The MANA driver causes a build failure in some configurations when
it selects an unavailable symbol:

WARNING: unmet direct dependencies detected for PCI_HYPERV
  Depends on [n]: PCI [=y] && X86_64 [=y] && HYPERV [=n] && PCI_MSI [=y] && PCI_MSI_IRQ_DOMAIN [=y] && SYSFS [=y]
  Selected by [y]:
  - MICROSOFT_MANA [=y] && NETDEVICES [=y] && ETHERNET [=y] && NET_VENDOR_MICROSOFT [=y] && PCI_MSI [=y] && X86_64 [=y]
drivers/pci/controller/pci-hyperv.c: In function 'hv_irq_unmask':
drivers/pci/controller/pci-hyperv.c:1217:9: error: implicit declaration of function 'hv_set_msi_entry_from_desc' [-Werror=implicit-function-declaration]
 1217 |         hv_set_msi_entry_from_desc(&params->int_entry.msi_entry, msi_desc);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~

A PCI driver should never depend on a particular host bridge
implementation in the first place, but if we have this dependency
it's better to express it as a 'depends on' rather than 'select'.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This causes error reported by kernel test robot.
Signed-off-by: Marek Behún <kabel@kernel.org>
Fixes: 41d26bf4 ("net: phy: marvell: refactor HWMON OOP style")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

When CONFIG_NET_SWITCHDEV is disabled, the shim for switchdev_port_attr_set
inside br_mc_disabled_update returns -EOPNOTSUPP. This is not caught,
and propagated to the caller of br_multicast_add_port, preventing ports
from joining the bridge.
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Fixes: ae1ea84b ("net: bridge: propagate error code and extack from br_mc_disabled_update")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The call to clk_disable_unprepare() can happen before priv is
initialized. This means moving clk_disable_unprepare out of
out_release into a new label.

Fixes: 8ef7adc6 ("net: ethernet: ravb: Enable optional refclk")
Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Sergei Shtylyov <sergei.shtylyov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

TSO and TBS cannot coexist, for now we set Intel mGbE controller to use
below TX Queue mapping: TxQ0 uses TSO and the rest of TXQs supports TBS.
Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Starting with patch:
a8b659e7 ("net: dsa: act as passthrough for bridge port flags")

drivers without "port_bridge_flags" callback will fail to join the bridge.
Looking at the code, -EOPNOTSUPP seems to be the proper return value,
which makes at least microchip and atheros switches work again.

Fixes: 5961d6a1 ("net: dsa: inherit the actual bridge port flags at join time")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

We recently added some new locking to this function but one error path
was overlooked.  We need to drop the lock before returning.

Fixes: f4da5652 ("net: stmmac: Add support for external trigger timestamping")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Wong Vee Khee <vee.khee.wong@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Tobias Waldekranz says:

====================
net: dsa: mv88e6xxx: Tiny fixes/improvements

Just some small things I have noticed that do not fit in any other
series.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Export the raw PVT data in a devlink region so that it can be
inspected from userspace and compared to the current bridge
configuration.
Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

In the unlikely event of the VTU being loaded to the brim with 4k
entries, the last one was placed in the buffer, but the size reported
to devlink was off-by-one. Make sure that the final entry is available
to the caller.

Fixes: ca4d632a ("net: dsa: mv88e6xxx: Export VTU as devlink region")
Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

Because ADRR is not a thing.
Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

Srujana Challa says:

====================
Add support for CN10K CPT block

OcteonTX3 (CN10K) silicon is a Marvell next-gen silicon. CN10K CPT
introduces new features like reassembly support and some feature
enhancements.
This patchset adds new mailbox messages and some minor changes to
existing mailbox messages to support CN10K CPT.

v1-v2
Fixed sparse warnings.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Adds a new mailbox to get CPT stats, includes performance
counters, CPT engines status and RXC status.
Signed-off-by: Narayana Prasad Raju Atherya <pathreya@marvell.com>
Signed-off-by: Srujana Challa <schalla@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

CN10K CPT coprocessor includes a component named RXC which
is responsible for reassembly of inner IP packets. RXC has
the feature to evict oldest entries based on age/threshold.
This patch adds a new mailbox to configure reassembly age
or threshold.
Signed-off-by: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
Signed-off-by: Srujana Challa <schalla@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Adds changes to existing CPT mailbox messages to support
CN10K CPT block. This patch also adds new register defines
for CN10K CPT.
Signed-off-by: Vidya Sagar Velumuri <vvelumuri@marvell.com>
Signed-off-by: Srujana Challa <schalla@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The mhi_wwan_rx_budget_dec function is supposed to return true if
RX buffer budget has been successfully decremented, allowing to queue
a new RX buffer for transfer. However the current implementation is
broken when RX budget is '1', in which case budget is decremented but
false is returned, preventing to requeue one buffer, and leading to
RX buffer starvation.

Fixes: fa588eba ("net: Add Qcom WWAN control driver")
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

The commit c329e5af ("net: phy: at803x: select correct page on
config init") selects the copper page during probe. This fails if the
copper page was already selected. In this case, the value of the copper
page (which is 1) is propagated through phy_restore_page() and is
finally returned for at803x_probe(). Fix it, by just using the
at803x_page_write() directly.

Also in case of an error, the regulator is not disabled and leads to a
WARN_ON() when the probe fails. This couldn't happen before, because
at803x_parse_dt() was the last call in at803x_probe(). It is hard to
see, that the parse_dt() actually enables the regulator. Thus move the
regulator_enable() to the probe function and undo it in case of an
error.

Fixes: c329e5af ("net: phy: at803x: select correct page on config init")
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: David Bauer <mail@david-bauer.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

The variable err is being initialized with a value that is
never read and it is being updated later with a new value.  The
initialization is redundant and can be removed

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

KASAN/syzbot had 4 reports, one of them being:

BUG: KASAN: slab-out-of-bounds in memcpy include/linux/fortify-string.h:191 [inline]
BUG: KASAN: slab-out-of-bounds in page_to_skb+0x5cf/0xb70 drivers/net/virtio_net.c:480
Read of size 12 at addr ffff888014a5f800 by task systemd-udevd/8445

CPU: 0 PID: 8445 Comm: systemd-udevd Not tainted 5.12.0-rc8-next-20210419-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:233
 __kasan_report mm/kasan/report.c:419 [inline]
 kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:436
 check_region_inline mm/kasan/generic.c:180 [inline]
 kasan_check_range+0x13d/0x180 mm/kasan/generic.c:186
 memcpy+0x20/0x60 mm/kasan/shadow.c:65
 memcpy include/linux/fortify-string.h:191 [inline]
 page_to_skb+0x5cf/0xb70 drivers/net/virtio_net.c:480
 receive_mergeable drivers/net/virtio_net.c:1009 [inline]
 receive_buf+0x2bc0/0x6250 drivers/net/virtio_net.c:1119
 virtnet_receive drivers/net/virtio_net.c:1411 [inline]
 virtnet_poll+0x568/0x10b0 drivers/net/virtio_net.c:1516
 __napi_poll+0xaf/0x440 net/core/dev.c:6962
 napi_poll net/core/dev.c:7029 [inline]
 net_rx_action+0x801/0xb40 net/core/dev.c:7116
 __do_softirq+0x29b/0x9fe kernel/softirq.c:559
 invoke_softirq kernel/softirq.c:433 [inline]
 __irq_exit_rcu+0x136/0x200 kernel/softirq.c:637
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:649
 common_interrupt+0xa4/0xd0 arch/x86/kernel/irq.c:240

Fixes: fb32856b ("virtio-net: page_to_skb() use build_skb when there's sufficient tailroom")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Reported-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: virtualization@lists.linux-foundation.org
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Fix phase offset calculation.
Signed-off-by: Radu Pirea (NXP OSS) <radu-nicolae.pirea@oss.nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Now that enetc supports flow control we have to make sure the settings in
the IERB are correct. Therefore, we actually depend on the enetc-ierb
module. Previously it was possible that this module was disabled while the
enetc was enabled. Fix it by automatically select the enetc-ierb module.

Fixes: e7d48e5f ("net: enetc: add a mini driver for the Integrated Endpoint Register Block")
Signed-off-by: Michael Walle <michael@walle.cc>
Acked-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

build_skb() is supposed to be followed by
skb_reserve(skb, NET_IP_ALIGN), so that IP headers are word-aligned.
(Best practice is to reserve NET_IP_ALIGN+NET_SKB_PAD, but the NET_SKB_PAD
part is only a performance optimization if tunnel encaps are added.)

Unfortunately virtio_net has not provisioned this reserve.
We can only use build_skb() for arches where NET_IP_ALIGN == 0

We might refine this later, with enough testing.

Fixes: fb32856b ("virtio-net: page_to_skb() use build_skb when there's sufficient tailroom")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: virtualization@lists.linux-foundation.org
Signed-off-by: David S. Miller <davem@davemloft.net>

bit operation helpers such as test_bit, clear_bit, etc take bit
position as parameter and not value. Current usage causes double
shift => BIT(BIT(0)). Fix that in wwan_core and mhi_wwan_ctrl.

Fixes: 9a44c1cc ("net: Add a WWAN subsystem")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Tobias Waldekranz says:

====================
net: dsa: Allow default tag protocol to be overridden from DT

This is a continuation of the work started in this patch:
https://lore.kernel.org/netdev/20210323102326.3677940-1-tobias@waldekranz.com/

In addition to the mv88e6xxx support to dynamically change the
protocol, it is now possible to override the protocol from the device
tree. This means that when a board vendor finds an incompatibility,
they can specify a working protocol in the DT, and users will not have
to worry about it.

Some background information:

In a system using an NXP T1023 SoC connected to a 6390X switch, we
noticed that TO_CPU frames where not reaching the CPU. This only
happened on hardware port 8. Looking at the DSA master interface
(dpaa-ethernet) we could see that an Rx error counter was bumped at
the same rate. The logs indicated a parser error.

It just so happens that a TO_CPU coming in on device 0, port 8, will
result in the first two bytes of the DSA tag being one of:

00 40
00 44
00 46

My guess was that since these values looked like 802.3 length fields,
the controller's parser would signal an error if the frame length did
not match what was in the header.

This was later confirmed using two different workarounds provided by
Vladimir. Unfortunately these either bypass or ignore the hardware
parser and thus robs working combinations of the ability to do RSS and
other nifty things. It was therefore decided to go with the option of
a DT override.

v1 -> v2:
  - Fail if the device does not support changing protocols instead of
    falling back to the default. (Andrew)
  - Only call change_tag_protocol on CPU ports. (Andrew/Vladimir)
  - Only allow changing the protocol on chips that have at least
    "undocumented" level of support for EDSA. (Andrew).
  - List the supported protocols in the binding documentation. I opted
    for only listing the protocols that I have tested. As more people
    test their drivers, they can add them. (Rob)

v2 -> v3:
  - Rename "dsa,tag-protocol" -> "dsa-tag-protocol". (Rob)
  - Some cleanups to 4/5. (Vladimir)
  - Add a comment detailing how tree/driver agreement on the tag
    protocol is enforced. (Vladimir).
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

The 'dsa-tag-protocol' is used to force a switch tree to use a
particular tag protocol, typically because the Ethernet controller
that it is connected to is not compatible with the default one.
Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Some combinations of tag protocols and Ethernet controllers are
incompatible, and it is hard for the driver to keep track of these.

Therefore, allow the device tree author (typically the board vendor)
to inform the driver of this fact by selecting an alternate protocol
that is known to work.
Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Previously DSA ports were also included, on the assumption that the
protocol used by the CPU port had to the matched throughout the entire
tree.

As there is not yet any consumer in need of this, drop the call.
Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

For devices that supports both regular and Ethertyped DSA tags, allow
the user to change the protocol.

Additionally, because there are ethernet controllers that do not
handle regular DSA tags in all cases, also allow the protocol to be
changed on devices with undocumented support for EDSA. But, in those
cases, make sure to log the fact that an undocumented feature has been
enabled.
Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

All devices are capable of using regular DSA tags. Support for
Ethertyped DSA tags sort into three categories:

1. No support. Older chips fall into this category.

2. Full support. Datasheet explicitly supports configuring the CPU
   port to receive FORWARDs with a DSA tag.

3. Undocumented support. Datasheet lists the configuration from
   category 2 as "reserved for future use", but does empirically
   behave like a category 2 device.

So, instead of listing the one true protocol that should be used by a
particular chip, specify the level of support for EDSA (support for
regular DSA is implicit on all chips). As before, we use EDSA for all
chips that fully supports it.

In upcoming changes, we will use this information to support
dynamically changing the tag protocol.
Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Merge tag 'mac80211-next-for-net-next-2021-04-20' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next

Johannes Berg says:

====================
Another set of updates, all over the map:
 * set sk_pacing_shift for 802.3->802.11 encap offload
 * some monitor support for 802.11->802.3 decap offload
 * HE (802.11ax) spec updates
 * userspace API for TDLS HE support
 * along with various other small features, cleanups and
   fixups
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

Petr Machata says:

====================
mlxsw: Refactor qdisc offload

Currently, mlxsw admits for offload a suitable root qdisc, and its
children. Thus up to two levels of hierarchy are offloaded. Often, this is
enough: one can configure TCs with RED and TCs with a shaper, and can even
see counters for each TC by looking at a qdisc at a sufficiently shallow
position.

While simple, the system has obvious shortcomings. It is not possible to
configure both RED and shaping on one TC. It is not possible to place a
PRIO below root TBF, which would then be offloaded as port shaper. FIFOs
are only offloaded at root or directly below, which is confusing to users,
because RED and TBF of course have their own FIFO.

This patchset is a step towards the end goal of allowing more comprehensive
qdisc tree offload and cleans up the qdisc offload code.

- Patches #1-#4 contain small cleanups.

- Up until now, since mlxsw offloaded only a very simple qdisc
  configurations, basically all bookkeeping was done using one container
  for the root qdisc, and 8 containers for its children. Patches #5, #6, #8
  and #9 gradually introduce a more dynamic structure, where parent-child
  relationships are tracked directly at qdiscs, instead of being implicit.

- This tree management assumes only one qdisc is created at a time. In FIFO
  handlers, this condition was enforced simply by asserting RTNL lock. But
  instead of furthering this RTNL dependence, patch #7 converts the whole
  qdisc offload logic to a per-port mutex.

- Patch #10 adds a selftest.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

There was a bug introduced during the rework which cause non-zero backlog
being stuck at ETS. Introduce a selftest that would have caught the issue
earlier.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mlxsw used to hold an array of qdiscs indexed by the TC number. In the
previous patch, it was changed to allocate child qdiscs dynamically, and
they are now indexed by band number. Follow suit with the array of future
FIFOs.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Instead of keeping qdiscs in globally-preallocated arrays, introduce a
per-qdisc-kind value num_classes, and then allocate the necessary child
qdiscs (if any) based on that value. Since now dynamic allocation is
involved, mlxsw_sp_qdisc_replace() gets messy enough that it is worth it to
split it to two cases: a new qdisc allocation and a change of existing
qdisc. (Note that the change also includes what TC formally calls replace,
if the qdisc kind is the same.)
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The FIFO handler currently guards accesses to the future FIFO tracking by
asserting RTNL. In the future, the changes to the qdisc state will be more
thorough, so other qdiscs will need this guarding is as well. In order
to not further the RTNL infestation, instead convert to a custom lock that
will guard accesses to the qdisc state.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

mlxsw currently allows a two-level structure of qdiscs: the root and
possibly a number of children. In order to support offloading more general
qdisc trees, introduce to struct mlxsw_sp_qdisc a pointer to child qdiscs.
Refer to the child qdiscs through this pointer, instead of going through
the tclass_qdiscs in qdisc_state. Additionally introduce a field
num_classes, which holds number of given qdisc's children.

Also introduce a generic function for walking qdisc trees. Rewrite
mlxsw_sp_qdisc_find() and _find_by_handle() to use the generic walker.

For now, keep the qdisc_state.tclass_qdisc, and just point root_qdiscs's
children to this array. Following patches will make the allocation dynamic.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

When a qdisc is removed, it is necessary to update the backlog value at its
parent--unless the qdisc is at root position. RED, TBF and FIFO all do
that, each separately. Since all of them need to do this, just promote the
operation directly to mlxsw_sp_qdisc_destroy(), instead of deferring it to
individual destructors. Since FIFO dtor thus becomes trivial, remove it.

Add struct mlxsw_sp_qdisc.parent to point at the parent qdisc. This will be
handy later as deeper structures are offloaded. Use the parent qdisc to
find the chain of parents whose backlog value needs to be updated.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tclass_num is just a number, a value that would be ordinarily passed around
as an int. (Which is unlike a u8 prio_bitmap.) In several places,
tclass_num already is an int. Convert the remaining instances.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The function mlxsw_sp_qdisc_compare() is invoked a couple lines above this
check, which will bounce any requests where this condition does not hold.
Therefore drop it.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The purpose of this function is to filter out events that are related to
qdiscs that are not offloaded, or are not offloaded anymore. But the
function is unnecessarily thorough:

- mlxsw_sp_qdisc pointer is never NULL in the context where it is called
- Two qdiscs with the same handle will never have different types. Even
  when replacing one qdisc with another in the same class, Linux will not
  permit handle reuse unless the qdisc type also matches.

Simplify the function by omitting these two unnecessary conditions.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>