed-off-by: NGanesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

clean up init_one and use chip_ver consistently throughout
init_one() for chip version.
Signed-off-by: NCasey Leedom <leedom@chelsio.com>
Signed-off-by: NGanesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

newer SFPs like SFP28 and QSFP28 Transceiver Modules present
several new possibilities which we haven't faced before. Fix the
assumptions in the code reflecting the more limited capabilities
of previous Transceiver Module systems

Original work by Casey Leedom <leedom@chelsio.com>
Signed-off-by: NGanesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This comment is outdated as fec_ptp_ioctl has been replaced by fec_ptp_set/fec_ptp_get
since commit 1d5244d0 ("fec: Implement the SIOCGHWTSTAMP ioctl")
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Acked-by: NFugang Duan <fugang.duan@nxp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

efx_enqueue_skb() can push new buffers for the xmit_more functionality.
We must stops the TX queue before this or else the TX queue does not get
restarted and we get a netdev watchdog.

In the error handling we may now need to unwind more than 1 packet, and
we may need to push the new buffers onto the partner queue.

v2: In the error leg also push this queue if xmit_more is set

Fixes: e9117e50 ("sfc: Firmware-Assisted TSO version 2")
Reported-by: NJarod Wilson <jarod@redhat.com>
Tested-by: NJarod Wilson <jarod@redhat.com>
Signed-off-by: NMartin Habets <mhabets@solarflare.com>
Acked-by: NEdward Cree <ecree@solarflare.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When a system is under memory presure (high usage with fragments),
the original 256KB ICM chunk allocations will likely trigger kernel
memory management to enter slow path doing memory compact/migration
ops in order to complete high order memory allocations.

When that happens, user processes calling uverb APIs may get stuck
for more than 120s easily even though there are a lot of free pages
in smaller chunks available in the system.

Syslog:
...
Dec 10 09:04:51 slcc03db02 kernel: [397078.572732] INFO: task
oracle_205573_e:205573 blocked for more than 120 seconds.
...

With 4KB ICM chunk size on x86_64 arch, the above issue is fixed.

However in order to support smaller ICM chunk size, we need to fix
another issue in large size kcalloc allocations.

E.g.
Setting log_num_mtt=30 requires 1G mtt entries. With the 4KB ICM chunk
size, each ICM chunk can only hold 512 mtt entries (8 bytes for each mtt
entry). So we need a 16MB allocation for a table->icm pointer array to
hold 2M pointers which can easily cause kcalloc to fail.

The solution is to use kvzalloc to replace kcalloc which will fall back
to vmalloc automatically if kmalloc fails.
Signed-off-by: NQing Huang <qing.huang@oracle.com>
Acked-by: NDaniel Jurgens <danielj@mellanox.com>
Reviewed-by: NZhu Yanjun <yanjun.zhu@oracle.com>
Reviewed-by: NTariq Toukan <tariqt@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If the egress device of an offloaded rule is a LAG port, then encode the
output port to the NFP with a LAG identifier and the offloaded group ID.

A prelag action is also offloaded which must be the first action of the
series (although may appear after other pre-actions - e.g. tunnels). This
causes the FW to check that it has the necessary information to output to
the requested LAG port. If it does not, the packet is sent to the kernel
before any other actions are applied to it.
Signed-off-by: NJohn Hurley <john.hurley@netronome.com>
Reviewed-by: NPieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Reviewed-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Adds the control message handler to synchronize offloaded group config
with that of the kernel. Such messages are sent from fw to driver and
feature the following 3 flags:

- Data: an attached cmsg could not be processed - store for retransmission
- Xon: FW can accept new messages - retransmit any stored cmsgs
- Sync: full sync requested so retransmit all kernel LAG group info
Signed-off-by: NJohn Hurley <john.hurley@netronome.com>
Reviewed-by: NPieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Reviewed-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Monitor LAG events via the NETDEV_CHANGEUPPER/NETDEV_CHANGELOWERSTATE
notifiers to maintain a list of offloadable groups. Sync these groups with
HW via a delayed workqueue to prevent excessive re-configuration. When the
workqueue is triggered it may generate multiple control messages for
different groups. These messages are linked via a batch ID and flags to
indicate a new batch and the end of a batch.

Update private data in each repr to track their LAG lower state flags. The
state of a repr is used to determine the active netdevs that can be
offloaded. For example, in active-backup mode, we only offload the netdev
currently active.
Signed-off-by: NJohn Hurley <john.hurley@netronome.com>
Reviewed-by: NPieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Reviewed-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

LAG upper event notifiers contain the tx type used by the LAG device.
Extend this to also include the hash policy used for tx types that
utilize hashing.
Signed-off-by: NJohn Hurley <john.hurley@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a bitmap to each flower repr to track its state if it is enslaved by a
bond. This LAG state may be different to the port state - for example, the
port may be up but LAG state may be down due to the selection in an
active/backup bond.
Signed-off-by: NJohn Hurley <john.hurley@netronome.com>
Reviewed-by: NPieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Reviewed-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Check if the fw contains the _abi_flower_balance_sync_enable symbol. If it
does then write a 1 to this indicating that the driver is willing to
receive NIC to kernel LAG related control messages.

If the write is successful, update the list of extra features supported by
the fw and add a stub to accept LAG cmsgs.
Signed-off-by: NJohn Hurley <john.hurley@netronome.com>
Reviewed-by: NPieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Reviewed-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add an rtsym API function that combines the lookup of a symbol and the
writing of a value to it. Values can be written as unsigned 32 or 64 bits.
Signed-off-by: NJohn Hurley <john.hurley@netronome.com>
Reviewed-by: NPieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Reviewed-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Adding a netdev to a bond requires that its mac address can be modified.
The default eth_mac_addr is sufficient to satisfy this requirement.
Signed-off-by: NJohn Hurley <john.hurley@netronome.com>
Reviewed-by: NPieter Jansen van Vuuren <pieter.jansenvanvuuren@netronome.com>
Reviewed-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If the guest network adapter is not configured with DeviceNaming
enabled on the host, then the query for friendly name will return
success but with a zero length name. Which then leads to a garbage value
(stack contents) for ifalias.

Fix is simple, just don't set name if  host doesn't return it.

Fixes: 0fe554a4 ("hv_netvsc: propogate Hyper-V friendly name into interface alias")
Signed-off-by: NStephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In commit 624dbf55 ("driver/net: enic: Try DMA 64 first, then
failover to DMA") DMA mask was changed from 40 bits to 64 bits.
Hardware actually supports only 47 bits.

Fixes: 624dbf55 ("driver/net: enic: Try DMA 64 first, then failover to DMA")
Signed-off-by: NGovindarajulu Varadarajan <gvaradar@cisco.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The PPPIOCDETACH ioctl effectively tries to "close" the given ppp file
before f_count has reached 0, which is fundamentally a bad idea.  It
does check 'f_count < 2', which excludes concurrent operations on the
file since they would only be possible with a shared fd table, in which
case each fdget() would take a file reference.  However, it fails to
account for the fact that even with 'f_count == 1' the file can still be
linked into epoll instances.  As reported by syzbot, this can trivially
be used to cause a use-after-free.

Yet, the only known user of PPPIOCDETACH is pppd versions older than
ppp-2.4.2, which was released almost 15 years ago (November 2003).
Also, PPPIOCDETACH apparently stopped working reliably at around the
same time, when the f_count check was added to the kernel, e.g. see
https://lkml.org/lkml/2002/12/31/83.  Also, the current 'f_count < 2'
check makes PPPIOCDETACH only work in single-threaded applications; it
always fails if called from a multithreaded application.

All pppd versions released in the last 15 years just close() the file
descriptor instead.

Therefore, instead of hacking around this bug by exporting epoll
internals to modules, and probably missing other related bugs, just
remove the PPPIOCDETACH ioctl and see if anyone actually notices.  Leave
a stub in place that prints a one-time warning and returns EINVAL.

Reported-by: syzbot+16363c99d4134717c05b@syzkaller.appspotmail.com
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: NEric Biggers <ebiggers@google.com>
Acked-by: NPaul Mackerras <paulus@ozlabs.org>
Reviewed-by: NGuillaume Nault <g.nault@alphalink.fr>
Tested-by: NGuillaume Nault <g.nault@alphalink.fr>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>