Some boards do not have the RX_ER MII signal connected. Normally in such
situation, those pins would be grounded, but then again, some boards
left it electrically floating.

When sending traffic to those switch ports, one can see that the
N_SOFERR statistics counter is incrementing once per each packet. The
user manual states for this counter that it may count the number of
frames "that have the MII error input being asserted prior to or
up to the SOF delimiter byte". So the switch MAC is sampling an
electrically floating signal, and preventing proper traffic reception
because of that.

As a workaround, enable the internal weak pull-downs on the input pads
for the MII control signals. This way, a floating signal would be
internally tied to ground.

The logic levels of signals which _are_ externally driven should not be
bothered by this 40-50 KOhm internal resistor. So it is not an issue to
enable the internal pull-down unconditionally, irrespective of PHY
interface type (MII, RMII, RGMII, SGMII) and of board layout.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Heiner Kallweit says:

====================
r8169: series with improvements

Again a series with few improvements.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Add workaround for hw issues with TSO on RTL8168evl. This workaround is
based on information I got from Realtek, and *should* allow to safely
enable TSO on this chip version.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Simplify the code and avoid the overhead of calling vlan_get_protocol().
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

At that place in rtl_init_one() we can safely use rtl8169_set_features()
to configure the chip according to the default features.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

So far we set RX_VLAN_8125 unconditionally, even if
NETIF_F_HW_VLAN_CTAG_RX may not be set. Don't touch these bits,
and let only rtl8169_set_features() control them.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

NETIF_F_HIGHDMA is added to vlan_features by register_netdev(),
therefore we can omit this here.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Move setting the ocp_base to rtl_init_one(). Where supported the value
is always the same, and if not supported it doesn't hurt.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Each ENETC station interface (SI) has a VLAN filter list and a port
flag (PSIPVMR) by which it can be put in "VLAN promiscuous" mode, which
enables the reception of VLAN-tagged traffic even if it is not in the
VLAN filtering list.

Currently the handling of this setting works like this: the port starts
off as VLAN promiscuous, then it switches to enabling VLAN filtering as
soon as the first VLAN is installed in its filter via
.ndo_vlan_rx_add_vid. In practice that does not work out very well,
because more often than not, the first VLAN to be installed is out of
the control of the user: the 8021q module, if loaded, adds its rule for
802.1p (VID 0) traffic upon bringing the interface up.

What the user is currently seeing in ethtool is this:
ethtool -k eno2
rx-vlan-filter: on [fixed]

which doesn't match the intention of the code, but the practical reality
of having the 8021q module install its VID which has the side-effect of
turning on VLAN filtering in this driver. All in all, a slightly
confusing experience.

So instead of letting this driver switch the VLAN filtering state by
itself, just wire it up with the rx-vlan-filter feature from ethtool,
and let it be user-configurable just through that knob, except for one
case, see below.

In promiscuous mode, it is more intuitive that all traffic is received,
including VLAN tagged traffic. It appears that it is necessary to set
the flag in PSIPVMR for that to be the case, so VLAN promiscuous mode is
also temporarily enabled. On exit from promiscuous mode, the setting
made by ethtool is restored.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

By default, the VCAP IS2 will produce a single match for each frame, on
the most specific classification.

Example: a ping packet (ICMP over IPv4 over Ethernet) sent from an IP
address of 10.0.0.1 and a MAC address of 96:18:82:00:04:01 will match
this rule:

tc filter add dev swp0 ingress protocol ipv4 \
	flower skip_sw src_ip 10.0.0.1 action drop

but not this one:

tc filter add dev swp0 ingress \
	flower skip_sw src_mac 96:18:82:00:04:01 action drop

Currently the driver does not really warn the user in any way about
this, and the behavior is rather strange anyway.

The current patch is a workaround to force matches on MAC_ETYPE keys
(DMAC and SMAC) for all packets irrespective of higher layer protocol.
The setting is made at the port level.

Of course this breaks all other non-src_mac and non-dst_mac matches, so
rule exclusivity checks have been added to the driver, in order to never
have rules of both types on any ingress port.

The bits that discard higher-level protocol information are set only
once a MAC_ETYPE rule is added to a filter block, and only for the ports
that are bound to that filter block. Then all further non-MAC_ETYPE
rules added to that filter block should be denied by the ports bound to
it.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Jeff Kirsher says:

====================
1GbE Intel Wired LAN Driver Updates 2020-04-17

This series contains updates to e1000e and igc only.

Sasha adds partial generic segmentation offload (GSO partial) support to
the igc driver.  Also added support for translating taprio schedules
into i225 cycles in igc.  Did clean up of dead code or unused defines in
the igc driver.  Refactored the code to avoid forward declarations where
possible.  Enables the NETIF_F_HW_TC flag for igc by default.

Vinicius adds support for ETF offloading using the similar approach that
taprio offload used.

Kees Cook fixes a clang warning in the e1000e driver by moving the
declared variable either into the switch case that uses the variable or
lift them up into the main function body, to help the compiler.

Andre fixed some register overwriting when dumping registers via ethtool
for igc driver.  Also fixed support for ethtool Network Flow
Classification (NFC) queue redirection by adding the missing code needed
to enable the queue selection feature from Receive Address High (RAH)
register.  Cleans up code to remove the code bits designed to support
tc-flower filters, since this client part does not support it.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

BCM53125 has internal Gigabit PHYs which support interrupts as well as
statistics, make it possible to configure both of those features with a
PHY driver entry.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Displaying the virtual address at which the MDIO base register address
has been mapped is not useful and is not visible with pointer hashing in
place, replace the message with something indicating successful
registration instead.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

Make use of platform_get_irq_byname_optional() to avoid printing
messages on the kernel console that interrupts cannot be found.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This adds support for the Qualcomm Atheros AR8032 Fast Ethernet PHY.

It shares many similarities with the already supported AR8030 PHY but
additionally supports MII connection to the MAC.
Signed-off-by: David Bauer <mail@david-bauer.net>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

Merge branch 'for-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth-next

Johan Hedberg says:

====================
pull request: bluetooth-next 2020-04-17

Here's the first bluetooth-next pull request for the 5.8 kernel:

 - Added debugfs option to control MITM flag usage during pairing
 - Added new BT_MODE socket option
 - Added support for Qualcom QCA6390 device
 - Added support for Realtek RTL8761B device
 - Added support for mSBC audio codec over USB endpoints
 - Added framework for Microsoft HCI vendor extensions
 - Added new Read Security Information management command
 - Fixes/cleanup to link layer privacy related code
 - Various other smaller cleanups & fixes
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

This patch fixes a bug when the user adds the first MAC address filter
via ethtool NFC mechanism.

When the first MAC address filter is added, it overwrites the default
MAC address filter configured at RAL[0] and RAH[0]. As consequence,
frames addressed to the interface MAC address are not sent to host
anymore.

This patch fixes the bug by calling igc_set_default_mac_filter() during
adapter init so the position 0 of adapter->mac_table[] is assigned to
the default MAC address.
Signed-off-by: Andre Guedes <andre.guedes@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

IGC driver has no support for tc-flower filters so this patch removes
some leftover code, probably copied from IGB driver by mistake.
Signed-off-by: Andre Guedes <andre.guedes@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

The support for ethtool Network Flow Classification (NFC) queue
redirection based on destination MAC address is currently broken in IGC.
For instance, if we add the following rule, matching frames aren't
enqueued on the expected rx queue.

$ ethtool -N IFNAME flow-type ether dst 3c:fd:fe:9e:7f:71 queue 2

The issue here is due to the fact that igc_rar_set_index() is missing
code to enable the queue selection feature from Receive Address High
(RAH) register. This patch adds the missing code and fixes the issue.
Signed-off-by: Andre Guedes <andre.guedes@intel.com>
Acked-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

i225 device support copper mode only
PHY signal detect indication for copper fiber switch
not applicable to i225 part
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

This assignment of the feature NETIF_F_HW_TC
occurs prior to the initial setup of the local
hw_features variable.

This ensures that NETIF_F_HW_TC are marked
as user changeable, and also enables it by
default when the driver loads.
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

IGC_START_ITR has beed defined twice
This patch come to fix it
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

This patch fixes some register overwriting when dumping registers via
ethtool.

We have a total of 16 RAL registers, starting at offset 139. So RAH
offset should be 139 + 16 = 155, not 145. As result some RAL registers
are overwritten. Likewise, RAH registers are also overwritten by TDBAL,
TDBAH, TDLEN, and TDH registers.

To fix this bug while preserving the ABI, this patch re-writes RAL and
RAH registers at the end of 'regs_buff' and bumps regs->version. It also
removes some pointless comments in the middle of igc_set_regs().
Signed-off-by: Andre Guedes <andre.guedes@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Move igc_adapter and igc_ring structures up to avoid
forward declaration
It is not necessary to forward declare these structures
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

We support only copper mode
Not applicable for i225 parts
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Formally Destination bit should be kept reserved to
support legacy drivers and ignore on write/read
operation
Not applicable for i225 parts
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Variables declared in a switch statement before any case statements
cannot be automatically initialized with compiler instrumentation (as
they are not part of any execution flow). With GCC's proposed automatic
stack variable initialization feature, this triggers a warning (and they
don't get initialized). Clang's automatic stack variable initialization
(via CONFIG_INIT_STACK_ALL=y) doesn't throw a warning, but it also
doesn't initialize such variables[1]. Note that these warnings (or silent
skipping) happen before the dead-store elimination optimization phase,
so even when the automatic initializations are later elided in favor of
direct initializations, the warnings remain.

To avoid these problems, move such variables into the "case" where
they're used or lift them up into the main function body.

drivers/net/ethernet/intel/e1000/e1000_main.c: In function ‘e1000_xmit_frame’:
drivers/net/ethernet/intel/e1000/e1000_main.c:3143:18: warning: statement will never be executed [-Wswitch-unreachable]
 3143 |     unsigned int pull_size;
      |                  ^~~~~~~~~

[1] https://bugs.llvm.org/show_bug.cgi?id=44916Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

This adds support for ETF offloading for the i225 controller.

For i225, the LaunchTime feature is almost a subset of the Qbv
feature. The main change from the i210 is that the launchtime of each
packet is specified as an offset applied to the BASET register. BASET
is automatically incremented each cycle.

For i225, the approach chosen is to re-use most of the setup used for
taprio offloading. With a few changes:

 - The more or less obvious one is that when ETF is enabled, we should
 set add the expected launchtime to the (advanced) transmit
 descriptor;

 - The less obvious, is that when taprio offloading is not enabled, we
 add a dummy schedule (all queues are open all the time, with a cycle
 time of 1 second).
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Reviewed-by: Andre Guedes <andre.guedes@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Adds support for translating taprio schedules into i225 cycles. This
will allow schedules to run in the hardware, making the schedules
enforcement more precise and saving CPU time.

Right now, the only simple schedules are allowed, complex schedules are
rejected. "simple" in this context are schedules that each HW queue is
opened and closed only once in each cycle.

Changing schedules is still not supported as well.
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Reviewed-by: Andre Guedes <andre.guedes@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Partial generic segmentation offload is a hybrid between TSO and GSO.
What is effectively does is take advantage of certain traits of TCP and
tunnels so that instead of having to rewrite the packet headers for each
segment only in the inner-most transport header and possible the outer-most
network header need to be updated.
This allows devices that do not support tunnel offload or tunnels
offloads with checksum to still make use of segmentation.
Signed-off-by: Sasha Neftin <sasha.neftin@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Merge tag 'tag-chrome-platform-fixes-for-v5.7-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux

Pull chrome-platform fixes from Benson Leung:
 "Two small fixes for cros_ec_sensorhub_ring.c, addressing issues
  introduced in the cros_ec_sensorhub FIFO support commit"

* tag 'tag-chrome-platform-fixes-for-v5.7-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux:
  platform/chrome: cros_ec_sensorhub: Add missing '\n' in log messages
  platform/chrome: cros_ec_sensorhub: Off by one in cros_sensorhub_send_sample()

Pull networking fixes from David Miller:

 1) Disable RISCV BPF JIT builds when !MMU, from Björn Töpel.

 2) nf_tables leaves dangling pointer after free, fix from Eric Dumazet.

 3) Out of boundary write in __xsk_rcv_memcpy(), fix from Li RongQing.

 4) Adjust icmp6 message source address selection when routes have a
    preferred source address set, from Tim Stallard.

 5) Be sure to validate HSR protocol version when creating new links,
    from Taehee Yoo.

 6) CAP_NET_ADMIN should be sufficient to manage l2tp tunnels even in
    non-initial namespaces, from Michael Weiß.

 7) Missing release firmware call in mlx5, from Eran Ben Elisha.

 8) Fix variable type in macsec_changelink(), caught by KASAN. Fix from
    Taehee Yoo.

 9) Fix pause frame negotiation in marvell phy driver, from Clemens
    Gruber.

10) Record RX queue early enough in tun packet paths such that XDP
    programs will see the correct RX queue index, from Gilberto Bertin.

11) Fix double unlock in mptcp, from Florian Westphal.

12) Fix offset overflow in ARM bpf JIT, from Luke Nelson.

13) marvell10g needs to soft reset PHY when coming out of low power
    mode, from Russell King.

14) Fix MTU setting regression in stmmac for some chip types, from
    Florian Fainelli.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (101 commits)
  amd-xgbe: Use __napi_schedule() in BH context
  mISDN: make dmril and dmrim static
  net: stmmac: dwmac-sunxi: Provide TX and RX fifo sizes
  net: dsa: mt7530: fix tagged frames pass-through in VLAN-unaware mode
  tipc: fix incorrect increasing of link window
  Documentation: Fix tcp_challenge_ack_limit default value
  net: tulip: make early_486_chipsets static
  dt-bindings: net: ethernet-phy: add desciption for ethernet-phy-id1234.d400
  ipv6: remove redundant assignment to variable err
  net/rds: Use ERR_PTR for rds_message_alloc_sgs()
  net: mscc: ocelot: fix untagged packet drops when enslaving to vlan aware bridge
  selftests/bpf: Check for correct program attach/detach in xdp_attach test
  libbpf: Fix type of old_fd in bpf_xdp_set_link_opts
  libbpf: Always specify expected_attach_type on program load if supported
  xsk: Add missing check on user supplied headroom size
  mac80211: fix channel switch trigger from unknown mesh peer
  mac80211: fix race in ieee80211_register_hw()
  net: marvell10g: soft-reset the PHY when coming out of low power
  net: marvell10g: report firmware version
  net/cxgb4: Check the return from t4_query_params properly
  ...

The driver uses __napi_schedule_irqoff() which is fine as long as it is
invoked with disabled interrupts by everybody. Since the commit
mentioned below the driver may invoke xgbe_isr_task() in tasklet/softirq
context. This may lead to list corruption if another driver uses
__napi_schedule_irqoff() in IRQ context.

Use __napi_schedule() which safe to use from IRQ and softirq context.

Fixes: 85b85c85 ("amd-xgbe: Re-issue interrupt if interrupt status not cleared")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Fix the following sparse warning:

drivers/isdn/hardware/mISDN/mISDNisar.c:746:12: warning: symbol 'dmril'
was not declared. Should it be static?
drivers/isdn/hardware/mISDN/mISDNisar.c:749:12: warning: symbol 'dmrim'
was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

After commit bfcb8132 ("net: dsa:
configure the MTU for switch ports") my Lamobo R1 platform which uses
an allwinner,sun7i-a20-gmac compatible Ethernet MAC started to fail
by rejecting a MTU of 1536. The reason for that is that the DMA
capabilities are not readable on this version of the IP, and there
is also no 'tx-fifo-depth' property being provided in Device Tree. The
property is documented as optional, and is not provided.

Chen-Yu indicated that the FIFO sizes are 4KB for TX and 16KB for RX, so
provide these values through platform data as an immediate fix until
various Device Tree sources get updated accordingly.

Fixes: eaf4fac4 ("net: stmmac: Do not accept invalid MTU values")
Suggested-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

In VLAN-unaware mode, the Egress Tag (EG_TAG) field in Port VLAN
Control register must be set to Consistent to let tagged frames pass
through as is, otherwise their tags will be stripped.

Fixes: 83163f7d ("net: dsa: mediatek: add VLAN support for MT7530")
Signed-off-by: DENG Qingfang <dqfext@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: René van Dorst <opensource@vdorst.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pull SELinux fix from Paul Moore:
 "One small SELinux fix to ensure we cleanup properly on an error
  condition"

* tag 'selinux-pr-20200416' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: free str on error in str_read()

Pull ceph fixes from Ilya Dryomov:

 - a set of patches for a deadlock on "rbd map" error path

 - a fix for invalid pointer dereference and uninitialized variable use
   on asynchronous create and unlink error paths.

* tag 'ceph-for-5.7-rc2' of git://github.com/ceph/ceph-client:
  ceph: fix potential bad pointer deref in async dirops cb's
  rbd: don't mess with a page vector in rbd_notify_op_lock()
  rbd: don't test rbd_dev->opts in rbd_dev_image_release()
  rbd: call rbd_dev_unprobe() after unwatching and flushing notifies
  rbd: avoid a deadlock on header_rwsem when flushing notifies

Pull tracing fix from Steven Rostedt:
 "This fixes a small race between allocating a snapshot buffer and
  setting the snapshot trigger.

  On a slow machine, the trigger can occur before the snapshot is
  allocated causing a warning to be displayed in the ring buffer, and no
  snapshot triggering. Reversing the allocation and the enabling of the
  trigger fixes the problem"

* tag 'trace-v5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix the race between registering 'snapshot' event trigger and triggering 'snapshot' operation

If seq_file .next function does not change position index,
read after some lseek can generate unexpected output:

    $ dd if=/proc/keys bs=1  # full usual output
    0f6bfdf5 I--Q---     2 perm 3f010000  1000  1000 user      4af2f79ab8848d0a: 740
    1fb91b32 I--Q---     3 perm 1f3f0000  1000 65534 keyring   _uid.1000: 2
    27589480 I--Q---     1 perm 0b0b0000     0     0 user      invocation_id: 16
    2f33ab67 I--Q---   152 perm 3f030000     0     0 keyring   _ses: 2
    33f1d8fa I--Q---     4 perm 3f030000  1000  1000 keyring   _ses: 1
    3d427fda I--Q---     2 perm 3f010000  1000  1000 user      69ec44aec7678e5a: 740
    3ead4096 I--Q---     1 perm 1f3f0000  1000 65534 keyring   _uid_ses.1000: 1
    521+0 records in
    521+0 records out
    521 bytes copied, 0,00123769 s, 421 kB/s

But a read after lseek in middle of last line results in the partial
last line and then a repeat of the final line:

    $ dd if=/proc/keys bs=500 skip=1
    dd: /proc/keys: cannot skip to specified offset
    g   _uid_ses.1000: 1
    3ead4096 I--Q---     1 perm 1f3f0000  1000 65534 keyring   _uid_ses.1000: 1
    0+1 records in
    0+1 records out
    97 bytes copied, 0,000135035 s, 718 kB/s

and a read after lseek beyond end of file results in the last line being
shown:

    $ dd if=/proc/keys bs=1000 skip=1   # read after lseek beyond end of file
    dd: /proc/keys: cannot skip to specified offset
    3ead4096 I--Q---     1 perm 1f3f0000  1000 65534 keyring   _uid_ses.1000: 1
    0+1 records in
    0+1 records out
    76 bytes copied, 0,000119981 s, 633 kB/s

See https://bugzilla.kernel.org/show_bug.cgi?id=206283

Fixes: 1f4aace6 ("fs/seq_file.c: simplify seq_file iteration code ...")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>