calling dma_map_single()/dma_unmap_single() is quite expensive compared
to copying a small packet. So let's copy short frames and keep the buffers
mapped. We set the limit to 256 bytes which seems to give good results both
on the XP-GP board and on the AX3/4.

The Rx small packet rate increased by 16.4% doing this, from 486kpps to
573kpps. It is worth noting that even the call to the function
dma_sync_single_range_for_cpu() is expensive (300 ns) although less
than dma_unmap_single(). Without it, the packet rate raises to 711kpps
(+24% more). Thus on systems where coherency from device to CPU is
guaranteed by a snoop control unit, this patch should provide even more
gains, and probably rx_copybreak could be increased.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>
Tested-by: NArnaud Ebalard <arno@natisbad.org>
Signed-off-by: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Make use of build_skb() to allocate frags on the RX path. When frag size
is lower than a page size, we can use netdev_alloc_frag(), and we fall back
to kmalloc() for larger sizes. The frag size is stored into the mvneta_port
struct. The alloc/free functions check the frag size to decide what alloc/
free method to use. MTU changes are safe because the MTU change function
stops the device and clears the queues before applying the change.

With this patch, I observed a reproducible 2% performance improvement on
HTTP-based benchmarks, and 5% on small packet RX rate.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>
Tested-by: NArnaud Ebalard <arno@natisbad.org>
Signed-off-by: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently, the mvneta driver tries to prefetch the current Rx
descriptor during read. Tests have shown that prefetching the
next one instead increases general performance by about 1% on
HTTP traffic.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>
Tested-by: NArnaud Ebalard <arno@natisbad.org>
Signed-off-by: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

At several places, we already know the value of the rx status but
we call functions which dereference the pointer again to get it
and don't need the descriptor for anything else. Simplify this
task by replacing the rx desc pointer by the status word itself.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>
Tested-by: NArnaud Ebalard <arno@natisbad.org>
Signed-off-by: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Make mvneta_rxq_fill() use mvneta_rx_refill() instead of using
duplicate code.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>
Tested-by: NArnaud Ebalard <arno@natisbad.org>
Signed-off-by: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently, mvneta_txq_bufs_free() calls mvneta_tx_done_policy() with
a non-null cause to retrieve the pointer to the next queue to process.
There are useless tests on the return queue number and on the pointer,
all of which are well defined within a known limited set. This code
path is fast, although not critical. Removing 3 tests here that the
compiler could not optimize (verified) is always desirable.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>
Tested-by: NArnaud Ebalard <arno@natisbad.org>
Signed-off-by: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Right now the mvneta driver doesn't handle Tx IRQ, and relies on two
mechanisms to flush Tx descriptors : a flush at the end of mvneta_tx()
and a timer. If a burst of packets is emitted faster than the device
can send them, then the queue is stopped until next wake-up of the
timer 10ms later. This causes jerky output traffic with bursts and
pauses, making it difficult to reach line rate with very few streams.

A test on UDP traffic shows that it's not possible to go beyond 134
Mbps / 12 kpps of outgoing traffic with 1500-bytes IP packets. Routed
traffic tends to observe pauses as well if the traffic is bursty,
making it even burstier after the wake-up.

It seems that this feature was inherited from the original driver but
nothing there mentions any reason for not using the interrupt instead,
which the chip supports.

Thus, this patch enables Tx interrupts and removes the timer. It does
the two at once because it's not really possible to make the two
mechanisms coexist, so a split patch doesn't make sense.

First tests performed on a Mirabox (Armada 370) show that less CPU
seems to be used when sending traffic. One reason might be that we now
call the mvneta_tx_done_gbe() with a mask indicating which queues have
been done instead of looping over all of them.

The same UDP test above now happily reaches 987 Mbps / 87.7 kpps.
Single-stream TCP traffic can now more easily reach line rate. HTTP
transfers of 1 MB objects over a single connection went from 730 to
840 Mbps. It is even possible to go significantly higher (>900 Mbps)
by tweaking tcp_tso_win_divisor.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>
Cc: Arnaud Ebalard <arno@natisbad.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Tested-by: NArnaud Ebalard <arno@natisbad.org>
Signed-off-by: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Marvell has not published the chip's datasheet yet, so it's very hard
to find the relevant bits to manipulate to change the IRQ behaviour.
Fortunately, these bits are described in the proprietary LSP patch set
which is publicly available here :

    http://www.plugcomputer.org/downloads/mirabox/

So let's put them back in the driver in order to reduce the burden of
current and future maintenance.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>
Tested-by: NArnaud Ebalard <arno@natisbad.org>
Signed-off-by: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If a queue timeout is reported, we can oops because of some
schedules while the caller is atomic, as shown below :

  mvneta d0070000.ethernet eth0: tx timeout
  BUG: scheduling while atomic: bash/1528/0x00000100
  Modules linked in: slhttp_ethdiv(C) [last unloaded: slhttp_ethdiv]
  CPU: 2 PID: 1528 Comm: bash Tainted: G        WC   3.13.0-rc4-mvebu-nf #180
  [<c0011bd9>] (unwind_backtrace+0x1/0x98) from [<c000f1ab>] (show_stack+0xb/0xc)
  [<c000f1ab>] (show_stack+0xb/0xc) from [<c02ad323>] (dump_stack+0x4f/0x64)
  [<c02ad323>] (dump_stack+0x4f/0x64) from [<c02abe67>] (__schedule_bug+0x37/0x4c)
  [<c02abe67>] (__schedule_bug+0x37/0x4c) from [<c02ae261>] (__schedule+0x325/0x3ec)
  [<c02ae261>] (__schedule+0x325/0x3ec) from [<c02adb97>] (schedule_timeout+0xb7/0x118)
  [<c02adb97>] (schedule_timeout+0xb7/0x118) from [<c0020a67>] (msleep+0xf/0x14)
  [<c0020a67>] (msleep+0xf/0x14) from [<c01dcbe5>] (mvneta_stop_dev+0x21/0x194)
  [<c01dcbe5>] (mvneta_stop_dev+0x21/0x194) from [<c01dcfe9>] (mvneta_tx_timeout+0x19/0x24)
  [<c01dcfe9>] (mvneta_tx_timeout+0x19/0x24) from [<c024afc7>] (dev_watchdog+0x18b/0x1c4)
  [<c024afc7>] (dev_watchdog+0x18b/0x1c4) from [<c0020b53>] (call_timer_fn.isra.27+0x17/0x5c)
  [<c0020b53>] (call_timer_fn.isra.27+0x17/0x5c) from [<c0020cad>] (run_timer_softirq+0x115/0x170)
  [<c0020cad>] (run_timer_softirq+0x115/0x170) from [<c001ccb9>] (__do_softirq+0xbd/0x1a8)
  [<c001ccb9>] (__do_softirq+0xbd/0x1a8) from [<c001cfad>] (irq_exit+0x61/0x98)
  [<c001cfad>] (irq_exit+0x61/0x98) from [<c000d4bf>] (handle_IRQ+0x27/0x60)
  [<c000d4bf>] (handle_IRQ+0x27/0x60) from [<c000843b>] (armada_370_xp_handle_irq+0x33/0xc8)
  [<c000843b>] (armada_370_xp_handle_irq+0x33/0xc8) from [<c000fba9>] (__irq_usr+0x49/0x60)

Ben Hutchings attempted to propose a better fix consisting in using a
scheduled work for this, but while it fixed this panic, it caused other
random freezes and panics proving that the reset sequence in the driver
is unreliable and that additional fixes should be investigated.

When sending multiple streams over a link limited to 100 Mbps, Tx timeouts
happen from time to time, and the driver correctly recovers only when the
function is disabled.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Tested-by: NArnaud Ebalard <arno@natisbad.org>
Signed-off-by: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Stats writers are mvneta_rx() and mvneta_tx(). They don't lock anything
when they update the stats, and as a result, it randomly happens that
the stats freeze on SMP if two updates happen during stats retrieval.
This is very easily reproducible by starting two HTTP servers and binding
each of them to a different CPU, then consulting /proc/net/dev in loops
during transfers, the interface should immediately lock up. This issue
also randomly happens upon link state changes during transfers, because
the stats are collected in this situation, but it takes more attempts to
reproduce it.

The comments in netdevice.h suggest using per_cpu stats instead to get
rid of this issue.

This patch implements this. It merges both rx_stats and tx_stats into
a single "stats" member with a single syncp. Both mvneta_rx() and
mvneta_rx() now only update the a single CPU's counters.

In turn, mvneta_get_stats64() does the summing by iterating over all CPUs
to get their respective stats.

With this change, stats are still correct and no more lockup is encountered.

Note that this bug was present since the first import of the mvneta
driver.  It might make sense to backport it to some stable trees. If
so, it depends on "d33dc73 net: mvneta: increase the 64-bit rx/tx stats
out of the hot path".

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>
Reviewed-by: NEric Dumazet <edumazet@google.com>
Tested-by: NArnaud Ebalard <arno@natisbad.org>
Signed-off-by: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Better count packets and bytes in the stack and on 32 bit then
accumulate them at the end for once. This saves two memory writes
and two memory barriers per packet. The incoming packet rate was
increased by 4.7% on the Openblocks AX3 thanks to this.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>
Reviewed-by: NEric Dumazet <edumazet@google.com>
Tested-by: NArnaud Ebalard <arno@natisbad.org>
Signed-off-by: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

None of these files are actually using any __init type directives
and hence don't need to include <linux/init.h>.   Most are just a
left over from __devinit and __cpuinit removal, or simply due to
code getting copied from one driver to the next.

This covers everything under drivers/net except for wireless, which
has been submitted separately.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Pablo Neira Ayuso says:

====================
This small batch contains several Netfilter fixes for your net-next
tree, more specifically:

* Fix compilation warning in nft_ct in NF_CONNTRACK_MARK is not set,
  from Kristian Evensen.

* Add dependency to IPV6 for NF_TABLES_INET. This one has been reported
  by the several robots that are testing .config combinations, from Paul
  Gortmaker.

* Fix default base chain policy setting in nf_tables, from myself.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When ndo_neigh_setup is called, the bitfield used by NEIGH_VAR_SET is
not initialized yet. This might cause confusion for the people who use
NEIGH_VAR_SET in ndo_neigh_setup. So rather introduce NEIGH_VAR_INIT for
usage in ndo_neigh_setup.
Signed-off-by: NJiri Pirko <jiri@resnulli.us>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Aaron Brown says:

====================
Intel Wired LAN Driver Updates

This series contains several updates from Alex to ixgbe.

To avoid head of line blocking in the event a VF stops cleaning Rx descriptors
he makes sure QDE bits are set for a VF before the Rx queues are enabled.

To avoid a situation where the head write-back registers can remain set ofter
the driver is unloaded he clears them on a VF reset.

Alexander Duyck (2):
  ixgbe: Force QDE via PFQDE for VFs during reset
  ixgbe: Clear head write-back registers on VF reset
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The Tx head write-back registers are not cleared during an FLR or VF reset.
As a result a configuration that had head write-back enabled can leave the
registers set after the driver is unloaded.  If the next driver loaded doesn't
use the write-back registers this can lead to a bad configuration where
head write-back is enabled, but the driver didn't request it.

To avoid this situation the PF should be resetting the Tx head write-back
registers when the VF requests a reset.
Signed-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Tested-by: NPhil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: NAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This change makes it so that the QDE bits are set for a VF before the Rx
queues are enabled.  As such we avoid head of line blocking in the event
that the VF stops cleaning Rx descriptors for whatever reason.
Signed-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Tested-by: NPhil Schmitt <phillip.j.schmitt@intel.com>

 drivers/net/ethernet/intel/ixgbe/ixgbe_sriov.c |   14 ++++++++++++++
 drivers/net/ethernet/intel/ixgbe/ixgbe_type.h  |    7 ++++---
 2 files changed, 18 insertions(+), 3 deletions(-)
Signed-off-by: NAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Thomas Haller says:

====================
ipv6 addrconf: add IFA_F_NOPREFIXROUTE flag to suppress creation of IP6 routes

v1 -> v2: add a second commit, handling NOPREFIXROUTE in ip6_del_addr.
v2 -> v3: reword commit messages, code comments and some refactoring.
v3 -> v4: refactor, rename variables, add enum
v4 -> v5: rebase, so that patch applies cleanly to current net-next/master
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Refactor the deletion/update of prefix routes when removing an
address. Now also consider IFA_F_NOPREFIXROUTE and if there is an address
present with this flag, to not cleanup the route. Instead, assume
that userspace is taking care of this route.

Also perform the same cleanup, when userspace changes an existing address
to add NOPREFIXROUTE (to an address that didn't have this flag). This is
done because when the address was added, a prefix route was created for it.
Since the user now wants to handle this route by himself, we cleanup this
route.

This cleanup of the route is not totally robust. There is no guarantee,
that the route we are about to delete was really the one added by the
kernel. This behavior does not change by the patch, and in practice it
should work just fine.
Signed-off-by: NThomas Haller <thaller@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When adding/modifying an IPv6 address, the userspace application needs
a way to suppress adding a prefix route. This is for example relevant
together with IFA_F_MANAGERTEMPADDR, where userspace creates autoconf
generated addresses, but depending on on-link, no route for the
prefix should be added.
Signed-off-by: NThomas Haller <thaller@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This reverts commit 12afc36e.

The dependency is actually still necessary.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

add sctp_spp_sackdelay_{enable|disable} helper function for
avoiding code duplication.
Signed-off-by: NWang Weidong <wangweidong1@huawei.com>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Two places defined IPV6_TCLASS_SHIFT, so we should move it into ipv6.h,
and use this macro as possible. And define ip6_tclass helper to return
tclass
Signed-off-by: NLi RongQing <roy.qing.li@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Sathya Perla says:

====================
be2net: patch set

The following patch set is best suited for net-next as it
contains code-cleanup, support for newer versions of FW cmds and
a few minor fixes. Please apply. Thanks!
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NSathya Perla <sathya.perla@emulex.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch cleans-up wake-on-lan code in the following ways:
1) Removes some driver hacks in be_cmd_get_acpi_wol_cap() that were based
on incorrect assumptions.
2) Uses the adapter->wol_en and wol_cap variables for checking if WoL
is supported and enabled on an interface instead of referring to the
exclusion list via the macro be_is_wol_supported()
Signed-off-by: NSuresh Reddy <suresh.reddy@emulex.com>
Signed-off-by: NSathya Perla <sathya.perla@emulex.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The use of NTKW_MAC_QUERY cmd has been deprecated for Skyhawk-R.
Replace the last remaining usage in be_vfs_mac_query() routine.
Signed-off-by: NSuresh Reddy <suresh.reddy@emulex.com>
Signed-off-by: NSathya Perla <sathya.perla@emulex.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Instead, use the tail of the RXQ to pick the associated RXQ entry

This fix is required in preparation for supporting RXQ lengths greater than 1K.
For such queues, the frag index in the RX-compl entry is not valid as it is only a 10 bit entry not capable of addressing RXQs longer than 1K.
Signed-off-by: NSuresh Reddy <suresh.reddy@emulex.com>
Signed-off-by: NSathya Perla <sathya.perla@emulex.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As be2net is used even by the 40Gbps Skyhawk-R chip
Signed-off-by: NSuresh Reddy <suresh.reddy@emulex.com>
Signed-off-by: NSathya Perla <sathya.perla@emulex.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

An earlier commit (f25b119c "Fix error messages while driver load for VFs")
incorrectly set the adapter->cmd_privileges value for VFs (in a
multi-channel config) to MAX_PRIVILEGES. This causes FW cmd failures
and avoidable error logs when certian cmds are issued by a VF.
Also, move the multi-channel hack to be_cmds.c inside
be_cmd_get_fn_privileges() routine.

Fixes: f25b119c "Fix error messages while driver load for VFs"
Signed-off-by: NSuresh Reddy <suresh.reddy@emulex.com>
Signed-off-by: NSathya Perla <sathya.perla@emulex.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

An ndo_set_mac_addr() call may be issued for a mac-addr that is already
active on an interface. If so, silently ignore the request. Sending such
a request to the FW, causes a "mac collision" error. The error is harmless
but is avoidable noise in the kernel log.
Signed-off-by: NVasundhara Volam <vasundhara.volam@emulex.com>
Signed-off-by: NSathya Perla <sathya.perla@emulex.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Skyhawk-R FW does not support SET/GET_EXT_FAT_CAPABILITIES cmds via which
FW logging level can be controlled. Also, the hack used in BE3 to control
FW logging level via the ethtool interface is not needed in Skyhawk-R.

This patch also cleans up this code by moving be_set/get_fw_log_level()
routines to be_cmds.c where they belong.
Signed-off-by: NVasundhara Volam <vasundhara.volam@emulex.com>

remove new line
Signed-off-by: NSathya Perla <sathya.perla@emulex.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NVasundhara Volam <vasundhara.volam@emulex.com>
Signed-off-by: NSathya Perla <sathya.perla@emulex.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In the GET_HSW_CONFIG cmd, the "pport" field must be set only while
querying the switch mode.  When the "pport" field is set, the
"interface_id" field must be set to the port number, otherwise, it
must be set to adapter->if_handle.
Signed-off-by: NVasundhara Volam <vasundhara.volam@emulex.com>
Signed-off-by: NSathya Perla <sathya.perla@emulex.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently this cmd is used only for Lancer.
MCC_CREATE_EXT_V1 supports larger CQ-ids and additional event codes for the
async_event_bitmap field.
Signed-off-by: NVasundhara Volam <vasundhara.volam@emulex.com>
Signed-off-by: NSathya Perla <sathya.perla@emulex.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Some systems can use the normally known u16 alignment of
Ethernet addresses to save some code/text bytes and cycles.

This does not change currently emitted code on x86 by gcc 4.8.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

IEEE 802.15.4 and Bluetooth networking stacks share 6lowpan compression
code. Instead of introducing Makefile/Kconfig hacks, build this code as
a separate module referenced from both ieee802154 and bluetooth modules.

This fixes the following build error observed in some kernel
configurations:

net/built-in.o: In function `header_create': 6lowpan.c:(.text+0x166149): undefined reference to `lowpan_header_compress'
net/built-in.o: In function `bt_6lowpan_recv': (.text+0x166b3c): undefined reference to `lowpan_process_data'
Reported-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NDmitry Eremin-Solenikov <dmitry_eremin@mentor.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Veaceslav Falico says:

====================
net: rename device's sysfs symlinks on name change

First patch only adds helper functions and cleans up the code a bit, second
one already does the renaming.

v1->v2:
Don't export the function, as it's used only in dev.c.
====================
Reported-by: NDing Tianhong <dingtianhong@huawei.com>
CC: Ding Tianhong <dingtianhong@huawei.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Eric Dumazet <edumazet@google.com>
CC: Nicolas Dichtel <nicolas.dichtel@6wind.com>
CC: Cong Wang <amwang@redhat.com>
CC: netdev@vger.kernel.org
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently, we don't rename the upper/lower_ifc symlinks in
/sys/class/net/*/ , which might result stale/duplicate links/names.

Fix this by adding netdev_adjacent_rename_links(dev, oldname) which renames
all the upper/lower interface's links to dev from the upper/lower_oldname
to the new name.

We don't need a rollback because only we control these symlinks and if we
fail to rename them - sysfs will anyway complain.
Reported-by: NDing Tianhong <dingtianhong@huawei.com>
CC: Ding Tianhong <dingtianhong@huawei.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Eric Dumazet <edumazet@google.com>
CC: Nicolas Dichtel <nicolas.dichtel@6wind.com>
CC: Cong Wang <amwang@redhat.com>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

They clean up the code a bit and can be used further.

CC: Ding Tianhong <dingtianhong@huawei.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Eric Dumazet <edumazet@google.com>
CC: Nicolas Dichtel <nicolas.dichtel@6wind.com>
CC: Cong Wang <amwang@redhat.com>
Signed-off-by: NVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>